Java Programming.PDF

CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 1 of 68 thi Lab Guide for Java Programming CommunicationTeam.org CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 2 of 68 Contents THICOPYRIGHT NOTICE .................................................................................................. 1 COPYRIGHT NOTICE ............................................................. ERROR! BOOKMARK NOT DEFINED. DOCUMENT REVISION HISTORY ............................................... ERROR! BOOKMARK NOT DEFINED. CONTENTS .................................................................................................................. 2 1 CONTEXT ................................................................................................................. 4 2 ASSIGNMENTS FOR DAY 1 JAVA PROGRAMMING ............................................................. 4 ASSIGNMENT 1: OOAD OF TELE-COMMUNICATION COMPANY ............................................................... 4 ASSIGNMENT 2: USAGE OF ARRAY .......................................................................................... 5 ASSIGNMENT 3: MULTI-DIMENSIONAL ARRAYS ............................................................................... 7 ASSIGNMENT 4: CREATING A CLASS AND OBJECT ........................................................................... 9 ASSIGNMENT 5: PROBLEM DESCRIPTION TO JAVA PROGRAM .............................................................. 11 ASSIGNMENT 6: INITIALIZING THE CLASS MEMBER VARIABLES .............................................................. 11 ASSIGNMENT 7: ARCHITECTURAL NEUTRALITY OF JVM ................................................................... 12 ASSIGNMENT 8: UNDERSTANDING CLASSES ................................................................................ 13 ASSIGNMENT 9: METHOD OVERLOADING .................................................................................. 15 ASSIGNMENT 10: UNDERSTANDING CONSTRUCTORS ...................................................................... 18 ASSIGNMENT 10.A: UNDERSTANDING CONSTRUCTORS .................................................................... 18 ASSIGNMENT 10.B: UNDERSTANDING CONSTRUCTORS .................................................................... 20 ASSIGNMENT 10.C: UNDERSTANDING CONSTRUCTORS .................................................................... 22 ASSIGNMENT 10.D: UNDERSTANDING CONSTRUCTORS .................................................................... 23 ASSIGNMENT 11: ARRAYS OF OBJECTS ................................................................................... 25 3 ASSIGNMENTS FOR DAY 2 JAVA PROGRAMMING ........................................................... 27 ASSIGNMENT 12: STATIC CONCEPTS ...................................................................................... 27 ASSIGNMENT 12.A: STATIC CONCEPTS – STATIC VARIABLES ............................................................... 28 ASSIGNMENT 12.B: STATIC CONCEPTS -STATIC BLOCKS ................................................................. 29 ASSIGNMENT 12.C: STATIC CONCEPTS – PRIVATE CONSTRUCTORS AND STATIC METHODS .................................. 29 ASSIGNMENT 13: INHERITANCE ........................................................................................... 31 ASSIGNMENT 14: UNDERSTANDING INHERITANCE ......................................................................... 32 ASSIGNMENT 15: UNDERSTANDING DYNAMIC BINDING .................................................................... 36 ASSIGNMENT 16: UNDERSTANDING ABSTRACT CLASS ...................................................................... 38 ASSIGNMENT 17: UNDERSTANDING DYNAMIC BINDING .................................................................... 41 ASSIGNMENT 18: UNDERSTANDING INTERFACE ............................................................................ 43 ASSIGNMENT 19: UNDERSTANDING PACKAGES ............................................................................ 44 ASSIGNMENT 20: UNDERSTANDING THE ACCESS SPECIFIER ................................................................ 45 ASSIGNMENT 21: GARBAGE COLLECTION ................................................................................. 48 ASSIGNMENT 21A: GARBAGE COLLECTION ................................................................................ 49 ASSIGNMENT 21B: GARBAGE COLLECTION ................................................................................ 50 5 ASSIGNMENTS FOR DAY 3 JAVA PROGRAMMING ........................................................... 51 CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 3 of 68 ASSIGNMENT 22: AUTOBOXING AND UNBOXING ........................................................................... 51 ASSIGNMENT 23: UNDERSTANDING EXCEPTION HANDLING (UNCHECKED EXCEPTIONS) .................................... 52 ASSIGNMENT 24: UNDERSTANDING EXCEPTION HANDLING – TRY, CATCH & FINALLY ...................................... 55 ASSIGNMENT 25: UNDERSTANDING EXCEPTION HANDLING (CHECKED EXCEPTIONS) ....................................... 56 ASSIGNMENT 26: UNDERSTANDING USER DEFINED EXCEPTION HANDLING ................................................. 57 3 ASSIGNMENTS FOR DAY 4 JAVA PROGRAMMING ........................................................... 59 ASSIGNMENT 27: JAVABEANS ............................................................................................. 59 ASSIGNMENT 28: CREATING (JAVA BEAN) CLASSES AND OBJECT ......................................................... 60 ASSIGNMENT 29: USAGE OF „THIS‟ KEYWORD ............................................................................. 63 ASSIGNMENT 30: UNDERSTANDING COLLECTION FRAMEWORK ............................................................ 65 ASSIGNMENT 31: REFLECTION API ....................................................................................... 65 ASSIGNMENT 32: ANNOTATIONS .......................................................................................... 67 CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 4 of 68 1 Context This document contains assignments to be completed as part of the hands on for the subject Java programming  In order to complete the course, assignments in this document must be completed in the sequence mentioned.  Create a workspace on your desktop with the name “Java” for the assignments.  Under the “Java” folder,create project with names depending upon the day of assignment. If it is day 1 , create a project with the name “day1” in the “Java” workspace. Now for every assignment create a separate package. If some assignment requires multiple packages ( as in case of package assignments ) then create the nested packages. For example , assume your assignment is “assignment1” and you need to create two packages in this assignment ( “pack1” and “pack2” ) then you will be creating two packages with names “pack1” and “pack2” under package “assignment1”. 2 Assignments for Day 1 Java Programming Assignment 1: OOAD of Tele-Communication Company A telecom company wants to automate their process of giving mobile and internet connections and bill generation. The company has a set of customers. Each customer has a unique Customer ID, name and address. Telecom company offers two types of plans for their customers: a) Mobile Plans b) Internet Plans Mobile Plans can be of two types: Pre-paid or Post-paid. Internet Plans can also be of two types: Business Plan and Home Plan. A customer can have multiple plans. When the customer opts for a plan, he will be given a unique user-id and password for the specific plan. Bill should be generated at the end of every month for every customer. Identify the classes for the above problem. Solution: CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 5 of 68 Assignment 2: Usage of array Objective: To understand the usage of array. Problem Description: To calculate the feedback of 5 employees and grade them according to their feedback. Estimated time: 20 Mins. Step 1: Create a package for the assignment. Step 2: Open a Eclipse ganymede IDE and create a java file with the name EmployeeGrade : Filename EmployeeGrade.java CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 6 of 68 /* * This java file is a program to calculate the average feedback * of 5 employees and determine their grade *//** * This class will display the grade of 5 employees according * to their feedback. * Date : <> * @author <> * @version 1.0 */public class EmployeeGrade { /** * Calculates the average feedback of 5 employees and determines * their grade * @param args: Command line arguments */public static void main (String [] args) { //To-do: Calculate the average feedback of all the employees //To-do: Determine the grade of all the employees } } Save the file as „EmployeeGrade.java‟. Follow the below mentioned steps to complete the program Step 3: Inside the main method, declare 4 arrays for storing the employee numbers, customer1Feedback, customer2Feedback and customer3Feedback of 5 employees. Initialize them to any value. For e.g. int employeeId[]={1001,1002,1003,1004,1005}; float customer1Feedback[]={4.1f, 3.8f, 4.5f, 4.9f, 3.9f}; Assume employeeId[0] i.e. 1001 has customer 1 feedback as customer1Feedback[0] i.e. 4.1 and so on Step 4: Declare a float array averageFeedback [] to store the average feedback of all the employees. Step 5: Declare a char array grade [] to store the grade of all the employees. