public class BoundedExecutor {     private final Executor exec;     private final Semaphore semaphore;     public BoundedExecutor(Executor exec, int bound) {            this. exec = exec;            this. semaphore = new Semaphore(bound);     }     public void submitTask( final Runnable command) throws InterruptedException {            semaphore.acquire();            try {                 exec. execute(new Runnable() {                      public void run() {                            try {                                command.run();                           } finally {                                 semaphore.release();                           }                     }                });           } catch (RejectedExecutionException e) {                 semaphore.release();           }     }}