Synchronization

• Many times, different threads need to access the same data or variable.
• A race condition results if multiple threads corrupt a variable.
• To ensure that this does not happen, you must synchronize the data or methods that are called.
• The Bank Account example in the book (pg 44-45) demonstrates this well.
• To synchronize an entire method, we simply add the synchronize keyword to that method's signature.
• Example:  public void transfer(int amount) { becomes  public synchronized void transfer(int amount) {
• Why not just synchronize everything?
• Synchronization is expensive.  It requires more processing and slows down the program, so we should only use it when we need it.
• Methods that simply return constants definitely do not need to be synchronized.  Only methods that contain atomic transactions.

Created by:  Brandan Jones December 17, 2001