equals and to string method

[Larry Lai]

Hi everyone,
How's everything? Busy in learning java?
A question is that I can use the equal and to string methods?
For example:
---------------------------------- | |
| public class Point |
| ------------------------------| |
| private doulbe x,y |
| |
| public Point (double x,y) |
| |
| public double x() |
| public doulbe y() |
| |
| public boolean equal(PointP) |
| |
| public String toString() |
| |
----------------------------------
1. How to write the 'equals() method?
2. How use the toString method that if the Point object had the coordinates(3,4) then the string "(3.0, 4.0)" would be returned.
3. if I need to use the equal() method, what would be the output of the following Java code fragement?
Point p = new Point (2, 3);
println("p.x() = " + p.x() + ", p.y()= " + p.y());
println ("p = " + p);
Point q = new Point (7, 4);
println ("q = " + q);
if (q.equals(p))
println ("q equals p");
else
println ("q does not equal p");
q = new Point (2, 3);
println ("q = " + q);
if (q.equals(p))
println ("q equals p");
else
println ("q does not equal p");
if (q == p)
println ("q == p");
else
println ("q != p");
I think it's a little bit hard ...anyone knows that how to solve that ?
Thanks
Larry

[doug shumway]

the default behavior, the equals method of object class, equates to true if both references point to the same object.
http://java.sun.com/products/jdk/1.1/docs/api/java.lang.Object.html
The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any reference values x and y, this method returns true if and only if x and y refer to the same object (x==y has the value true).
You can override the equals method within your class by using the reference passed to the equals
method
equals(Point p){
if ((this.x == p.x) && (this.y == p.x)){
return true;
}
else {return false;}
}
overriding the toString method
you can return whatever string or string concatenation you beleive to represent the objec

[Jim Yingst]

Please don't start the same topic in more than one forum; it wastes time for people who don't realize if something's already been answered elsewhere. Followups go here. Thanks...