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 7 of 68 Step 6: Calculate the average feedback and determine the grade . Store the average feedback of all the employees in averageFeedback [] array and the grades in grade[] array. Use looping control statements to access the values from the arrays. Step 7: Display the employee number, average feedback and grade of all the employees. Step 8: Compile EmployeeGrade.java. Resolve the errors if any, and recompile the program. Step 9: Execute EmployeeGrade.java. Summary of this exercise: You have just learnt  To declare, initialize and access arrays.  To use looping control statements. Assignment 3: Multi-dimensional Arrays Objective: To understand the two-dimensional arrays. Problem Description: Create a class EmployeeFeedback that stores the employee number and the feedback from their customers. Note: Not necessarily, all the employees would have the same number of customers. Estimated time: 15 Mins. Step 1: Create a package for the assignment. Step 2: Open Eclipse ganymede IDE and type the following: Filename EmployeeFeedback.java /* * This java file is a program to store and display the employee * number and their feedback from the customer. *//** * This class will display the feedback of all the employees * Date : <> * @author <> CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 8 of 68 * @version 1.0 */public class EmployeeFeedback { /** * Stores and displays the feedback of the employees from their * customer * @param args: Command line arguments */public static void main (String [] args) { int [][]empInfo = {{1001,4,5}, {1002,2,4,5}}; for (int outerLoop=0;outerLoop<2;outerLoop++) { for (int innerLoop=0;innerLoop<3;innerLoop++) { System.out.println(empInfo[outerLoop][innerLoop]); } } } } Save the file as „EmployeeFeedback.java‟ Step 3: Compile and execute the code. Now, 1001 has feedback from 2 customers and 1002 has feedback from 3 customers. Do you get to display all the values? You would get run-time exception, if you try to change the upper limit of the array from 3 to 4. (Analyze and find out the reason). Now, instead of mentioning the constant as upper limit for the array, use the length property. for (int outerLoop=0;outerLoop> * @author <> * @version 1.0 */public class Customer { private String customerID; private String customerName; private String address; private int pinCode; /** * This method creates an object of Customer Class and sets its *instance variable and display the same. * @param args The command line arguments */public static void main (String [] args){ Customer customer = new Customer(); //statement 1 customer.customerID = “1234”; //statement 2 customer.customerName = “Jayant”; //statement 3 CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 10 of 68 customer.address = “PHA-Sawan Apts., Yadavgiri, Hyderabad”; //statement 4 customer.pinCode = 570020; //statement 5 System.out.println(“Customer ID ” + customer.customerID); System.out.println(“Customer Name ” + customer.customerName); System.out.println(“Customer Address ” + customer.address); System.out.println(“Customer Pin Code ” + customer.pinCode); } } Save the file as : Sample.java Step 2: Compile the program. Read the error reported and fix it (refer to the Note given below). 1. In a java file, if the class is declared as public, the name of the class and the name of the file should be the same (including the case). 2. The main() method is the starting point of the program. It is not mandatory for all the classes to have the main() method. The class with main() method is called „Starter class‟. Step 3: Execute the program. Step 4: In the above code main method is a part of Customer class. Step 5: Try to understand the program. Statement 1: Creates an instance of type Customer and the instance is assigned to the reference variable “customer”. (More about this on Day 2) Statement 2…5: Using the reference variable assigning value to the member variable of the class (similar to structure concept in C) The following statements retrieve the values assigned to the member variables and display it. This exercise is just for demo purpose. The program does not adhere to the OO concepts. Summary of this exercise: CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 11 of 68 You have just learnt  Creating object of a class  How to access instance variables of an object Assignment 5: Problem Description to Java Program CityBank is a multinational private bank. CommunicationTeam employees can open a bank account in CityBank on the day of their joining. Account can be of two types (1) Salary Account and (2) Non Salary Account. For non salary account the minimum bank balance should be Rs 10,000/-. There are different privilege levels (shown in the table below) available on both the accounts. Type of customer Privileges Salary Non-salary Multi city cheque book No No Discount on shopping using debit card No Yes ATM card Yes Yes The application is used by the clerk of the bank. On allocating it should return a customer id and Account Number. To open a bank account following details are required by the bank: 1 Applicant first, middle and last name 2. Email-id 3. Account Type 4. Date of Birth 5. Gender (M/F) 6. Marital status (Single /Married) Write a program in Java to represent the above description. Assignment 6: Initializing the class member variables Modify the above program to get the new account number for the following new employees of CommunicationTeam: CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 12 of 68 Employee 1: Employee 2: Name First: Paul Middle: J Last: Anderson First: John Middle: Last: Jacob Date of Birth 3rd Jan,1985 6th March, 1985 Email-id Paul@CommunicationTeam.com John@CommunicationTeam.com Account Type Salary Non-Salary Gender M M Marital Status Single Married Hint: A constructor can be used to initialize class member variables. Assignment 7: Architectural neutrality of JVM CityBank software is made to be deployed on different architectures. Fill out the below diagram to complete depict the flow of deploying InyBank software which is written in Java. A .class files .java files B1 B2 B3 Q1. What is done in Step A to get .class files? Q2. .class files are also known as __________? Are the .class files platform independent (Yes/No)? Q3. Which software is used at B1, B2, B3 to deploy CityBank software? Is the software platform independent (Yes/No)? Apple Machine Windows Machine Unix Machine CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 13 of 68 Assignment 8: Understanding Classes Problem Description: Create a class to store the employee information and calculate the average feedback and grade based on their feedback. Create the starter class to instantiate the employee and invoke the methods. Estimated time: 15 Mins. Step 1: Create the class EmployeeGrade according to the below given class diagram. EmployeeGrade -employeeNo : int -employeeName : String -customer1Feedback: float -customer2Feedback: float -customer3Feedback: float -averageFeedback : float -grade : char + initializeEmployee(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback, float customer3Feedback) : void + calculateAverageFeedback() : void + calculateGrade() : void + displayInfo() : void initializeEmployee(..) : This method initialize employee No, name, feedback from 3 customers to the member variables. Remember to use „this‟. calculateAverageFeedback() : This method calculates the average of the 3 feedback and store it in the corresponding member variable. calculateGrade() : This method calculates the grade for the employee based on his average feedback. displayInfo(): This method displays the employeeNo, name, average feedback and the grade of the employee. Step 2: Save the class under the package of the assignment and compile the program. Fix the errors, if any. Step 3: create a starter class with the name City as given below. Filename City.java /* * This java file is a starter class which instantiates EmployeeGrade CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 14 of 68 * Calls the corresponding methods to initialize the values * Calculate the average feedback and the grade * Display the information *//** * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average feedback * and grade. Invoke the method to display the employee information. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create an instance (Elvis) for EmployeeGrade class. //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information } } Save the file as : City.java. Step 4: Compile City.java. Fix the errors, if any. Step 5: Execute City.java. Check the output. The program displays the default value for all the member variables. The reason being, the main() of the starter class has not invoked the method that initializes the member variables. The default constructor for EmployeeGrade has not been defined. Hence the compiler adds the „default constructor‟ and initializes the variables to the default value, based on their data type. Step 6: Modify the main() in City.java to invoke the method that initializes the member variables, before invoking the method that calculates the average feedback and grade. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 15 of 68 Step 7: Compile City.java and execute the program. It should display the information about the employee. Summary of this exercise: You have learnt  Initializing the member variables using user-defined methods.  If the constructor is not defined in the program, the system automatically provides the default constructor and initializes the member variables with default values based on the data type.  