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Thread: Address of String instance

  1. #1
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    Default Address of String instance

    AClass c=new AClass(“Hi”);
    System.out.print(c);// here it prints the address of  object c
    String s=new String(“Hi”);
    System.out.print(s);// here it prints Hi. But I need the address of s.

    Can anyone help give the code to find address of s ?
    Last edited by helloworld922; September 5th, 2010 at 11:48 PM.

  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Address of String instance

    In both cases it's actually calling the toString() method. The default toString method for objects is to append the class name followed by the hashCode (default is the memory address).

    For obvious reasons, the String toString() method returns itself. However, the String class also overrides the hashCode() method so there's no easy way to retrieve the memory address of the string (I don't think it's possible without using JNI).

    The larger question is why would you want to know the memory address of strings? In Java, you can't manually modify this value, except by setting it to a "valid" object of that type or null.

  3. #3
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    Default Re: Address of String instance

    I wanted to know the address for the reason that :
    String s1=new String("Hi");
    String s2=new String("Hi");
    System.out.print(s1==s2);// false
    System.out.print(s1==s2);// true
    I understand why it's false in the first case. If it's true in the second then what is true (is it the address?)
    what is there at the addresses of s1 and s2 ?
    Last edited by helloworld922; September 6th, 2010 at 03:27 PM.

  4. #4
    Administrator copeg's Avatar
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    Default Re: Address of String instance

    For object equality, you should be using the equals as opposed to equality with '==', which is more for primitives. Using your example:
    String s1 = new String("HI");
    String s2 = new String("HI");
    For custom objects, you can override the Object.equals method to accomplish this task. In the case of String, you could also call intern() on your strings, which causes the String to be stored/recalled from memory, in which case the == will return true.
    Last edited by copeg; September 6th, 2010 at 02:24 PM.

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