Need help for Autboxing..

[Sun Craven]

what does the (int) 128 be stored ?
I konw that only int values between -128 and 127 was stored as immutable objects.So i am confused why Integer k11 (= 128)== int k31( = 128) is true..


Thanks
sun junzhen
[ March 14, 2008: Message edited by: sun jiuzhen ]

[ahmed yehia]

When comparing a wrapper with a primitive using == the wrapper is unboxed, thus Integer == int is evaluated as int == int.

This behavior is unlike comparing using equals() which causes the primitive to auto box. Integer.equals(int) is evaluated as Integer.equals(Integer).
[ March 14, 2008: Message edited by: Ahmed Yehia ]

[Jelle Klap]

The Integer wrapper class keeps track of a cache of 256 Integer objects in the range -128 to 127. If thru autoboxing a new Integer object is created for a value within that range, instead of creating a new instance, the reference to the cached instance is returned. Two Integer references can therefor point to the same object, which is why the == comparison succeeds.

Integer a = 100;
Integer b = 100; 
Integer c = new Integer(100);
    
System.out.println(a==b); //Will print true.
System.out.println(a==c); //Will print false.

Edit: Nevermind I completely missed the point of your question.
[ March 14, 2008: Message edited by: Jelle Klap ]

[sara adrem]

 
public class Boxing {
    public static void main(String[] args) {
        Integer i1 = 128;
        Integer i2 = 128;
        if (i1 == i2) {
            System.out.println("i1 == i2");
        }
        
        Integer i3 = 127;
        Integer i4 = 127;
        if (i3 == i4) {
            System.out.println("i3 == i4");
        }
        
    }
}

o/p: i3 == i4

O/P is as expected.

Something wrong with your sample code

[Sun Craven]

Thanks to all
But answer needs still...
-------------------
What does the int value 128 be stored?
----------------------------------------------
Thanks a lot
sun jiuzhen
[ March 14, 2008: Message edited by: sun jiuzhen ]

[ramesh maredu]

http://www.owasp.org/index.php/Java_gotchas

Please follow above link.

[Ben Souther]

"Craven",
Please check your private messages.
-Ben