If the member variables are not initialized through the constructor, the programmer should invoke the method that initializes the member variables, if defined. Assignment 9: Method Overloading Problem Description: Create a class to store the employee information and calculate the average feedback and grade based on their feedback. Create the starter class to instantiate the employee and invoke the methods. Estimated time: 15 Mins. Step 1: Create the class EmployeeGrade according to the below given class diagram. EmployeeGrade -employeeNo : int -employeeName : String -customer1Feedback: float -customer2Feedback: float -customer3Feedback: float -averageFeedback : float -grade : char + initializeEmployee(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback, float customer3Feedback) : void + initializeEmployee(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback) : void + calculateAverageFeedback() : void + calculateGrade() : void + displayInfo() : void CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 16 of 68 initializeEmployee(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback, float customer3Feedback) This method initialize employee No, name, feedback from 3 customers to the member variables. Remember to use „this‟. initializeEmployee(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback) This method initialize employee No, name, feedback from 2 customers to the member variables. Remember to use „this‟. calculateAverageFeedback() : This method calculates the average of the available feedback and store it in the corresponding member variable calculateGrade() : This method calculates the grade for the employee based on his average feedback. displayInfo(): This method displays the employeeNo, name, average feedback and the grade of the employee. Step 2: Save the class under the package of this assignment and compile the program. Fix the errors, if any. Step 3: create a starter class with the name City as given below, under the package. Filename City.java /* * This java file is a starter class which instantiates EmployeeGrade * Calls the corresponding methods to initialize the values * Calculate the average feedback and the grade * Display the information *//** * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average feedback * and grade. Invoke the method to display the employee information. * @param args The command line arguments */CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 17 of 68 public static void main (String[] args) { //To-do: Create an instance (Elvis) for EmployeeGrade class. //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information //To-do: Create an instance (Martha) for EmployeeGrade class. //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information } } Save the file as : City.java. Step 4: Compile City.java. Fix the errors, if any. Step 5: Execute City.java. Check the output. Now, open the City.java and modify the program to invoke the method that initializes the member variables, before invoking the method to calculate the average feedback and grade, as given in step 6. Step 6: Call the initializeEmployee method for Elvis as well Martha. All the 3 customers have given the feedback for Elvis as 4.1, 3,9 and 4.2. But only 2 customers have given the feedback for Martha as 4.2 and 4.4. Alter the main() method of City.java program as follows. public static void main (String[] args) { //To-do: Create an instance (Elvis) for EmployeeGrade class //To-do: Call the initializeEmployee with 3 feedback //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information //To-do: Create an instance (Elvis) for EmployeeGrade class //To-do: Call the initializeEmployee with 2 feedback //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information } Step 7: Compile City.java and execute the program. It should display the information about the employee. Summary of this exercise: CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 18 of 68 You have learnt  Initializing the member variables using user-defined methods.  If the constructor is not defined in the program, the system automatically provides the default constructor and initializes the member variables with default values based on the data type.  If the member variables are not initialized through the constructor, the programmer should invoke the method that initializes the member variables, if defined.  The methods can be overloaded. If overloaded, the compiler decides the method to be executed based on the method signature. Assignment 10: Understanding Constructors Objective: To understand the usage and the implementation of constructors. Assignment 10.a: Understanding Constructors Problem Description: Create a class to store the employee information and calculate the average feedback and grade based on their feedback. Use the constructor to initialize the member variables. Create the starter class to instantiate the employee and invoke the methods. Estimated time: 15 Mins. Step 1: Create the class EmployeeGrade under the package based on the below given class diagram. EmployeeGrade -employeeNo : int -employeeName : String -customer1Feedback: float -customer2Feedback: float -customer3Feedback: float -averageFeedback : float -grade : char + EmployeeGrade() + calculateAverageFeedback() : void + calculateGrade() : void + displayInfo() : void CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 19 of 68 EmployeeGrade() : This is the default constructor which initializes the member variables with values as follows. Employee No :101, Name: “Ram”, customer1Feedback: 4.1f, customer2Feedback: 4.0f, customer3Feedback: 4.3f Step 2: Compile EmployeeGrade and fix the errors, if any. Step 3: Create a starter class with the name City as given below. Filename City.java /* * This java file is a starter class which instantiates EmployeeGrade. * Calculate the average feedback and the grade * Display the information *//** * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average * feedback and grade. Invoke the method to display the employee * information. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create instance(ram) for EmployeeGrade. //To-do: Invoke methods for calculating Avg feedback & grade //To-do: Invoke method to display the employee information } } Save the file as : City.java. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 20 of 68 Step 4: Compile City.java. Fix the errors, if any. Step 5: Execute City.java. Check the output. It should display the information about employee 101. If the default constructor is defined for initializing the values, you need not explicitly invoke any method to initialize the values. But when the default constructor is used to initialize the values like shown in the exercise, every instance is initialized with same values! Summary of this exercise: You have learnt  Initializing the member variables within default constructor.  If initialized within constructor, need not explicitly invoke any method to initialize.  The same values are initialized to all the instances. Assignment 10.b: Understanding Constructors Problem Description: Create a class to store the employee information and calculate the average feedback and grade based on their feedback. Use the constructor to initialize the member variables. Create the starter class to instantiate the employee and invoke the methods. Estimated time: 15 Mins. Step 1: Make a copy of EmployeeGrade of Assignment 10.a, under the package of this assignment. Modify the EmployeeGrade according to the below given class diagram. EmployeeGrade -employeeNo : int -employeeName : String -customer1Feedback: float -customer2Feedback: float -customer3Feedback: float -averageFeedback : float -grade : char + EmployeeGrade() + EmployeeGrade(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback, float customer3Feedback) + calculateAverageFeedback() : void + calculateGrade() : void + displayInfo() : void CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 21 of 68 EmployeeGrade() : This is the default constructor which initializes the member variables to their default values, based on the data type of the variable. EmployeeGrade(int employeeNo, String employeeName, float customer1Feedback, float customer2Feedback, float customer3Feedback) : This is the overloaded constructor, which initializes the member variables with the values being passed as parameter. Step 2: Compile EmployeeGrade and fix the errors, if any. Step 3: Create a starter class with the name City as given below. Filename City.java /* * This java file is a starter class which instantiates EmployeeGrade. * Calculate the average feedback and the grade * Display the information *//** * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average * feedback and grade. Invoke the method to display the employee * information. * @param args The command line arguments */public static void main (String[] args) { EmployeeGrade ram = new EmployeeGrade(); EmployeeGrade james = new EmployeeGrade(102,”James”,4.2f,4.4f,4,1f); //To-do: Invoke methods for calculating Avg feedback & grade for both the employees CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 22 of 68 //To-do: Invoke method to display the employee information for both the employees } } Save the file as : City.java Step 4: Compile City.java. Fix the errors, if any. Step 5: Execute City.java. Analyze the output. Summary of this exercise: You have learnt  Initializing the member variables within default constructor.  