diff b/w of equals() n hashCode()

> One returns an integer that represents the hash code

> of the object being queried, the other compares a

> supplied object to the object being queried.

>

> They're implemented in whatever way the class in

> question had them implemented

public class Ex

{

public static void main(String[] s)

{

Ex2 aa = new Ex2();

aa.a = 10;

ExA ab = new ExA();

aa.test();

ab.test();

ab.a = 20;

//ab = aa;

// ab = new Ex2();

System.err.println("aa hashCode: " + aa.hashCode());

System.err.println("ab hashCode: " + ab.hashCode());

if(aa.equals(ab))

{

System.out.println("Both aa & ab r equal...");

}

if(aa.hashCode() == ab.hashCode())

{

System.err.println("Both aa.hashCode() & ab.hashCode() aresame");

}

}

here i ve 3 classes Ex, Ex2, ExA. Ex2 extends ExA.

in these two classes somewhere i ve corresponding variables and methods that are used.

Now if I execute, both the if blocks wont work.

but if I uncomment the 1st comment, then both if blocks executes.

then wer comes the difference b/w equals() and hashCode()in the implementation...

Shaik_Sajana at 2007-7-12 11:50:14 >

> Uncommenting the first commented line makes ab hold

> the same exact object as aa. So of course it

> evaluates both if statements to be true. They are

> the same object.

yes boss, i understood that they both hold the same mem loc of the object.

but what am not getting s;

1) the diff b/w these two methods.

2) where comes the difference?

Shaik_Sajana at 2007-7-12 11:50:14 >

> hashCode

>

> method return integer supposed to identify for every

> object ,

Not really. "Identify" makes it sound like each object's hashcode will be unique, when clearly it won't be. In fact return 42; is a perfectly legal hashCode implementation.

jverda at 2007-7-12 11:50:14 >