Directly accessible data structure Java

The CopyOnWriteArrayList structure could solve your problem (java.util.concurrent).

• CopyOnWriteArrayLists is thread-safe because all mutative operations are implemented by creating a copy of the list.

• The problem of ConcurrentModificationException is avoided because the array doesn’t change while iterated. The so called snapshot style iterator uses a reference to the state of the array when the iterator was created.

• If you have much more reads than writes, use CopyOnWriteArrayList, otherwise use Vector.

• Vector introduces a small synchronization delay for each operation, when CopyOnWriteArrayList has a longer delay for write (due to copying) but no delay for reads.

• Vector requires explicit synchronization when you are iterating it (so write operations can’t be executed at the same time), CopyOnWriteArrayList doesn’t.