Answer:
The different constructors require different parameters. (Different types of data are supplied to the constructors.)
Multiple Constructors
Any of the three constructors can be used to create a Point.
It is a matter of convenience which constructor you use.
Here is an example:
import java.awt.*; // import the package that contains Point
class PointEg1
{
public static void main ( String arg[] )
{
Point a, b, c; // reference variables
a = new Point(); // create a Point at (0, 0);
// save the reference in "a"
b = new Point( 12, 45 ); // create a Point at (12, 45);
// save the reference in "b"
c = new Point( b ); // create a Point containing data equivalent
// to the data referenced by "b"
}
}
To use the definition of class Point,
import the package that contains it.
The statement:
import java.awt.*
says to use the AWT package that comes with Java.
The * says that everything defined in the package can be used
(although this program only uses the Point class).
QUESTION 4:
Say that the program has just been loaded into main memory and is just about to start running.
How many reference variables are there?
How many objects are there?