Why == does not work for Wrapper classes in Java

Question

Why Integer class return false even if value two Integer variables are same. This happens only when value is more than 127.

    Integer a = 300;
    Integer b = 300;
    System.out.println(a==b);

The above code prints false. The value of variables a and b are same then why this prints false.

    Integer a = 127;
    Integer b = 127;
    System.out.println(a==b);

This code will print true. Can anybody please explain me why java behave like this.

Thanks

http://stackoverflow.com/a/3637974/1638708 – User42 Aug 26 '15 at 12:42 — User42, Aug 26 '15 at 12:42

score 3 · Answer 1 · answered Aug 26 '15 at 12:40

3

That's because the values under 127 being cached and using same location of storage for performance reasons in micro level. That's the reason for true in second case.

answered Aug 26 '15 at 12:40

Suresh Atta

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Why == does not work for Wrapper classes in Java

1 Answers1