I hope this will not be considered as a misuse of the java-dev
mailing list. The issue I am reporting is probably not relevant for
most developers but I came across it and I was very surprised.
Imagine creating an ArrayList of Integers
ArrayList<Integer> list = new ArrayList<Integer>();
and adding elements to it. You can do this is two ways (at least):
1) you may have some primitive of type int and you may add that
directly to your ArrayList
list.add(myPrimitiveInt);
2) or you can create the Integer object from the primitive
list.add(new Integer(myPrimitiveInt));
Now imagine to do the following:
int myPrimitiveInt = 4;
ArrayList<Integer> list = new ArrayList<Integer>();
list.add(myPrimitiveInt);
list.add(myPrimitiveInt);
What really surprises me is that now you will get true from the
condition (list.get(0) == list.get(1)) !
This is really unexpected as the method ArrayList.get(int) returns
an Integer object not a primitive and the == operator should check
if the two objects are the same and not if their value is the same.
In fact if you do the following:
int myPrimitiveInt = 4;
ArrayList<Integer> list = new ArrayList<Integer>();
list.add(new Integer(myPrimitiveInt));
list.add(new Integer(myPrimitiveInt));
the condition (list.get(0) == list.get(1)) will return false as expected.
I checked with several other JVMs on different platform and none of
them gave this weird result (i.e. all of them gave false in both
cases).
Has anybody else come across this before? Do Apple has a place where
you can post bugs of this type? Is there some obvious thing I am
missing?
Many thanks. Cheers,
Francesca
