Java (1 != 1) is true

Question

I have an if statement in my code as follows:

if (key != a[0]) /* line to be executed */

When I run my program with key = 1 (type Integer) and a[0] = 1 (type Integer), I get a true and the statement runs, i.e. 1 does not equal 1. Obviously, this is absurd.

I've done a lot of testing on this, and I can't find a value of key that will give me a false for key != a[0]. a[0] can't change, for the purposes of my program.

What's wrong?

Try: https://stackoverflow.com/questions/7520432/what-is-the-difference-between-vs-equals-in-java — vanza, Jan 04 '18 at 05:53
Every wrapper class types must be compared using the `equals` method only. — VPK, Jan 04 '18 at 05:55
Thanks! My apologies that I couldn't find the answer by myself. — nschmeller, Jan 04 '18 at 06:01

score 3 · Accepted Answer · edited Jan 04 '18 at 06:10

3

.equals() method checks for equality, == operator checks for object sameness. As long as key and a[0] are not the same Object, == will return false. .equals() on an Integer will return true.

edited Jan 04 '18 at 06:10

VPK

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answered Jan 04 '18 at 05:55

Jeff Wang

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Adding to the answer, `==` does not check for sameness. It checks for the object references. If both operands refer to the same object, it will return true. – VPK Jan 04 '18 at 06:12

Java (1 != 1) is true

1 Answers1