Java equivalent of std::deque

Question

I'm a relatively new Java programmer coming from C++/STL, and am looking for a class with these characteristics (which the C++ std::deque has, as I understand it):

1. O(1) performance for insertion/removal at the beginning/end
2. O(1) performance for lookup by index
3. are growable collections (don't need fixed size bounds)

Is there a Java equivalent to this? I found the Java 1.6 [ArrayDeque] class which has the insert/removal and growable characteristics, but don't seem to have lookup-by-index unless you call toArray() which would not be O(1).

Answer 1

Primitive Collections for Java has an ArrayDeque with a get(int idx) method.

http://sourceforge.net/projects/pcj

I can't vouch for the quality of this project though.

An alternative would be to get the JDK ArrayDeque source and add the get(int idx) method yourself. Should be relatively easy.

EDIT: If you intend to use the deque in a highly multi-threaded manner, I would go the "patch the JDK's ArrayDeque" route. This implementation has been tested thoroughly and is used in the new java.util.concurrent ForkJoin framework.

Answer 2

My default approach would be to hack together my own class, with ArrayList as an underlying implementation (e.g. map my own class's indices to ArrayList indices)... but I hate reinventing the wheel especially when there's a good chance of screwing up...

Answer 3

Interesting... I was just finishing reading Java Generics and Collections and it has a brief discussion of this kind of collection including a link to the Java Specialists' Newsletter which includes a CircularArrayList that might do what I need.

Answer 4

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