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EXAMPLE
Consider this Point class:
public class Point
{
public double x;
public
double y;
public Point(double
tmpx, double tmpy)
{
x = tmpx;
//setting x data field
y = tmpy;
//setting y data field
}
public Point()
{
x = 0.0;
y = 0.0;
}
}
We can add another constructor. Let's consider a constructor that gets a
Point object passed into it and uses that Point's x and y values to create
our new Point.
public Point(Point
tmp)
{
x = tmp.x;
y = tmp.y;
}
This constructor may seem strange at
first. To create a Point using this
constructor, one must first create the desired Point object. So what's the point (see what I did
there)?
Well, this constructor would provide us with the ability to clone a Point
object. It would allow us to make a
copy of another Point.
The following code tests the new
Point constructor:
public class Tester
{
public static void main(String[] args)
{
//Using constructor #1
Point p1 = new Point(3.4,
8.2);
//Using constructor #2
Point p2 = new
Point(p1);
System.out.println(p1.x
+ "," + p1.y);
System.out.println(p2.x
+ "," + p2.y);
}
}
It is important to note that p1 and
p2 are two completely different objects.
Changing p1 will not change p2.
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