Comparing 2 Integer values are giving different output

Question

Possible Duplicate:
Java question about autoboxing and object equality / identity

Integer i1 = 10;
Integer i2 = 10;
Integer i3 = 210;
Integer i4 = 210;

if(i1 ==i2){
      System.out.println("True");
}else{
      System.out.println("False");
}
if(i3==i4){
       System.out.println("True");
}else{
       System.out.println("False");
}
if(Integer.valueOf(10) ==Integer.valueOf(10)){
       System.out.println("True");
}else{
      System.out.println("False");
}
if(Integer.valueOf(210) ==Integer.valueOf(210)){
       System.out.println("True");
}else{
       System.out.println("False");
}

The answer is

True

False

True

False

Why it is giving false for 2 and 4 condition ?

You can see the solution here: http://stackoverflow.com/questions/10223555/java-comparison-not-working-when-integer-larger-than-128 — Averroes, Jul 13 '12 at 11:49
Actually http://stackoverflow.com/questions/5117132/integer-wrapper-objects-share-the-same-instances-only-within-the-value-127 is probably the better close target. — Joachim Sauer, Jul 13 '12 at 11:50
In JDK1.5 there is a new concept called Caching Integer Objects. In JDK1.5 the JVM caches Integer objects from range of -128 to 127 . So every time an integer object is create with value between the above mentioned range same object will be returned instead of creating the new object. — Rahul Agrawal, Jul 13 '12 at 12:32

score 5 · Answer 1 · answered Jul 13 '12 at 11:51

5

Use .equals() to compares Integer.== compares refrences equality

answered Jul 13 '12 at 11:51

Samir Mangroliya

39,918
16
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score 3 · Answer 2 · answered Jul 13 '12 at 11:50

3

== compares instances not values. Use int instead of Integer and it will work

answered Jul 13 '12 at 11:50

juergen d

201,996
37
293
362

score 2 · Accepted Answer · answered Jul 13 '12 at 11:50

2

Note that Integer is an object, not a primitive. You're comparing different object instances.

For this particular example, it's worth reading about boxing.

answered Jul 13 '12 at 11:50

Brian Agnew

268,207
37
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440

score 1 · Answer 4 · answered Jul 13 '12 at 11:50

1

In Java use the Object function Object.equals(Object) to compare objects. That comparison would only work correctly using the primitive int.

answered Jul 13 '12 at 11:50

Nuno

1,163
1
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15

Comparing 2 Integer values are giving different output

4 Answers4