why code gives true ?

[Vishy Karl]

HI All,
Just experimenting why does the following code output true ??

 
 Object o = "works";
 String s = "workds";
 System.out.println(o == s );
 

Output is true. why ?

[Vad Fogel]

Hi Vishy, would you mind my modifying your code so it does return true?

class RefCompare{
    public static void main(String[] args){
        Object o = "works"; 
        String s = "works"; 
        System.out.println(o == s );        
    }
}

You are creating two references that point to the same object, which is a String literal "works". Line Object o = "works"; declares an Object reference variable o, creates and interns a String "works", and assigns it to o; the line following it declares a String reference s and assigns it to "works" in the String constant pool.
== operator returns true if two references point to the same object on the heap. o==s is valid because String IS-A Object, so instanceof test passes OK. Otherwise, a compile error would've been thrown. Hope this helps.
[ December 07, 2003: Message edited by: Vad Fogel ]

[Mohit Goyal]

well although the Reference types are different, the actual object is the same String in the String pool.
Since == checks only for the 2 references pointing to the same object it returns true in the above case.

[Vishy Karl]

Thanks for your replies