Question

I may be teaching a ‘Java crash-course’ soon. While it is probably safe to assume that the audience members will know Big-O notation, it is probably not safe to assume that they will know what the order of the various operations on various collection implementations is.

I could take time to generate a summary matrix myself, but if it’s already out there in the public domain somewhere, I’d sure like to reuse it (with proper credit, of course.)

Anyone have any pointers?

Answer 1

The book Java Generics and Collections has this information (pages: 188, 211, 222, 240).

List implementations:

                      get  add  contains next remove(0) iterator.remove ArrayList             O(1) O(1) O(n)     O(1) O(n)      O(n) LinkedList            O(n) O(1) O(n)     O(1) O(1)      O(1) CopyOnWrite-ArrayList O(1) O(n) O(n)     O(1) O(n)      O(n) 

Set implementations:

                      add      contains next     notes HashSet               O(1)     O(1)     O(h/n)   h is the table capacity LinkedHashSet         O(1)     O(1)     O(1)  CopyOnWriteArraySet   O(n)     O(n)     O(1)  EnumSet               O(1)     O(1)     O(1)  TreeSet               O(log n) O(log n) O(log n) ConcurrentSkipListSet O(log n) O(log n) O(1) 

Map implementations:

                      get      containsKey next     Notes HashMap               O(1)     O(1)        O(h/n)   h is the table capacity LinkedHashMap         O(1)     O(1)        O(1)  IdentityHashMap       O(1)     O(1)        O(h/n)   h is the table capacity  EnumMap               O(1)     O(1)        O(1)  TreeMap               O(log n) O(log n)    O(log n)  ConcurrentHashMap     O(1)     O(1)        O(h/n)   h is the table capacity  ConcurrentSkipListMap O(log n) O(log n)    O(1) 

Queue implementations:

                      offer    peek poll     size PriorityQueue         O(log n) O(1) O(log n) O(1) ConcurrentLinkedQueue O(1)     O(1) O(1)     O(n) ArrayBlockingQueue    O(1)     O(1) O(1)     O(1) LinkedBlockingQueue   O(1)     O(1) O(1)     O(1) PriorityBlockingQueue O(log n) O(1) O(log n) O(1) DelayQueue            O(log n) O(1) O(log n) O(1) LinkedList            O(1)     O(1) O(1)     O(1) ArrayDeque            O(1)     O(1) O(1)     O(1) LinkedBlockingDeque   O(1)     O(1) O(1)     O(1) 

The bottom of the javadoc for the java.util package contains some good links:

• Collections Overview has a nice summary table.
• Annotated Outline lists all of the implementations on one page.