Initializing the member variables using overloaded constructor. Assignment 10.c: Understanding Constructors Problem Description: Create a class to store the employee information and calculate the average feedback and the grade based on their feedback. Use the constructor to initialize the member variables. Creating the starter class to instantiate the EmployeeGrade and invoke the methods. -Estimated time: 15 Mins. Step 1: Make a copy of EmployeeGrade of Assignment 10.b, under the package of this assignment. Step 2: Modify the EmployeeGrade.java by commenting the default constructor of the EmployeeGrade class. Step 3: Save the program and compile it. Fix the errors, if any. Step 4: In City.java, comment the instance „ram‟ and all the statements that invoke the methods through the instance ram. /* * This java file is a starter class which instantiates EmployeeGrade. * Calculate the average feedback and the grade * Display the information *//** CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 23 of 68 * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average * feedback and grade. Invoke the method to display the employee * information. * @param args The command line arguments */public static void main (String[] args) { //EmployeeGrade ram = new EmployeeGrade(); EmployeeGrade james = new EmployeeGrade(102,”James”,4.2f,4.4f,4,1f); //To-do: Invoke methods for calculating Avg feedback & grade for „james‟ alone //To-do: Invoke method to display the employee information for „james‟ alone } } Save the program. Step 5: Compile the program. Fix the errors, if any Step 6: Execute the program. Summary of this exercise: You have learnt  Initializing the member variables using the overloaded constructor, without defining the default constructor. Assignment 10.d: Understanding Constructors CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 24 of 68 Problem Description: Create a class to store the employee information and calculate the average feedback and grade based on their feedback. Use the constructor to initialize the member variables. Creating the starter class to instantiate the employee and invoke the methods. Estimated time: 15 Mins. Step 1: Make a copy of EmployeeGrade.java and City.java of Assignment 10.c, under the package of this assignment. Step 2: Modify City.java by removing the comment for the statement that creates an instance for „ram‟, as given below. /* * This java file is a starter class which instantiates EmployeeGrade. * Calculate the average feedback and the grade * Display the information *//** * This class is a starter class that instantiates the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Displays the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Instantiate the EmployeeGrade. Set the values for the member * variables and invoke the method to calculate the average * feedback and grade. Invoke the method to display the employee * information. * @param args The command line arguments */public static void main (String[] args) { EmployeeGrade ram = new EmployeeGrade(); EmployeeGrade james = new EmployeeGrade(102,”James”,4.2f,4.4f,4,1f); //To-do: Invoke methods for calculating Avg feedback & grade for „James‟ alone CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 25 of 68 //To-do: Invoke method to display the employee information for „James‟ alone } } Save the program. Step 3: Compile the program. Look into the compilation error and understand the reason. The compiler would provide the default constructor, only if no other constructors are defined in the program. Here, the program has defined the overloaded constructor. So, the system doesn‟t generate the default constructor. When you try to call the default constructor, it would throw an error that there is no default constructor. Remove the comment for the default constructor in the class EmployeeGrade. Compile the code. Execute City.java Summary of this exercise: You have learnt  When the parameterized constructors are defined but not the default constructor, if you try to invoke the default constructor, you would get compilation error. Assignment 11: Arrays of Objects Objective: To understand how to create and use arrays of objects. Problem Description: Create a class that stores information about employees and calculates their grades according to the feedbacks. Use EmployeeGrade class created in Assignment 10.b. Estimated time: 15 Mins. When the grade is to be determined for just 2 or 3 employees, separate objects can be created. But what if there are more than 10 or 20 employees. It is not feasible to create separate objects. That‟s where array of objects is used. Step 1: Make a Copy of EmployeeGrade.java from Assignment 10.b under the package of this assignment. Step 2: Create City.java under the current package, which creates array of objects for EmployeeGrade, so that the employee grade can be calculated for any number of employees. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 26 of 68 Filename City.java /* * This java file is a starter class which instantiates EmployeeGrade. * Calculates and displays the average feedback and the grade *//** * This class is a starter classes that instantiate the EmployeeGrade. * Using the instance, the class should call the corresponding methods * to calculate the average feedback and grade. * Display the information. * Date : <> * @author <> * @version 1.0 */public class City { /** * Calculates the average feedback of employees and determines * the grade. * @param args: Command line arguments */public static void main (String [] args) { //create an array of 5 references of EmployeeGrade class EmployeeGrade [] employee = new EmployeeGrade[5]; //To-do: Initialize the references by calling the parameterized constructor. //To-do: Call the corresponding methods to calculate average feedback and grade for all the 5 employees. //To-do: Display the details for all the 5 employees } } Save the file as „City.java‟ Step 3: Compile the program. Fix the errors, if any CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 27 of 68 When an array of objects are created like below, EmployeeGrade [] employeeGrade=new EmployeeGrade[10]; they are references pointing to null. To create objects, the constructor should be called on every index of the array as given below, after declaring the array. for(int loop=0;loop> * @author <> * @version 1.0 */public class CityBank { /** * Instantiate the Account object. Call the corresponding methods that * does the various banking operations. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create an instance (john) for Customer class. Call the overloaded constructor SavingsAccount johnSA = new SavingsAccount(101,john,1000); johnSA.deposit(1000); //To-do: display the balance available in account no 101 //To-do: call the method to withdraw Rs.1600. //To-do: display the balance available. //To-do: Create an instance (jenny) for Customer class. Call the overloaded constructor OverdraftAccount jennyOA = new OverdraftAccount(201,jenny,500,2000); //To-do: deposit Rs. 1500 to the account //To-do: display the balance available in account no 201 Note: available balance for Overdraft Account is balance+ Allowed negative amount //To-do: call the method to withdraw Rs. 1000 //To-do: display the balance available //To-do: call the method to withdraw Rs. 4000 //To-do: display the balance available //To-do: call the method to withdraw Rs. 3000 //To-do: display the balance available } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 36 of 68 } Step 5: Save and compile all the programs. Fix errors, if any. Step 6: Execute CityBank. Analyze the outputs. Summary of this exercise: You have just learnt  To identify classes and their relationship (OO Analysis)  To identify data members and methods (OO Design)  To design the classes  To implement the classes Assignment 15: Understanding Dynamic Binding Objective: To understand dynamic binding, run-time polymorphism and its usages. Problem Description: Making the CityBank.java to implement the dynamic binding and run-time polymorphism. Estimated time: 20 Mins. Step 1: Make a copy of Customer, Account, SavingsAccount, OverdraftAccount and CityBank of the previous assignment ie. Assignment 14 under the package of this assignment. Step 2: Modify the CityBank.java as mentioned below (highlighted). /* * This java file is a starter class which instantiates the Account * class and call the corresponding methods for the various banking * operations. *//** * This class is a starter classes that instantiate the Account. * Using the instance, it invokes the corresponding banking * operations. * Date : <> * @author <> * @version 1.0 */public class CityBank { CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 37 of 68 /** * Instantiate the Account object. Call the corresponding methods that * does the various banking operations. * @param args the command line arguments */public static void main (String[] args) { //To-do: Create an instance (john) for Customer class. Call the overloaded constructor SavingsAccount johnSA = new SavingsAccount(101,john,1000); //To-do: call transaction(johnSA,1000) of CityBank //To-do: call the method to withdraw Rs.1600. //To-do: display the balance available. //To-do: Create an instance (jenny) for Customer class. Call the overloaded constructor OverdraftAccount jennyOA = new OverdraftAccount(201,jenny,500,2000); //To-do: call transaction(jennyOA,1500) of CityBank //To-do: display the balance available in account no 201 Note: available balance for Current Account is balance+ Allowed negative amount //To-do: call the method to withdraw Rs. 1000 to A/c No 201 //To-do: display the balance available of 201 //To-do: call the method to withdraw Rs. 4000 to A/c No 201 //To-do: display the balance available of 201 //To-do: call the method to withdraw Rs. 3000 to A/c No 201 //To-do: display the balance available of 201 } //To-do: Add the /** .. */comment for the method public void transaction(Account account, double amount) { account.deposit(amount); } }  Fix the compilation error in CityBank.java Step 3: Compile and execute the program. You should get the same output as that of Assignment 19. Try to understand how the program works. