Which Java Collection should I use?

java algorithm arraylist collections hashmap

Tim B · Feb 23, 2014 · Viewed 45.3k times · Source

In this question How can I efficiently select a Standard Library container in C++11? is a handy flow chart to use when choosing C++ collections.

I thought that this was a useful resource for people who are not sure which collection they should be using so I tried to find a similar flow chart for Java and was not able to do so.

What resources and "cheat sheets" are available to help people choose the right Collection to use when programming in Java? How do people know what List, Set and Map implementations they should use?

Answer

Since I couldn't find a similar flowchart I decided to make one myself.

This flow chart does not try and cover things like synchronized access, thread safety etc or the legacy collections, but it does cover the 3 standard Sets, 3 standard Maps and 2 standard Lists.

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Other resources

Probably the most useful other reference is the following page from the oracle documentation which describes each Collection.

HashSet vs TreeSet

There is a detailed discussion of when to use HashSet or TreeSet here: Hashset vs Treeset

ArrayList vs LinkedList

Detailed discussion: When to use LinkedList over ArrayList?

Which Java Collection should I use?

Answer

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