Why does == return true for a String comparison?

Question

I have previously asked a question about comparing 2 strings and was told that I should always use .equals.

However, I do not understand why this then works:

 String y= "Mary";
 String x= "Mary";
 System.out.print(x==y);

This will print true, and I do not understand why.

Because `y` and `x` are both pointing to the same object in the *String constant pool*. — TheLostMind, Sep 22 '14 at 16:11
*"It's an implementation detail of the compiler and the JVM"* - Actually, it is required by the Java specification. It is NOT just an implementation detail. — Stephen C, Sep 22 '14 at 16:12
A bit more detail on the string pool http://stackoverflow.com/questions/2486191/java-string-pool — Chris K, Sep 22 '14 at 16:20

score 3 · Answer 1 · answered Sep 22 '14 at 16:11

Because those two String(s) have the same reference identity, and that is because they came from the String intern pool. If you were to add a new String() to one of them, like so -

String y= "Mary";
String x= new String("Mary");
System.out.print(x==y);

You would get false.

Why does == return true for a String comparison?

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