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 38 of 68  The compiler, while compiling the program, would find the class for which the reference variable is declared. The compiler also checks whether the class has method which is being invoked.  In this case, the account is a reference variable for Account class. Account class does not have a method withdraw. Hence, the compiler shows an error within transaction method.  At the time of execution, the run-time environment identifies the type of the object that the reference variable is pointing to. The run-time environment invokes the method defined in the class of the object, the reference variable is pointing to.  In the case of transaction(johnSA,1000), the type of the object that the reference variable account pointing to is “SavingsAccount”. The SavingsAccount inherits the deposit method from Account. Hence, the deposit method in Account would be invoked automatically. Step 4: Modify the transaction() method of CityBank to call the withdraw() method, as shown below. public static void transaction(Account account, double amount) { account.deposit(amount); account.withdraw(100); } Step 5: Compile the program and try to understand the compilation error.  In this case, the account is a reference variable for Account class. Account class does not have a method withdraw. Hence, the compiler shows an error. Step 6: Fix the error, by removing the account.withdraw(100) from transaction method. Step 7: Compile and execute the program. Summary of this exercise: You have just learnt  The concept of Dynamic binding and run-time polymorphism. Assignment 16: Understanding Abstract class Objective: To understand the concept of abstraction (abstract method and abstract class). CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 39 of 68 Problem Description: Introducing the abstract method and abstract class in CityBank application. Estimated time: 30 Mins. Step 1: Make a copy of Customer, Account, SavingsAccount, CurrentAccount and CityBank of the previous assignment i.e., Assignment 15 under the package of this assignment. Abstract method:  A method can be declared as abstract in the super class, if the method cannot be defined within the super class, but needs to be defined within the sub class. By declaring a method abstract, you are forcing the subclass to define the method. Abstract class:  A class can be declared as abstract in two circumstances. One, if the class has any of the method declared as abstract. Other being, If you don‟t want to instantiate the class but you want to instantiate the subclass. Note: Object cannot be instantiated for the abstract class, where as the reference variable can be declared for the abstract class. Step 2: In CityBank application, the programmer should not create an object for the class Account. (In real world, we have either Savings Account or Current Account. There cannot be simply be an account. Similarly, there is nothing called vehicle existing in the real world. It would be an instance of car, bike, or other type of vehicles. ) Step 3: Modify the Account class by declaring Account class as abstract. Step 4: Compile all the programs and execute. Step 5: Modify CityBank.java as given below. /* * This java file is a starter class which instantiates the Account * class and call the corresponding methods for the various banking * operations. *//** * This class is a starter classes that instantiate the Account. * Using the instance, it invokes the corresponding banking * operations. * Date : <> * @author <> * @version 1.0 */CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 40 of 68 public class CityBank { /** * Instantiate the Account object. Call the corresponding methods that * does the various banking operations. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create an instance (john) for Customer class. Call the overloaded constructor Account account = new Account(); SavingsAccount johnSA = new SavingsAccount(101,john,1000); //To-do: call transaction(johnSA,1000) of CityBank //To-do: call the method to withdraw Rs.1600. //To-do: display the balance available. //To-do: Create an instance (jenny) for Customer class. Call the overloaded constructor CurrentAccount jennyOA = new CurrentAccount(201,jenny,500,2000); //To-do: call transaction(jennyOA,1500) of CityBank //To-do: display the balance available in account no 201 Note: available balance for Current Account is balance+Allowed negative amount //To-do: call the method to withdraw Rs. 1000 to A/c No 201 //To-do: display the balance available of 201 //To-do: call the method to withdraw Rs. 4000 to A/c No 201 //To-do: display the balance available of 201 //To-do: call the method to withdraw Rs. 3000 to A/c No 201 //To-do: display the balance available of 201 } //To-do: Add the /** .. */comment for the method public static void transaction(Account account, double amount) { account.deposit(amount); } } Step 6: Save and compile the program. Step 7: Fix the compilation error, by removing the statement highlighted. Compile the program. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 41 of 68 Step 8: Also, as part of OOD, you have identified that the subclasses i.e. SavingsAccount and CurrentAccount should define the withdraw method. This can be enforced by declaring an abstract method in the Account class. Step 9: Modify the Account abstract to have an abstract method with the signature as follows. public abstract void withdraw(double amount);  The class should be declared as abstract, if any of the method is declared as abstract.  Account is already declared as abstract, according to step 3. Step 10: Compile and execute the program. Step 11: Try to comment the withdraw method in SavingsAccount and compile the program. You would get compilation error. Step 12: Un-comment the withdraw method. Save, compile and execute CityBank.java Summary of this exercise: You have just learnt  Abstract method  Abstract class Assignment 17: Understanding Dynamic Binding Objective: To understand and revisit dynamic binding, run-time polymorphism and its usages. Problem Description: Making the CityBank.java to implement the dynamic binding and run-time polymorphism. Estimated time: 20 Mins. Step 1: Make a copy of Customer, Account, SavingsAccount and OverdraftAccount of the previous assignment i.e. Assignment 16 under the package of this assignment. Step 2: Create a class CityBank, as shown below. /* * This java file is a starter class which instantiates the Account * class and call the corresponding methods for the various bank * operation. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 42 of 68 *//** * This class is a starter classes that instantiate the Account. * Using the instance, it invokes the corresponding banking * operations. * Date : <> * @author <> * @version 1.0 */public class CityBank { /** * Instantiate the Account object. Call the corresponding methods that * does the various banking operations. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create an instance (john) for Customer class. Call the overloaded constructor SavingsAccount johnSA = new SavingsAccount(101,john,1000); //To-do: call transaction(johnSA,1000) of CityBank //To-do: display the balance available. //To-do: Create an instance (jenny) for Customer class. Call the overloaded constructor CurrentAccount jennyOA = new CurrentAccount(201,jenny,500,2000); //To-do: call transaction (jennyOA,1500) of CityBank //To-do: display the balance available in account no 201 Note: available balance for Overdraft Account is balance+ Allowed negative amount } //To-do: Add the /** .. */comment for the method public static void transaction(Account account, double amount) { account.deposit(amount); account.withdraw(100); } } Step 3: Compile and execute the program. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 43 of 68  Now, you are able to call the deposit as well withdraw within transaction method, because the Account class has the definition of deposit as well the declaration of withdraw method. Summary of this exercise: You have just learnt  The concept of Dynamic binding and run-time polymorphism. Assignment 18: Understanding Interface Objective: To understand the concept of interface. Problem Description: Create classes for different animals like Lion, Hippo, Dog, Cat. Estimated timed: 20 mts Step 1: Perform OOA Step 2: Perform OOD. You should be able to identify the commonality among the nouns. Hence, you derive at the super class Animal. Dog and Cat again has come commonality as both are pet animals. Hence you can introduce the concept of generalization here. But, the Dog and Cat is already inheriting from Animal. Hence PetAnimal cannot be a class. Make PetAnimal as Interface. The pet animals would have the functionality of being friendly and playing with the human beings. Based on these, design the classes, its properties (if any) and functionalities. Step 3: Implement the Animal, Hippo, Dog, Cat classes and the PetAnimal Interface. Step 4: Make sure the Dog and Cat are inheriting from both Animal class as well from Pet interface. Create all the below mentioned classes and interfaces according to the standards. public interface PetAnimal { } public class Animal { } public class Hippo extends Animal { CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 44 of 68 } public class Dog extends Animal implements PetAnimal { } public class Cat extends Animal implements PetAnimal { } Step 5: Save all and compile. Execute the program. Summary of this exercise: You have just learnt  The concept of Interface in Inheritance Assignment 19: Understanding Packages Objective: To understand the package concept. Problem Description: Organizing the classes and interfaces of CityBank application into packages. Estimated time: 20 Mins. Note: All package names must start with a lower case letter Step 1: Create a package with name com.Citybank.customer. Modify the Customer class of Assignment4, so that it belongs to the package com.Citybank.customer. Make sure the class and the constructor(s) are declared as public. Step 2: Compile Customer.java. Fix the errors, if any. Step 3: Create a package with name com.Citybank.account. Add the Account, SavingsAccount, CurrentAccount to the package com.Citybank.account. Modify Account class, so that it imports the Customer class belonging to com.Citybank.customer package. Make sure all the classes and constructors are declared as public. Otherwise you will not be able to access the class outside the package. Step 4: Create a package with name com.Citybank. Add the CityBank to the package com.Citybank. Make sure the class and constructor(s) are declared as public. Import the relevant classes and the packages. Step 5: Compile all the classes and fix the errors, if any. