Java: Integer equals vs. ==

The JVM is caching Integer values. Hence the comparison with == only works for numbers between -128 and 127.

Refer: #Immutable_Objects_.2F_Wrapper_Class_Caching

You can't compare two Integer with a simple == they're objects so most of the time references won't be the same.

There is a trick, with Integer between -128 and 127, references will be the same as autoboxing uses Integer.valueOf() which caches small integers.

If the value p being boxed is true, false, a byte, a char in the range \u0000 to \u007f, or an int or short number between -128 and 127, then let r1 and r2 be the results of any two boxing conversions of p. It is always the case that r1 == r2.

Resources :

• JLS - Boxing

On the same topic :

• autoboxing vs manual boxing java

Integer refers to the reference, that is, when comparing references you're comparing if they point to the same object, not value. Hence, the issue you're seeing. The reason it works so well with plain int types is that it unboxes the value contained by the Integer.

May I add that if you're doing what you're doing, why have the if statement to begin with?

mismatch = ( cdiCt != null && cdsCt != null && !cdiCt.equals( cdsCt ) );

"==" always compare the memory location or object references of the values. equals method always compare the values. But equals also indirectly uses the "==" operator to compare the values.

Integer uses Integer cache to store the values from -128 to +127. If == operator is used to check for any values between -128 to 127 then it returns true. for other than these values it returns false .

Refer the link for some additional info