Android: Incrementing an integer causes an allocation

Question

The following line appears in the allocations pane of eclipse:

Alloc Order       Allocation Size           Allocated Class
509               12                        java.lang.Integer

It references this line of java code:

MyInteger++;

I changed it around a little bit, but it still causes an allocation.

MyInteger=MyInteger+1;
MyInteger=MyInteger+MyIntegerIncrementor;

Why do these lines of code cause an allocation?

for the purposes of this question it is Integer, whether using int or Integer is better depends on the context of your problem. In general you are right and int should be used. — tjb, May 15 '12 at 15:47

score 3 · Accepted Answer · answered May 15 '12 at 15:30

3

Since Integer is immutable, each time you increment it a new object is created, hence the allocation.

answered May 15 '12 at 15:30

Amokrane Chentir

Is there any easy way to tell whether an Object is immutable? – tjb May 15 '12 at 15:48
1

@tjb Google/Documentation. This article lists immutable Objects http://www.javaranch.com/journal/2003/04/immutable.htm for instance. – Amokrane Chentir May 15 '12 at 15:51
@tbj You might be interested in this question: http://stackoverflow.com/questions/203475/how-do-i-identify-immutable-objects-in-java – Amokrane Chentir May 15 '12 at 16:00

1 Answers1