Creating new Objects for class Integer

Question

I have a simple java class

public class T {
         public static void main(String[] args) {
                 Integer x = 0;
                 Integer y = 0;
                 Integer a = 255;
                 Integer b = 255;
                 System.out.println( (x==y) );
                 System.out.println( (a==b) );
 }

The console output result is:

true
false

Why is the output for comparing x with y are different from comparing a with b? Why does Java doesn't create objects for small int values?

Because == compares references, not values. Use .equals() for that. — duffymo, Mar 03 '14 at 15:42
why are you using the object Integer rather than the simple primitive int? — La-comadreja, Mar 03 '14 at 15:43
This is a duplicate. Look up "interning" - it's turned on for `Integer`s between -128 and +127. — Sergey Kalinichenko, Mar 03 '14 at 15:44

score 1 · Answer 1 · answered Mar 03 '14 at 15:44

If you want to compare objects in Java use .equals().

public class T {
         public static void main(String[] args) {
                 Integer x = 0;
                 Integer y = 0;
                 Integer a = 255;
                 Integer b = 255;
                 System.out.println( (x.equals(y)) );
                 System.out.println( (a.equals(b)) );
 }

Using == you will just compare the references to both objects, which wont be the same.

Use == only when comparing primitive values.

This however, is not true for Integers from -128 to 127 (including). Here, the `==` comparison will work. — Christoph, Mar 03 '14 at 15:52

Creating new Objects for class Integer

1 Answers1