implementing debounce in Java

Question

For some code I\'m writing I could use a nice general implementation of debounce in Java.

public interface Callback {
  public void call(Object          


        

Answer 1

Here is my working implementation:

Execution Callback:

public interface cbDebounce {

void execute();

}

Debouncer:

public class Debouncer {

private Timer timer;
private ConcurrentHashMap delayedTaskMap;

public Debouncer() {
    this.timer = new Timer(true); //run as daemon
    this.delayedTaskMap = new ConcurrentHashMap<>();
}

public void debounce(final String key, final cbDebounce debounceCallback, final long delay) {
    if (key == null || key.isEmpty() || key.trim().length() < 1 || delay < 0) return;

    cancelPreviousTasks(); //if any

    TimerTask timerTask = new TimerTask() {
        @Override
        public void run() {
            debounceCallback.execute();
            cancelPreviousTasks();
            delayedTaskMap.clear();
            if (timer != null) timer.cancel();
        }
    };

    scheduleNewTask(key, timerTask, delay);
}

private void cancelPreviousTasks() {
    if (delayedTaskMap == null) return;

    if (!delayedTaskMap.isEmpty()) delayedTaskMap
            .forEachEntry(1000, entry -> entry.getValue().cancel());

    delayedTaskMap.clear();
}

private void scheduleNewTask(String key, TimerTask timerTask, long delay) {
    if (key == null || key.isEmpty() || key.trim().length() < 1 || timerTask == null || delay < 0) return;

    if (delayedTaskMap.containsKey(key)) return;

    timer.schedule(timerTask, delay);

    delayedTaskMap.put(key, timerTask);
}

}

Main (to test)

public class Main {

private static Debouncer debouncer;

public static void main(String[] args) throws IOException, InterruptedException {
    debouncer = new Debouncer();
    search("H");
    search("HE");
    search("HEL");
    System.out.println("Waiting for user to finish typing");
    Thread.sleep(2000);
    search("HELL");
    search("HELLO");
}

private static void search(String searchPhrase) {
    System.out.println("Search for: " + searchPhrase);
    cbDebounce debounceCallback = () -> System.out.println("Now Executing search for: "+searchPhrase);
    debouncer.debounce(searchPhrase, debounceCallback, 4000); //wait 4 seconds after user's last keystroke
}

}

Output

• Search for: H
• Search for: HE
• Search for: HEL
• Waiting for user to finish typing
• Search for: HELL
• Search for: HELLO
• Now Executing search for: HELLO