Main difference between wait and sleep is that wait() method release the acquired monitor when thread is waiting while Thread.sleep() method keeps the lock or monitor even if thread is waiting. Also wait method in java should be called from synchronized method or block while there is no such requirement for sleep() method. Another difference is Thread.sleep() method is a static method and applies on current thread, while wait() is an instance specific method and only got wake up if some other thread calls notify method on same object. also in case of sleep, sleeping thread immediately goes to Runnable state after waking up while in case of wait, waiting thread first acquires the lock and then goes into Runnable state. So based upon your need if you require a specified second of pause use sleep() method or if you want to implement inter-thread communication use wait method.

here is list of difference between wait and sleep in Java :

1) wait is called from synchronized context only while sleep can be called without synchronized block. see Why wait and notify needs to call from synchronized method for more detail.

2) wait is called on Object while sleep is called on Thread. see Why wait and notify are defined in object class instead of Thread.

3) waiting thread can be awake by calling notify and notifyAll while sleeping thread can not be awaken by calling notify method.

4) wait is normally done on condition, Thread wait until a condition is true while sleep is just to put your thread on sleep.

5) wait release lock on object while waiting while sleep doesnâ??t release lock while waiting.

Difference between yield and sleep in java

Major difference between yield and sleep in Java is that yield() method pauses the currently executing thread temporarily for giving a chance to the remaining waiting threads of the same priority to execute. If there is no waiting thread or all the waiting threads have a lower priority then the same thread will continue its execution. The yielded thread when it will get the chance for execution is decided by the thread scheduler whose behavior is vendor dependent. Yield method doesnâ??t guarantee that current thread will pause or stop but it guarantee that CPU will be relinquish by current Thread as a result of call to Thread.yield() method in java.

Sleep method in Java has two variants one which takes millisecond as sleeping time while other which takes both mill and nano second for sleeping duration.

sleep(long millis) or sleep(long millis,int nanos)

Cause the currently executing thread to sleep for the specified number of milliseconds plus the specified number of nanoseconds.