public void addShutdownHook(Thread hook) {
  SecurityManager sm = System.getSecurityManager();
  if (sm != null) {
   sm.checkPermission(new RuntimePermission("shutdownHooks"));
  }
  ApplicationShutdownHooks.add(hook);
 }

public boolean removeShutdownHook(Thread hook) {
  SecurityManager sm = System.getSecurityManager();
  if (sm != null) {
   sm.checkPermission(new RuntimePermission("shutdownHooks"));
  }
  return ApplicationShutdownHooks.remove(hook);
 }

private static IdentityHashMap<Thread, Thread> hooks;

  static synchronized void add(Thread hook) {
    if(hooks == null)
      throw new IllegalStateException("Shutdown in progress");

    if (hook.isAlive())
      throw new IllegalArgumentException("Hook already running");

    if (hooks.containsKey(hook))
      throw new IllegalArgumentException("Hook previously registered");

    hooks.put(hook, hook);
  }


  static synchronized boolean remove(Thread hook) {
    if(hooks == null)
      throw new IllegalStateException("Shutdown in progress");

    if (hook == null)
      throw new NullPointerException();

    return hooks.remove(hook) != null;
  }

  static void runHooks() {
    Collection<Thread> threads;
    synchronized(ApplicationShutdownHooks.class) {
      threads = hooks.keySet();
      hooks = null;
    }

    for (Thread hook : threads) {
      hook.start();
    }
    for (Thread hook : threads) {
      try {
        hook.join();
      } catch (InterruptedException x) { }
    }
  }

Shutdown.add(1 , false ,
        new Runnable() {
          public void run() {
            runHooks();
          }
        }
      );

private static final int RUNNING = 0;
private static final int HOOKS = 1;
private static final int FINALIZERS = 2;

private static final int MAX_SYSTEM_HOOKS = 10;
private static final Runnable[] hooks = new Runnable[MAX_SYSTEM_HOOKS];

static void add(int slot, boolean registerShutdownInProgress, Runnable hook) {
    synchronized (lock) {
      if (hooks[slot] != null)
        throw new InternalError("Shutdown hook at slot " + slot + " already registered");

      if (!registerShutdownInProgress) {
        if (state > RUNNING)
          throw new IllegalStateException("Shutdown in progress");
      } else {
        if (state > HOOKS || (state == HOOKS && slot <= currentRunningHook))
          throw new IllegalStateException("Shutdown in progress");
      }

      hooks[slot] = hook;
    }
  }

private static void sequence() {
    synchronized (lock) {
      if (state != HOOKS) return;
    }
    runHooks();
    boolean rfoe;
    synchronized (lock) {
      state = FINALIZERS;
      rfoe = runFinalizersOnExit;
    }
    if (rfoe) runAllFinalizers();
  }

private static void runHooks() {
    for (int i=0; i < MAX_SYSTEM_HOOKS; i++) {
      try {
        Runnable hook;
        synchronized (lock) {
          currentRunningHook = i;
          hook = hooks[i];
        }
        if (hook != null) hook.run();
      } catch(Throwable t) {
        if (t instanceof ThreadDeath) {
          ThreadDeath td = (ThreadDeath)t;
          throw td;
        }
      }
    }
  }