String.intern() Method

[Chinmay Kant]

Code:-
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public class Test21{
public static void main(String a[]){
String s1 = new String("Hai");
String s2 = "Hai";
String s3 = new String("Hai").intern();
System.out.println(s1 == s2);
System.out.println(s1 == s3);
System.out.println(s2 == s3);
}
}
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The Answer is false false true

SO, why Answer cannot be false true false.

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Here are the details of intern method from javadocs:-

public String intern()
Returns a canonical representation for the string object.

A pool of strings, initially empty, is maintained privately by the class String.

When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(Object) method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.

It follows that for any two strings s and t, s.intern() == t.intern() is true if and only if s.equals(t) is true.

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[Sagar Rohankar]

hi

In java , == operator when applied to reference , then it checks for
'refernce ' equality( Each refernce in java has a hash code value) and not for 'value' contained by that reference. To check whether two string contain same value , use equal() method.

hope this answer a lil bit to you.

regardz;

Sagar

[Sandip Kaviman]

It is because of new String("Hai"); When you use new keyword object is created in nonpool memory.

Thanks
Sandip