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 45 of 68  There won‟t be any error related to locating the package, be it com.Citybank.customer or com.Citybank.account. Try to find why the java compiler /run-time do not throw any error. Step 7: Execute the com.Citybank.CityBank from the package where the package is stored. Summary of this exercise: You have just learnt  The concept of Dynamic binding and run-time polymorphism. Assignment 20: Understanding the Access Specifier Objective: To understand the concept of Access specifiers. Problem Description: Create classes in different packages and try to access variables with different access specifiers. Estimated time: 20 Mins. Step 1: Create a package „package1‟ Step 2: Create two classes Base, Child1 under package1 as given below. Base.java package package1; /* * This java file is a class which has 4 member variables * with different access specifiers *//** * This class is a class that has 4 member variables * with different access specifiers * It also has 2 methods to access the variables * Date : <> * @author <> * @version 1.0 */public class Base { int variable1; private int variable2; protected int variable3; CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 46 of 68 public int variable4; /* * Default Constructor that initializes the member variables */Base () { variable1=100; variable2=200; variable3=300; variable4=400; } /* * Returns the value of the member variable variable1 */int getVariable1(){ return variable1; } /* * Returns the value of the member variable variable2 */public int getVariable2(){ return variable2; } } Child1.java package package1; /* * This java file is a class which is a sub class * of Base class *//** * This class is a class which extends Base class * It has a method that gets the values of the * member variables of Base class * Date : <> * @author <> * @version 1.0 */CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 47 of 68 public class Child1 extends Base{ public void getValues() { System.out.println (getVariable1()); System.out.println (getVariable2()); System.out.println (variable3); System.out.println (variable4); } } Step 3: Compile all the classes. Fix the errors.  Members declared without any access specifier is default. They can be accessed only within the same package  Members declared as private can be accessed only within the class  Members declared as protected can be accessed within the class and also by sub classes in a different package  Members declared as public can be accessed anywhere Step 4: Create a package package2 Step 5: Create a class Child2 under package2 as given below. Child2.java package package2; /* * This java file is a class which is another sub class * of Base class */import package1.Base; /** * This class is a class which extends Base class * It has a method that gets the values of the * member variables of Base class * Date : <> * @author <> * @version 1.0 */public class Child2 extends Base{ public void getValues() { Base base=new Base(); System.out.println (variable3); //Line 1 CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 48 of 68 System.out.println (base.variable3); //Line 2 System.out.println (variable4); } } Step 6: Compile Child2.java. Fix the errors.  Though protected members can be accessed in sub classes in different package, it can be accessed only through inheritance  That is it can be accessed as if it belongs to the same class (Like in Line 1)  When accessed using an object, it acts as if it is a private variable (So, Line 2 will throw a compile time error) Step 7: Compile all the programs and execute the program. Summary of this exercise: You have just learnt  To declare variables with different access specifiers and where it can be accessed. Assignment 21: Garbage Collection Objective: To understand the concept of memory allocation and how garbage collection takes place in Java. Problem Description: Draw the stack and heap representation for the following class. And identify how many objects are created on heap Estimated time: 20 Mins. class Tyre{} public class Car { Tyre tyre; String name; public static void main(String[] args) { Car carMain = new Car(); carMain.setFeatures(carMain); } void setFeatures(Car car) { tyre = new Tyre(); car.setName("Swift"); } void setName(String name){ this.name = name; } } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 49 of 68 setName() name setFeatures() car main() carMain Overall three objects are created on the Heap. Summary of this exercise: You have just learnt  How memory allocation takes place on heap and stack Assignment 21a: Garbage Collection Objective: To understand the concept of memory allocation and how garbage collection takes place in Java. Problem Description: Draw the stack and heap representation for the following class. And identify how many objects will be created on heap Summary of this exercise: Heap String Object: “Swift” Tyre object Car object: Instance variables: name tyre Stack public class Vehicle { String vehicleName; Wheels [] wheels = new Wheels [4] ; public static void main(String[] args) { Vehicle vehicle = new Vehicle(); } } class Wheels{} CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 50 of 68 You have just learnt  How memory allocation takes place on heap and stack Assignment 21b: Garbage Collection Objective: To understand the concept of memory allocation and how garbage collection takes place in Java. Problem Description: Analyze the following code example and tell how many objects will be garbage collected after a. Line 1 b. Line 2 c. Line 3 Before solving the above parts of the problem, find the total number of objects that will be created on heap just before the start of line 1. Ans : a. after line 1: 0 Objects will be garbage collected b. after line 2: 2 Objects will be garbage collected c. after line 3: remaining 2 Objects will be garbage collected. Summary of this exercise: You have just learnt  To understand the how the stack and heap work together  How to analyze a code to predict the number of objects created on the heap. public class Garbage { String garbageLocation; Garbage garbage; public static void main(String[] args) { Garbage garbage1 = new Garbage(); garbage1.garbage = new Garbage(); garbage1.garbageLocation="Hyderabad"; garbage1.garbage.garbageLocation="Kukatpally"; garbage1.garbage.garbage=garbage1; garbage1.garbage.garbage = null ; //line 1 garbage1.garbage= null; //line 2 garbage1 = null; //line 3 } } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 51 of 68  How to predict the number of objects that are eligible for garbage collection. 5 Assignments for Day 3 Java Programming Assignment 22: Autoboxing and unboxing Objective: To understand the autoboxing and unboxing concept. Problem Description: Write a class to store the list of employee id‟s belonging to a particular project in a vector. Assume that employee from 1001 to 1005 has been assigned a project in CityBank account. Estimated time: 15 Mins. Step 1: Create a class Employee based on the below given requirements. /* * To-do: <> *//** * <> * Date : <> * @author <> * @version 1.0 */public class EmployeeInfo{ /** * To-do: << Replace with appropriate description >> */public static void main (String[] args) { //Vector is in java.util package. Refer javaDocs Vector empList = new Vector(); int empNo=1000; for(int count=0;count<5;count++) { empNo++; //Only object can be added to the vector. //Convert the int to Integer CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 52 of 68 //To-do: add the empNo to the vector } //To-do: retrieve and display the elements in vector } } Step 2: Complete the above program and execute the same. Step 3: Modify the above program to use the concept of autoboxing and unboxing, which would simplify the program. Also, use enhanced for loop to retrieve and display the elements in the vector. Step 4: Compile and execute the program. Summary of this exercise: You have just learnt  The concept of Autoboxing and unboxing. Assignment 23: Understanding Exception Handling (Unchecked Exceptions) Objective: To understand how to handle the exceptions. Problem Description: A program that would handle the NullPointerException with try and catch block. Estimated time: 30 Mins. Step 1: Create a starter class with the name ExceptionHandlingDemo. Step 2: Write the below given code in the main method of the starter class. String name; System.out.println(name.length()); name = "John"; System.out.println(name.length()); Step 3: Compile the program. Step 4: Fix the error as shown below. