Objectives

• Demonstrate your ability to use a class given the public interface
• Construct and use Objects
• Modify the behavior of a class
  

Hand-in Requirements

All projects and laboratories will be submitted electronically through webCT.  Zip up your entire project directory to submit as the source.  (Right click on the project folder and follow the SentTo link.)  The project directory should include the following:

• Public Interface as a word or plaintext document
• BirthdaySong.java
• BirthdaySongTest.java

Details

You will modify a class named BirthdaySong.  This class has a method named sing that prints the words for Happy Birthday.  However this song does not mention the name of the birthday person.  We would like it to sing to a person that the client designates.  Your job will be to test and modify this class.

public class BirthdaySong {  

  // Constructor
  public BirthdaySong() {  

  }

  public void sing() {
      System.out.println("Happy birthday to you");  
      System.out.println("Happy birthday to you");
      System.out.println("Happy birthday dear ");
      System.out.println("Happy birthday to you");
  }

}

Part 1:  Write the public interface for the BirthdaySong class and be sure to add comments to each method

Part 2:  Setup:

• Project/Folder name:  BirthdaySong
• New class with main method:  BirthdaySongTest

  public class BirthdaySongTest {
      public static void main(String[] args) {
  
      }
  }
  

• Save the class in the BirthdaySong folder.
• Download the following file BirthdaySong.java and save in in the BirthdaySong folder.
• Open BirthdaySong.java in DrJava.
• Click on BirthdaySongTest in the Navigator pane (on the left).
• Compile and run.
• Save the project.

Part 3:  Modify and Test:

1. Test the BirthdaySong class.

   • Instantiate a BirthdaySong object named b1.
   • Have b1 print the song.
   After you have checked to see if your output is correct, comment out the above two lines using /*  and */

2. Modify the BirthdaySong class so that it sings the song to a person whose name is supplied by the client.

   • Add a private String instance variable myName.
   • Modify the constructor so that its parameter is String name and assign name to myName
   in the constructor.
   • Modify the sing method so that it uses myName.

     Happy birthday to you
     Happy birthday to you
     Happy birthday dear <myName here> !!!   
     Happy birthday to you
     

     Don't forget to print the !!!
   • Add a method setName that changes myName to a given name from the client.  The method stub would look like this:

     public void setName(String name) {
         // Your code here
     }
     

3. Test your modifications.

   • Instantiate a BirthdaySong object named b2 using the name "Grace" to sing to.
   • Have b2 sing.
   • Set the name for b2 to "Blaise"  using the setName method.
   • Have b2 sing again.
   • Set the name for b2 to "Alan" using the setName method.
   • Have b2 sing again.