How to use TimerTask with lambdas?

While Marko's answer is perfectly correct, I prefer my implementation:

public class FunctionalTimerTask extends TimerTask {

    Runnable task;

    public FunctionalTimerTask(Runnable task) {
        this.task = task;
    }

    @Override
    public void run() {
        task.run();
    }
}

 public static class Task {
    public static TimerTask set(Runnable run) {
        return new FunctionalTimerTask(() -> System.err.println("task"));
    }
}

 Timer timer = new Timer(false);
 timer.schedule(Task.set(() -> doStuff()), TimeUnit.SECONDS.toMillis(1));

This gives you more control over the timer, and you have a static utility class. Idealy give it a name that won't conflict with other common thread class, so not Task, Job, Timer.

To complete Marko Topolnik's answer about Timer, you just have to call schedule method with a lambda.

schedule(() -> {
    System.out.println("Task #1 is running");
}, 500);

Noting first that Timer is effectively an antiquated API, but entertaining your question nevertheless, you could write a small wrapper around it which would adapt the schedule method to accept a Runnable, and on the inside you'd turn that Runnable into a TimerTask. Then you would have your schedule method which would accept a lambda.

public class MyTimer {
  private final Timer t = new Timer();

  public TimerTask schedule(final Runnable r, long delay) {
     final TimerTask task = new TimerTask() { public void run() { r.run(); }};
     t.schedule(task, delay);
     return task;
  }
}