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 53 of 68 String name = null; System.out.println(name.length()); name = "John"; System.out.println(name.length()); Step 5: Compile the program. Step 6: Execute the program and note the exception.  NullPointerException is an unchecked exception. The compiler would check only for the checked exceptions.  Refer to JavaDoc for further information about NullPoninterException. Step 7: Modify the program to handle the run-time exception, as given below. String name = null; try{ System.out.println(name.length()); } catch(NullPointerException exception){ System.out.println("Object is null"); } System.out.println(“Continuing the execution...”); Step 8: Now, execute the program. As the exception raised is handled in the program, the program does not terminate abruptly, as happened in step 6. Step 9: Modify the code as given below. String name = null; try{ System.out.println(name.length()); System.out.println(“End of try block”); } catch(NullPointerException exception){ System.out.println("Object is null"); } System.out.println(“Continuing the execution...”);  If a statement in the try block, throws an exception, the following statements in the try block would not be executed.  Hence, System.out.println(“End of try block”); is not executed, when name.lenght() throws NullPointerException. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 54 of 68 Step 10: Compile and execute the program. Step 11: Modify the code as given below. String name = null; int total = 100,count=0; try{ int average = total/count; System.out.println(average); System.out.println(name.length()); } catch(NullPointerException exception){ System.out.println("Object is null"); } System.out.println(“Continuing the execution...”); Step 12: Execute the program and understand the output. Step 13: Modify the program as given below. String name = null; int total = 100,count=0; try{ int average = total/count; System.out.println(average); System.out.println(name.length()); } catch(ArithmeticException exception) { System.out.println("Arithmetic Exception " + exception.getMessage()); } catch(NullPointerException exception){ System.out.println("Object is null"); } System.out.println(“Continuing the execution...”); Step 14: Execute and analyze the cause of this output. Summary of this exercise: You have just learnt  The fundamental of exception handling CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 55 of 68 Assignment 24: Understanding Exception Handling – try, catch & finally Objective: To understand how to handle the exceptions – try, catch and finally block. Problem Description: A program that would handle the NullPointerException with try, catch and finally block. Estimated time: 15 Mins. Step 1: Make a copy of the ExceptionHandlingDemo.java in Assignment 23, under the package of this assignment. Step 2: Modify the program as given below. String name = “john”; int total = 100,count=10; try{ int average = total/count; System.out.println(average); System.out.println(name.length()); } catch(ArithmeticException exception) { System.out.println("Arithmetic Exception " + exception.getMessage()); } catch(NullPointerException exception){ System.out.println("Object is null"); } finally{ System.out.println(“within finally block”); } System.out.println(“Continuing the execution...”); Step 3: Compile, execute and analyze the output.  finally block would get executed, even if the try block throws exception. The finally block should be used to release the resources that you have locked within the application.  For e.g. you might have opened a file within the try block. It is always advisable to close the file in the finally block, because the finally block would be executed definitely irrespective of the exceptions. Step 4: Change the value of count to 0. Compile and execute the program. Analyze the output. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 56 of 68 Step 5: Try to analyze the different cases associated with finally block. Especially when the code in finally will be executed and when it will not. Summary of this exercise: You have just learnt  The fundamental of exception handling (try, catch and finally) Assignment 25: Understanding Exception Handling (Checked Exceptions) Objective: To understand how to handle the checked exceptions – try, catch and finally block. Problem Description: Write a program that would handle the ClassNotFoundException with try, catch and finally block. Estimated time: 15 Mins. Step 1: Create a class named ExceptionDemo with the static block given below, under the package com.exception. static { System.out.println(“In the static block of ExceptionDemo..”); } Step 2: Create a starter class named CheckedExceptionDemo under the package com.exception. Step 3: Make the CheckedExceptionDemo program to load the ExceptionDemo class at run-time.  class Class has a method named “forName”, which loads any given class at run-time. public static void main(String arg[]) { Class.forName(“com.exception.ExceptionDemo”); } Step 4: Save and compile the program. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 57 of 68  The compiler throws an exception in Class.forName(..). The forName method of Class, throws checked exception – ClassNotFoundException. The compiler expects the programmer to handle the checked exception. Step 5: Modify the method as shown below. public static void main(String arg[]) { try{ Class.forName(“com.exception.ExceptionDemo”); } catch(ClassNotFoundException exception){ System.out.println(“Exception : “ + exception); } } Step 6: Compile and execute the program.  To get to know about whether the method throws any checked exception, refer to the java doc. All those methods mentioned in the throws clause of the method signature are checked exceptions.  E.g. refer to the method signature of forName of Class. Summary of this exercise: You have just learnt  To handle the checked exceptions Assignment 26: Understanding User defined Exception Handling Objective: To understand how to handle the user-defined exceptions. Problem Description: The withdrawal method of SavingsAccount and OverdraftAccount should raise an exception, if the balance is not sufficient for withdrawl. Estimated time: 15 Mins. Step 1: Make a copy of Account, SavingsAccount, CurrentAccount and CityBank programs from Assignments of Day 2 under the package of this assignment. Step 2: Create User defined exception class, InsufficientBalanceException, as shown below. /* CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 58 of 68 * To-do: <> *//** * <> * Date : <> * @author <> * @version 1.0 */public class InsufficientBalanceExcpetion extends Exception { /** * To-do: << Replace with appropriate description >> */public InsufficientBalanceException(){ super("Sufficient Balance not available"); } } Step 3: Modify the withdraw method of both SavingsAccount as well OverdraftAccount to throw the exception public void withdraw(double amount) throws InsufficientBalanceException { //logic to check the sufficient balance //if (availablebalance <= amount) throw new InsufficientBalanceException(); //else //Update the balance } Step 4: Modify the CityBank program to handle the exceptions. try { //johnSA.withdraw(amount); //johnSA. } catch (InsufficientBalanceException e) { System.out.println(e.getMessage()); } Step 5: Similarly modify the code every time you invoke the withdraw method. Step 6: Compile all the programs and execute it. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 59 of 68 Summary of this exercise: You have just learnt  To handle the user defined exceptions  To handle the exception 3 Assignments for Day 4 Java Programming Assignment 27: JavaBeans Objective: To understand how to create JavaBeans using Eclipse IDE. Problem Description: Create a EmployeeBean class named Employee under the package of this assignment. Employee should contains following fields: Step 1: select all the fields and right click, you will get a floating menu. Step 2: From the floating menu select source and then select Generate Getters and Setters and the same are highlighted in the screenshot above. After you select, you will get a window like this. public class Employee{ int employeeID; String employeeName; Calendar dateOfBirth; } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 60 of 68 Step 3: select the checkboxes for the fields for which you want to generate the getters and setters. From the right you can select different options of generating only setters or getters. Then click ok. Step 4: Save and compile the bean class Summary of this exercise: You have just learnt  How to create JavaBeans using Eclipse IDE Assignment 28: Creating (Java Bean) Classes and Object Objective: To understand what is java bean and how to create a java bean class and instantiate it in another class. Problem Description: Create a Customer (Bean) class with instance variables customerID, customerName, address and pinCode. Create another starter class and instantiate Customer bean object in it. Estimated time: 15 Mins. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 61 of 68 Step 1: Create a Java Bean Class – Customer according to the below given class diagram. Save the file as Customer.java under the package of the assignment. Customer -customerId : int -customerName : String -customerAddress : String -pincode : int + setCustomerId(int custId) : void + getCustomerId() : int + setCustomerName(String custName) : void + getCustomerName() : String + setCustomerAddress(String custAddress) : void + getCustomerAddress() : String + setPincode(int pin) : void + getPincode() : int Java Bean:-Java Bean is defined as a reusable component. A java bean class should adhere to the following rules.  