Concept of Synchronization in Java

Synchronization in Java is an important concept since Java is a multi-threaded language where multiple threads run in parallel to complete program execution. In multi-threaded environment synchronization of java object or synchronization of java class becomes extremely important. Synchronization in Java is possible by using java keyword "synchronized" and "volatile". Concurrent access of shared objects in Java introduces to kind of errors: thread interference and memory consistency errors and to avoid these errors you need to properly synchronize your java object to allow mutual exclusive access of critical section to two threads.

For more Info:
http://javarevisited.blogspot.in/2011/04/synchronization-in-java-synchronized.html
http://today.java.net/pub/a/today/2004/08/02/sync1.html