Override method "equals" doesn't work over 99 id

Question

I found this code to use ArrayList.contains with java object:

@Override
public boolean equals(Object object)
{
    boolean equals = false;

    if (object != null && object instanceof User)
    {
        equals= this.getId() == ((User) object).getId();
    }

    return equals;
}

Until objects with id 99, this method work fine, but over 99 it returns ever false, can someone help me?

if(users.contains(user)){return true;}

possible duplicate of [Why Integer class caching values in the range -128 to 127?](http://stackoverflow.com/questions/20897020/why-integer-class-caching-values-in-the-range-128-to-127) — user902383, Jul 06 '15 at 09:39
Not sure why it is working to 99, it should work to 127, and it is related to integer caching — user902383, Jul 06 '15 at 09:42
Can you show a runnable example (including the failing call to `ArrayList.contains`) that reproduces the problem? Your equals implementation doesn't seem to be the problem here. — Chronio, Jul 06 '15 at 09:44

score 3 · Accepted Answer · answered Jul 06 '15 at 09:47

3

Java uses caching of numbers for non-primitive types. So until some value (127 for Integer) you'll have same object for numbers.

Change your '==' to equals() to make it work.

answered Jul 06 '15 at 09:47

Stan

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Override method "equals" doesn't work over 99 id

1 Answers1