Reference Variable Reused

Let us look at some of the details involved in doing this. Here is the program, again:

class EgString3
{
  public static void main ( String[] args )
  {
    String str;
     
    str   = new String("The Gingham Dog");
    System.out.println(str);

    str   = new String("The Calico Cat");
    System.out.println(str);
   }
}

Here is a diagram that shows the one reference variable str and the two objects. The variable can refer to only one object at a time. It first refers to the dog object, and then to the cat object.

Here are some details about how the reference variable and the two objects relate:

Statement	Action
str = new String("The Gingham Dog");	Create the FIRST object. Put a reference to this object into str
System.out.println(str);	Follow the reference in str to the FIRST object. Get the data in it and print it.
str = new String("The Calico Cat");	Create a SECOND object. Put a reference to the SECOND object into str. At this point, there is no reference to the first object. It is now "garbage."
System.out.println(str);	Follow the reference in str to the SECOND object. Get the data in it and print it.