Question

Possible Duplicate:
Wrapper class and == operator

Hi when I am comparing Integer with == I have some problem so
can you explain me why second test is success too ?

@Test
public void integerTest() {
    Integer prvni = 127;
    Integer druhy = 127;
    Integer treti = 128;
    Integer ctvrty = 128;

    assertTrue(prvni == druhy);
    assertTrue(treti != ctvrty);

}

Answer 1

When using == to compare Objects, you’re actually comparing the references. I.e., the reason both assertions are true is because the prvni and druhy refer to the same object while treti and ctvrty does not.

This is because the JVM caches Integer objects in the range -128 to 127, and reuses cached objects when autoboxing the values.

Unless you switch to int instead, you could go through prvni.intValue() or use prvni.equals(...) instead.