This RejectedExecutionHandler implementation discards the rejected Runnable if the ThreadPoolExecutor has been shut down. Otherwise, it discards the oldest pending task that has not run and tries again to execute( ) the rejected task.

public static class ThreadPoolExecutor.DiscardOldestPolicy implements RejectedExecutionHandler {
// Public Constructors
     public DiscardOldestPolicy( );  
// Methods Implementing RejectedExecutionHandler
     public void rejectedExecution(Runnable r, ThreadPoolExecutor e);  
}