I can't make an arraylist of integers?!

Newbie & Debugging Questions
#1

I started using arraylists a few weeks ago for my game because it seemed like the thing to do
I love them! I am pretty acquainted with arraylists

Previously I’ve been using them to store entities in a room. I have a problem that I decided is best solved by an arraylist of integers
But this code errors:

private static ArrayList<int> occupiedRowList = new ArrayList<int>();

Looks good to me. What’s wrong with it?

Thanks

#2

You need to have an ArrayList of Integer not int, int is a primitive data type not an object.

#3

Generics in Java have the limitation of only supporting objects, no primitives as Swattkidd7 mentioned.

For primitive types, you have to use their class counterparts and rely on auto-boxing and auto-unboxing magic, for example:


ArrayList<Integer> myList = new ArrayList<Integer>();

myList.add(3); //the compiler automatically turns this into myList.add(Integer.valueOf(3));
int i = myList.get(0); //the compiler automatically turns this into int i = myList.get(0).intValue();

This works the same for all the other primitive types and their class counterparts.

#4

Huh… weird. Well, it does work. Thanks everybody

#5

You might want to use the Apache Commons Collections API:

http://commons.apache.org/collections/
http://commons.apache.org/collections/api/
http://commons.apache.org/primitives/apidocs/org/apache/commons/collections/primitives/IntList.html

#6

I wouldn’t recommend apache collections anymore, it is quite outdated. From Java 2 times?
Take a look at google guava http://code.google.com/p/guava-libraries, which is activly developed and has a lot of more cool features.

#7

I never used them either, but on the other hand, how many bugs can you write in IntList ?