Monday 6 January 2020

Strings in Java : equals vs ==

Answer


Answer






Possible Duplicate:
How do I compare strings in Java? 






  String s1 = "andrei";
  String s2 = "andrei";


  String s3 = s2.toString();

  System.out.println((s1==s2) + " " + (s2==s3));


Giving the following code why is the second comparison s2 == s3 true ?
What is actually s2.toString() returning ? Where is actually located (s2.toString()) ?


Answer



First of all String.toString is a no-op:




/**
 * This object (which is already a string!) is itself returned.
 *
 * @return  the string itself.
 */
public String toString() {
    return this;
}



Second of all, String constants are interned so s1 and s2 are behind the scenes changed to be the same String instance.


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