Why does it still have it as "Null"?

[cart1443]

So why are the different instructor names showing up as "null" when the course name doesn't? They are formatted the same. Am I missing something?

PHP Code:

// Lab 2: GradeBook.java
// GradeBook class with a constructor to initialize the course name.

public class GradeBook
{
   private String courseName; // course name for this GradeBook
   /* write code to declare a second String instance variable */
   private String InstructorName;
   
   // constructor initializes courseName with String supplied as argument
   public GradeBook( String name ) 
   {  
      courseName = name; // initializes courseName 
   } // end constructor 

   // method to set the course name
   public void setCourseName( String name )
   {
      courseName = name; // store the course name
   } // end method setCourseName

   // method to retrieve the course name
   public String getCourseName()
   {
      return courseName;
   } // end method getCourseName

   /* write code to declare a get and a set method for the instructor’s name */
   public void setInstructorName( String Iname )
   {
      InstructorName = Iname; // store the course name
   } // end method setCourseName

   // method to retrieve the course name
   public String getInstructorName()
   {
      return InstructorName;
    }
   
    // display a welcome message to the GradeBook user
   public void displayMessage()
   {
      // this statement calls getCourseName to get the 
      // name of the course this GradeBook represents
      System.out.printf( "Welcome to the grade book for\n%s!\n\n", 
         getCourseName() );
      System.out.printf( "This course is presented by: %s!\n", 
         getInstructorName() );
      /* write code to output the instructor’s name */
   } // end method displayMessage

} // end class GradeBook 


PHP Code:

// Lab 2: GradeBookTest.java
// GradeBook constructor used to specify the course name at the 
// time each GradeBook object is created.

public class GradeBookTest
{
   // main method begins program execution
   public static void main( String args[] )
   { 
      // create GradeBook object
      GradeBook gradeBook1 = new GradeBook("CS101 Introduction to Java Programming" );
      GradeBook Iname1 = new GradeBook("Sam Smith");
      GradeBook Iname2 = new GradeBook("Judy Jones");

      gradeBook1.displayMessage(); // display welcome message
      
      /* write code to change instructor’s name and output changes */
      
      Iname2.setInstructorName(Iname2.getInstructorName());
      System.out.printf("\nChanging instructor name to %s", 
            Iname2.getInstructorName() );
   } // end main

} // end class GradeBookTest 


[hardwired]

The only way to set the name for the instructor is with the setInstructorName method which you did not use in your main method. Your only GradeBook constructor requires a String argument whose value is assigned to the "courseName" member variable. The member variable "InstructorName remains null until you assign it a value via the setInstructorName method.

Code:

   public static void main( String args[] ) 
   {  
      GradeBook Iname1 = new GradeBook("Sam Smith"); 
      Iname1.setInstructorName("John Stuart");
      // Now it won't be null for the "Iname1" instance.
      ...