Java Thread

To start a Java thread, we need a java.lang.Runnable.

Thread thrNew = new Thread(aRunnable);
thrNew.start();

Interrupting a Thread

public class Dialog implements Runnable {
	@Override
	public void run() {
		Thread thrCur = Thread.currentThread();
		String name = thrCur.getName();
		System.out.printf("%s entering Dialog#run\n", name);
		while (! Thread.interrupted()) {
			System.out.printf("%s looping in Dialog#run\n", name);
		}
		System.out.printf("%s leaving Dialog#run", name);
	}
}

Then we just have to call thread.interrupt() from the main.

Making a Thread Reusable

Once a thread is interrupted, we have to create a new one, we can't start it again. A workaround for this is to make a thread reusable:

public class Dialog { // no longer a Runnable
	Thread thread;
	Runnable runnable = new Runnable() { 
		@Override
		public void run() {
			Thread thrCur = Thread.currentThread();
			String name = thrCur.getName();
			System.out.printf("%s entering Dialog#run\n", name);
			while (!Thread.interrupted()) {
				System.out.printf("%s looping in Dialog#run\n", name);
			}
			System.out.printf("%s leaving Dialog#run", name);
			thread = null;
		}
	};

	public boolean start() {
		if (thread == null) {
			thread = new Thread(runnable);
			thread.start();
			return true;
		}
		return false;
	}

	public void stop() {
		if (thread != null)
			thread.interrupt();
	}
}

Concurrency

To avoid concurrency, we can use the synchronized keyword:

public class Fifo {
	protected Object[] v;
	protected int size;

	public Fifo() {
		v = new Object[100];
		size = 0;
	}

	public void append(Object o) {
		synchronized (this) {
			v[size] = o;
			size++;
		}	}

	public Object get() {
		synchronized (this) {
			if (size == 0)
				return null;
			Object o = v[0];
			size--;
			for (int i = 0; i < size; i++)
				v[i] = v[i + 1];
			v[size] = null;
			return o;
		}
	}
}

META

Status:: #wiki/notes/mature
Plantations:: Java
References:: ILOG