DelayedTaskRunner

DelayedTaskRunner.java

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Timer;


/**
 * Runs the last surviving task published after a specified delay. 
 *
 * @author STaylor
 */
public class DelayedTaskRunner {
    private final Timer timer;
    private Runnable task;
    
    /**
     * <p>
     * Create a delayed task runner that runs the last task published
     * that survives the duration of the specified delay.
     * </p>
     * <p>
     * This class should be instantiated only from the Event Dispatch
     * Thread.
     * </p>
     *
     * @param delayMs The delay in milliseconds.
     * @throws IllegalArgumentException if {@code delayMs < 0}.
     */
    public DelayedTaskRunner(final int delayMs) throws IllegalArgumentException {
        if (delayMs < 0) {
            throw new IllegalArgumentException("delayMs < 0");
        }
        timer = new Timer(delayMs, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (task != null) {
                    task.run();
                }
                timer.stop();
            }
        });
    }
    
    /**
     * <p>
     * Set the task to be run and reset the timer so that the task
     * will run after the configured delay if not overwritten by
     * another task before the delay expires.
     * </p>
     * <p>
     * Call this method from the Event Dispatch Thread. The specified
     * task, if executed, will be executed in the Event Dispatch Thread.
     * </p> 
     *
     * @param task The task to potentially run.
     */
    public void setTask(final Runnable task) {
        this.task = task;
        timer.restart();
    }
}