Using a Temporary Object

In the example program, a String object was created, and a reference to it was kept in a reference variable. This worked, but was a bit awkward. Here is another modification to the example program:

import java.awt.*;
class PointEg3
{

  public static void main ( String arg[] )
  {
    Point a = new Point();              // declarations and construction combined 
    Point b = new Point( 12, 45 );    
    Point c = new Point( b );

    System.out.println( a.toString() ); // create a temporary String based on "a"
  }
}

This program creates three Points with the same values as before, but now the declaration and construction of each point is combined.

The last statement has the same effect as the last two statements of the previous program:

1. When the statement executes, a refers to an object with data (0,0).
2. The toString() method of that object is called.
3. The toString() method creates a String object and returns a reference to it.
4. At this point of the execution, you can think of the statement like this:

   System.out.println( reference to a String );

5. The println method of System.out uses the reference to find the data to print out on the monitor.
6. The statement finishes execution; the reference to the String has not been saved anywhere.

Since the String reference was not saved in a reference variable, there is now no way to find it. It is garbage. That is OK. It was only needed for one purpose, and that purpose is completed. Using objects in this manner is very common.