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Threads

• Defined by either extending java.lang.Thread or by implementing java.lang.Runnable interface. The run() method needs to be overridden. This method must be public and void and should take no arguments.

• Extending
  class MyThread extends Thread {
  public void run() {/* ... */}
  }
  You never call run() directly. Instead you call the start() method of the Thread class.
  MyThread my = new MyThread();
  mt.start();

• Implementing
  class MyRunnable implements Runnable {
  public void run() {/* ... */}
  }
  Here you construct a thread by passing the instance of the Runnable class as an argument.
  MyRunnable mc = new MyRunnable();
  Thread t = new Thread(mc);
  t.start();

• Thread Constructors available

  • Thread()

  • Thread(String name)

  • Thread(Runnable runnable)

  • Thread(Runnable runnable, String name)

  • Thread(ThreadGroup g, Runnable runnable)

  • Thread(ThreadGroup g, Runnable runnable, String name)

  • Thread(ThreadGroup g, String name)

• wait(), notify and notifyAll() have to be called from a synchronized context.

• A dead thread can never enter any other state, even if the start() method is called on it.

• yield() method causes the current thread to move from the running to the runnable state to give other threads a chance to run.

• When a thread calls join() on another thread, the currently running thread will wait until the thread it joins with has completed.

• The argument to a synchronized keyword (in the case of blocks) is the reference of the object to be synchronized on. In the case of methods, the synchronized keyword merely precedes the method.

• Invoking start() twice on the same thread will throw an IllegalThreadStateException at runtime.