init, thx MrExtremez

2006Redone Server/src/redone/event/Task.java

@@ -0,0 +1,180 @@
+package redone.event;
+
+/**
+ * Represents a periodic task that can be scheduled with a {@link TaskScheduler}
+ * .
+ * 
+ * @author Graham
+ */
+public abstract class Task {
+
+	/**
+	 * The number of cycles between consecutive executions of this task.
+	 */
+	private final int delay;
+
+	/**
+	 * A flag which indicates if this task should be executed once immediately.
+	 */
+	private final boolean immediate;
+
+	/**
+	 * The current 'count down' value. When this reaches zero the task will be
+	 * executed.
+	 */
+	private int countdown;
+
+	/**
+	 * A flag which indicates if this task is still running.
+	 */
+	private boolean running = true;
+
+	/**
+	 * Creates a new task with a delay of 1 cycle.
+	 */
+	public Task() {
+		this(1);
+	}
+
+	/**
+	 * Creates a new task with a delay of 1 cycle and immediate flag.
+	 * 
+	 * @param immediate
+	 *            A flag that indicates if for the first execution there should
+	 *            be no delay.
+	 */
+	public Task(boolean immediate) {
+		this(1, immediate);
+	}
+
+	/**
+	 * Creates a new task with the specified delay.
+	 * 
+	 * @param delay
+	 *            The number of cycles between consecutive executions of this
+	 *            task.
+	 * @throws IllegalArgumentException
+	 *             if the {@code delay} is not positive.
+	 */
+	public Task(int delay) {
+		this(delay, false);
+	}
+
+	/**
+	 * Creates a new task with the specified delay and immediate flag.
+	 * 
+	 * @param delay
+	 *            The number of cycles between consecutive executions of this
+	 *            task.
+	 * @param immediate
+	 *            A flag which indicates if for the first execution there should
+	 *            be no delay.
+	 * @throws IllegalArgumentException
+	 *             if the {@code delay} is not positive.
+	 */
+	public Task(int delay, boolean immediate) {
+		checkDelay(delay);
+		this.delay = delay;
+		countdown = delay;
+		this.immediate = immediate;
+	}
+
+	/**
+	 * Checks if this task is an immediate task.
+	 * 
+	 * @return {@code true} if so, {@code false} if not.
+	 */
+	public boolean isImmediate() {
+		return immediate;
+	}
+
+	/**
+	 * Checks if the task is running.
+	 * 
+	 * @return {@code true} if so, {@code false} if not.
+	 */
+	public boolean isRunning() {
+		return running;
+	}
+
+	/**
+	 * Checks if the task is stopped.
+	 * 
+	 * @return {@code true} if so, {@code false} if not.
+	 */
+	public boolean isStopped() {
+		return !running;
+	}
+
+	/**
+	 * This method should be called by the scheduling class every cycle. It
+	 * updates the {@link #countdown} and calls the {@link #execute()} method if
+	 * necessary.
+	 * 
+	 * @return A flag indicating if the task is running.
+	 */
+	public boolean tick() {
+		if (running && --countdown == 0) {
+			execute();
+			countdown = delay;
+		}
+		return running;
+	}
+
+	/**
+	 * Performs this task's action.
+	 */
+	protected abstract void execute();
+
+	/**
+	 * Changes the delay of this task.
+	 * 
+	 * @param delay
+	 *            The number of cycles between consecutive executions of this
+	 *            task.
+	 * @throws IllegalArgumentException
+	 *             if the {@code delay} is not positive.
+	 */
+	public void setDelay(int delay) {
+		checkDelay(delay);
+		delay = 0;
+	}
+
+	/**
+	 * Stops this task.
+	 * 
+	 * @throws IllegalStateException
+	 *             if the task has already been stopped.
+	 */
+	public void stop() {
+		checkStopped();
+		running = false;
+	}
+
+	/**
+	 * Checks if the delay is negative and throws an exception if so.
+	 * 
+	 * @param delay
+	 *            The delay.
+	 * @throws IllegalArgumentException
+	 *             if the delay is not positive.
+	 */
+	private void checkDelay(int delay) {
+		if (delay <= 0) {
+			throw new IllegalArgumentException("Delay must be positive.");
+		}
+	}
+
+	/**
+	 * Checks if this task has been stopped and throws an exception if so.
+	 * 
+	 * @throws IllegalStateException
+	 *             if the task has been stopped.
+	 */
+	private void checkStopped() {
+		if (!running) {
+			throw new IllegalStateException();
+		}
+	}
+
+}