Why aren't Integers cached in Java?

Question

I know there are similar posts on the topic, but they don\'t quite address my question. When you do:

Integer a = 10;
Integer b = 10;
System.out.println(\"a =         


        

Answer 1

Assuming your describing the behavior of you code accurately it sounds like autoboxing isn't working on the 'gets' (=) operatior, instead it sounds like Integer x = 10; gives the object x a memory pointer of '10' instead of a vale of 10. Therefore ((a == b) == true)( will evaluate to true because == on objects operates on the memory addresses which you assigned both to 10.

So when should you use autoboxing and unboxing? Use them only when there is an “impedance mismatch” between reference types and primitives, for example, when you have to put numerical values into a collection. It is not appropriate to use autoboxing and unboxing for scientific computing, or other performance-sensitive numerical code. An Integer is not a substitute for an int; autoboxing and unboxing blur the distinction between primitive types and reference types, but they do not eliminate it.

What oracle has to say on the subject.

Notice that the documentation doesn't supply any examples with the '=' operator.