Is there any performance issue in making Array List thread using Collections. synchronized List?

all methods of synchronized list use synchronization which will work slower than direct accesss.

java.util.Vector is an implementation of List which already has all methods synchronized

Synchronization itself almost does not affect performance since java 1.4. However applications that are designed with a lot of synchronization blocks can run slowly because different threads are waiting each other.

There are other approaches that help us to design multi threaded applications without or with minimal synchronization.

1. use stateless architecture
2. use immutable objects
3. think about actors model

yeah, you incur the overhead of threads being blocked...

If you read your list more than you write to it, java.util.concurrent.CopyOnWriteArrayList is an option for you. Reads will be fast with no locking.

You can use this approach as you are getting immutable list instance so no worry for multiple threads acccessing it. List immutablelist = Collections.unmodifiableList(list);

The problem with Collections.synchronizedList((List<T> list)) is that: in many cases, it is not really useful. For exmple, for iterating over all elements, or when getting a value, do computations based on it, and replace it with the result, we have to use manual synchronization anyway.

Fromt the documentation of Collections.synchronizedList((List<T> list))

It is imperative that the user manually synchronize on the returned list when iterating over it:

  List list = Collections.synchronizedList(new ArrayList());
      ...
  synchronized (list) {
      Iterator i = list.iterator(); // Must be in synchronized block
      while (i.hasNext())
          foo(i.next());
  }

Failure to follow this advice may result in non-deterministic behavior.