What are the Big-O Complexities of Java Collection Framework Implementations?

Big-O Complexity for Java Collections Framework Implementations

In Java programming, understanding the Big-O complexity of different collection implementations is crucial for optimized code performance. For teaching purposes or personal reference, having a comprehensive summary of these complexities can be invaluable.

List Implementations

• ArrayList: Fast get and add operations (O(1)), but contains, next, and remove operations can be slower (O(n)).
• LinkedList: Slow get operations (O(n)), but faster add and remove operations (O(1)).
• CopyOnWriteArrayList: Slow add (O(n)) but constant time for concurrent operations.

Set Implementations

• HashSet: Constant time for add and contains (O(1)), but iterating is slower (O(h/n)).
• LinkedHashSet: Fast add, contains, and iteration (O(1)).
• TreeSet: Logarithmic time complexity for add and contains (O(log n)).

Map Implementations

• HashMap: Constant time for get and containsKey (O(1)), but iteration is slower (O(h/n)).
• LinkedHashMap: Similar to HashMap, but preserves insertion order.
• TreeMap: Logarithmic time complexity for get, containsKey, and iteration (O(log n)).

Queue Implementations

• PriorityQueue: Logarithmic time complexity for offer and poll (O(log n)).
• ConcurrentLinkedQueue: Fast concurrent operations (O(1)).
• ArrayBlockingQueue: Constant time for offer, peek, poll, and size (O(1)).
• LinkedBlockingQueue: Similar to ArrayBlockingQueue, but supports blocking operations.

Additional Resources

The following resources provide further in-depth information:

• Java Generics and Collections (book)
• Collections Overview (official Java documentation)
• Annotated Outline (official Java documentation)

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