Exercise 2: Creating a Test Program (Level 3)

In this exercise, you create a test harness (a test class) to exercise a pre-built class. These are the Level 3 instructions which provide additional hints with code snippets.

Task 1 - Creating the TestAccount Class

Using a text editor, create the TestAccount file. This class acts as a program to create an Account object with an initial balance of 100. The test program will then deposit 50 and then withdraw 147. Finally, the test program must print out the balance of the class to the standard output stream.

Perform the following:
  1. Declare the TestAccount class.

     public class TestAccount {
       //code here
     }

  2. Add the main method:

     public class TestAccount {
       public static void main(String[] args) {
         //code here
       }
     }
    1. Declare a variable of type Account and initialize that variable by creating an instance of the Account class with an initial balance of 100.

      Account acct = new Account(100.0);

    2. Use the deposit method to add 50 to the account.

      acct.deposit(50.0);

    3. Use the withdraw method to subtract 147 from the account.

      acct.withdraw(147.0);

    4. Use the getBalance method to retrieve the new accoutn balance and use the System.out.println method to display the balance to the standard output stream.

      System.out.println("Final account balance is " + acct.getBalance());

Task 2 - Compiling the TestAccount Program

On the command line, use the javac command to compile the test program.

javac TestAccount.java

Task 3 - Runnig th TestAccount Program

On the command line, use java command to run the test program.

java TestAccount

The output should be:

The final balance is 3.0