A good answer might be:

A single reference variable car is used in turn for each object.


Junked Car

The output to the screen of this program is the same as the previous. However, since the reference variable car is used when the second Car is constructed, the first car becomes garbage before the end of the program.

Car car  = new Car( 32456, 32810, 10.6 );
System.out.println( "Miles per gallon of car 1 is " 
  + car.calculateMPG() );

car      = new Car( 100000, 100300, 10.6 );
System.out.println( "Miles per gallon of car 2 is " 
  + car.calculateMPG() );

The picture shows the situation just after the second car is constructed. The first car no longer has a reference to it, so it is now garbage.



QUESTION 16:

(Review Questions:)

  1. Do the instance variables of an object hold values for the lifetime of the object?
  2. Do the parameters of a constructor hold values for the lifetime of the object?