Java Thread allow lock on variable?

Question

I have a situation where i have more then 20 threads each has some variable call it- int [ ] variable.
Now each thread wants to see this variable of all other thread and any thread is allowed to add value of int array of any other thread.
Now suppose a reference to int array or all threads is availabe to all other threads, is there a way to put a lock on it?
So say Thread 1 is changing int array of Thread 2. Can thread 1 put a lock on thread 2's int array so while it is changing the value of that int array no one else can do anything to it?
At the same time if some other thread is accessing the int array of thread 2, thread1 is put on hold until it gets it's turn to put lock on it?
Thx!!!

Answer 1

Now suppose a reference to int array or all threads
is availabe to all other threads, is there a way to
put a lock on it? Look at the "synchronized" keyword.
So say Thread 1 is changing int array of Thread 2.Typically variables aren't associated with threads but rather with other objects.
You can have thread local variables, but the point of that is to preclude this kind of thing.
Read this:
http://java.sun.com/docs/books/tutorial/essential/concurrency/