How many objects are there in this picture? How many reference variables are there in this picture?

A good answer might be:

There are two objects, and two reference variables, each containing a different reference.

The == operator is used to look at the contents of two reference variables. (This operator is two equal signs in a row.) If the contents of both reference variables is the same, then the result is true. Otherwise the result is false.

The == operator does NOT look at objects! It only looks at references (information about where an object is located.)

Here is a section from the previous program, with an additional if statement:

    String strA;  // reference to the first object
    String strB;  // reference to the second object
     
    strA   = new String( "The Gingham Dog" );    // create the first object and  
                                                 // save its reference
    System.out.println( strA   ); 

    strB   = new String( "The Calico Cat" );     // create the second object and
                                                 // save its reference
    System.out.println( strB   );

    if ( strA == strB ) 
      System.out.println( "This will not print.");

Since the reference in strA is different than the reference in strB,

    strA == strB

is false. (Look at the picture on the previous page.) The third output statement will not execute.

QUESTION 13:

Did the == operator look at the contents of the objects when the if statement executed?