All the member variables should be declared private  (Almost) All the member variables should have the Getter and Setter methods o Setter Method is to set the value for the corresponding member variable. o Getter Method is to retrieve the value stored in the corresponding member variable.  Name of the Getter & Setter method should match the variable name o E.g, member variable : customerName (according to the java naming convention the variable should follow camel-casing. Hence first letter should be in lower case) Setter Method Name : setCustomerName  Constructor need not be defined Step 2: Create a starter class with name “CityBank”. Filename CityBank.java /* * This java file is a starter class which instantiates Customer bean * and call the corresponding setter (to assign values) and getter * methods (to retrieve the values and display it)from the main method *//** * This class is a starter classes that instantiate the Customer bean. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 62 of 68 * Using the instance, it calls the setter to set the member variables * and the getter method to display the values * Date : <> * @author <> * @version 1.0 */public class CityBank { /** * Instantiate the Customer bean. Set the values for the member * variables and get the values and display the same. * @param args The command line arguments */public static void main (String[] args) { //To-do: Create an instance (john) for Customer class. //Set the values of all the member variables for „john‟ john.customerId = 101; //To-do: Set the values for all the other member variables //Retrieve the values and display it System.out.println(john.customerId); //To-do: Retrieve and display all the other member variables } } Step 3: Try to Compile the CityBank.java. Read the compilation error and try to fix it.  The java compiler would list compilation errors like “customerId has private access in Customer” for customerId and similar error for other member variables. If those compilation errors are not listed, then the Customer class has not been created according to the class diagram. Check whether all the member variables are declared as „private‟. Modify Customer.java accordingly and recompile the code.  The customerId is private in Customer class. The private members can be accessed only within the class. According to the OO concept (refer to encapsulation and data hiding concept in the slide), the member variables cannot be declared as public. The only way to access the member variable is through the setter and getter methods. Step 4: Modify the CityBank.java accordingly. CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 63 of 68  Use john.setCustomerId(101) – to set the value for the member variable  Use john.getCustomerid() – to retrieve the value and display the same in CityBank Similarly, call the corresponding methods of all the member variables. Step 5: Save the program. Compile it. Fix all the errors, if any. Step 6: Execute the CityBank class and check the output. Summary of this exercise: You have just learnt  Java Beans  Creating object of one class in another class  How to access member variables of an object Assignment 29: Usage of ‘this’ keyword Objective: To understand the usage of „this‟ keyword. Problem Description: Create a Customer (Bean) class with instance variables customerID, customerName, address and pinCode and use the „this‟ to represent the current object within the member methods. Estimated time: 15 Mins. Step 1: Make a copy of Customer.java and CityBank.java of Assignment 28, under the package of this assignment. Step 2: Alter the class according to the below given class diagram. Customer -customerId : int -customerName : String -customerAddress : String -pincode : int + setCustomerId(int customerId) : void + getCustomerId() : int + setCustomerName(String customerName) : void + getCustomerName() : String + setCustomerAddress(String customerAddress) : void + getCustomerAddress() : String CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 64 of 68 + setPincode(int pincode) : void + getPincode() : int  The parameter name of the setter methods is different from Assignment 8. You have to change the variable name used within the setter methods to match the member variable names. e.g. public void setCustomerId(int customerId) { customerId = customerId; } Step 3: Compile Customer.java. Fix the errors if any. Step 4: Compile CityBank.java and fix the errors if any. Step 5: Execute CityBank.java.  Do you get the default value for all the properties? Try to analyze the output public void setCustomerId(int customerId) { customerId = customerId; }  The value of the local variable customerId is assigned to the local variable itself, instead of the member variable customerId. Step 6: Do the necessary modification in the Customer class, so that the values get initialized to the member variables rather than the local variables themselves.  Alter the setter definition in Customer as follows. public void setCustomerId(int customerId) { this.customerId = customerId; }  this.customerId, „this‟ – refers to the current object i.e. john. Hence the value of the local variable customerId is assigned to john‟s customerId. Similarly change the definition for all the setter methods. Step 7: Compile Customer.java. Fix the errors, if any. Step 8: Execute CityBank. Check whether the program displays the Customer Id, Name, address and pincode of john. Summary of this exercise: You have learnt  Usage of „this‟ CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 65 of 68 Assignment 30: Understanding Collection Framework Objective: To understand the Collection framework. Problem Description: A program to store the employee object in the ArrayList. Estimated time: 20 Mins. Step 1: Create a EmployeeBean class named Employee under the package of this assignment. Employee contains following fields: Note: you can use the EmployeeBean created as a part of earlier assignment. Step 2: Create a starter class named EmployeeInfo under the package of this assignment as shown below. Step 3: Change the class to retrieve the records using forEach loop not an iterator Summary of this exercise: You have just learnt  Basics of the collection framework using ArrayList and List. Assignment 31: Reflection API Objective: To understand the basics of reflection API. int employeeID; String employeeName; Calendar dateOfBirth; public class EmployeeInfo { public static void main(String[] args) { //To-Do : create four employee objects //To-Do : store the objects in the ArrayList /* [ HINT :] * Employee employee1 = new Emlpoyee(); * employee1.employeeID = 1001 ; * List list = new ArrayList(); * list.add(employee1); *///To-Do : retrieve the employee objects from the list using iterator and display their information } } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 66 of 68 Problem Description: To analyze a class using Reflection API Estimated time: 20 Mins. Step 1: Copy the class file of the Employee bean in the current package of this assignment. Step 2: Create a TestReflection.java in the current package of the assignment. Class will look something like this.  When you will save (+compile) the file. You will get a checked exception ClassNotFoundException because the Class.forName() is a static method which throws ClassNotFoundException. Step 3: Make the above code compile, put the above code in the main in try-catch block or use throws clause with the main. Step 4: Replace the comments with actual code that is required to collect information about the fields and methods in the Employee class. Summary of this exercise: You have just learnt  How to use Reflection API import java.lang.reflect.*; public class TestReflection { public static void main(String[] args) { Class classObj = Class.forName("Employee"); } } try { Class classObj = Class.forName("Employee"); //To-Do : write code to collect the method information-name and parameters //To-Do : write code to collect field information -access specifiers and data types } catch (ClassNotFoundException e) { e.printStackTrace(); } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 67 of 68 Assignment 32: Annotations Objective: To understand the basics of reflection API. Problem Description: Use @Deprecated annotation to make the function of a class deprecated. Estimated time: 15 Mins. Step 1: Create a java class as shown below Step 2: Create a java class to test the above class as shown below public class StringMock { String capacity; public StringMock(){ } public StringMock(String capacity){ this.capacity=capacity; } /** Description: method returns the position of the character if * char to be searched is present in the String otherwise it * returns -1 * @param string * @param searchItem * @return int */@Deprecated public static int search(String string,char searchItem){ //declare loop variable int index ; //convert the string to char array char [] charArray = string.toCharArray(); //iterate over the char array to search for the character for(index=0; index < charArray.length; index ++){ if(charArray[index]==searchItem) return index; } return -1 ; } } public class TestStringMock { public static void main(String[] args) { String message = "What's in the name"; //To-Do : create an object of StringMock class //To-Do : Use search method to search for a character present in the array //To-Do : Use search method to search for a character not present in the array } } CommunicationTeam.org Lab Guide for Java Programming Version No. 1.0 68 of 68  You will see that the method with which you gave @Deprecated annotation will come as deprecated when you are using it. Likewise fields and even class can be made as deprecated Summary of this exercise: You have just learnt  Basics of built-in annotations