Can a constructor be used to change the data inside an object?
No. Constructors always create new objects. (They might get data from an old object, but a completely separate object will be constructed using a different chunk of main memory.)
Here is the example program, this time modified to create a second Point
object:
import java.awt.*; class ChangingData2 { public static void main ( String arg[] ) { Point pt = new Point( 12, 45 ); // construct a Point System.out.println( "First values: " + pt ); pt = new Point( -13, 49 ) ; // construct a new Point System.out.println( "Final values: " + pt ); } }
Here is a picture showing the situation before and after the second assignment statement:
In the "After" picture, the first object is shaded to
emphasis that it is now "garbage."
The reference variable pt
refers to the newly created object.
What will this second version of the program output to the monitor?