Increment a Integer's int value?

William_62122 0
Viewed 254024

How do I increment a Integer's value in Java? I know I can get the value with intValue, and I can set it with new Integer(int i).

playerID.intValue()++;

does not seem to work.

Note: PlayerID is a Integer that has been created with:

Integer playerID = new Integer(1);
integer int class java
9 Answers

Java 7 and 8. Increment DOES change the reference, so it references to another Integer object. Look:

@Test
public void incInteger()
{
    Integer i = 5;
    Integer iOrig = i;
    ++i; // Same as i = i + 1;
    Assert.assertEquals(6, i.intValue());
    Assert.assertNotEquals(iOrig, i);
}

Integer by itself is still immutable.

user_16601270

All the primitive wrapper objects are immutable.

I'm maybe late to the question but I want to add and clarify that when you do playerID++, what really happens is something like this:

playerID = Integer.valueOf( playerID.intValue() + 1);

Integer.valueOf(int) will always cache values in the range -128 to 127, inclusive, and may cache other values outside of this range.

user_79686730
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