UNable to find out difference

[srinibash udayasingh]

Hi Ranchers

i unable to distinguish why all the out put is "hello".
This is example from kathy siera book

Integer x=10;
Integer y=10;
if(x==y)
System.out.println("hello");

if(x!=y)
System.out.println("hello");

if(x.equals(y))
System.out.println("hello");

[Murali Kakarla]

Page 236 of K&B book have the explanation for this.
Here is part of it for your reference:

...
two instances of the
following wrapper objects will always be == when their primitive values are the same:
* Boolean
* Byte
* Character from \u0000 to \u007f (7f is 127 in decimal)
* Short and Integer from -128 to 127
...

[srinibash udayasingh]

Hi
Thanks for the reply.

But my question if Integer wraper class reference hold same value then then == returns true.Then why != also gives true.

[Kishore Kumar]

Hi sri,
Are you sure that == returns true and != returns true.
I tried the following

  class Test 
{
public static void main(String[] args) 
{
Integer x=10;
Integer y=10;
if(x==y)
System.out.println("hello");
 
if(x!=y)
System.out.println("hello1");
}
}
  

Only hello is displayed. Run the program once and check.
[ March 12, 2008: Message edited by: kesava narayana ]

[Irina Goble]

Srinibash, it might help if you compile it with println statements like these:

        System.out.println("x == y " + (x == y));
        System.out.println("x != y " + (x != y));
        System.out.println("x.equals(y) " + x.equals(y));