What is the equivalent of javascript setTimeout in Java?

Question

I need to implement a function to run after 60 seconds of clicking a button. Please help, I used the Timer class, but I think that that is not the best way.

Dross

This question has some good relevant answers: https://mcmap.net/q/136291/-how-to-set-a-timer-in-java – Nealson

Answer 1

"I used the Timer class, but I think that that is not the best way."

The other answers assume you are not using Swing for your user interface (button).

If you are using Swing then do not use Thread.sleep() as it will freeze your Swing application.

Instead you should use a javax.swing.Timer.

See the Java tutorial How to Use Swing Timers and Lesson: Concurrency in Swing for more information and examples.

Barozzi

even though this is the accepted answer it is woefully outdated, especially since the advent of java 9. See the answer below about the delayedExecutor – Embrue

Answer 2

Asynchronous implementation with JDK 1.8:

public static void setTimeout(Runnable runnable, int delay){
    new Thread(() -> {
        try {
            Thread.sleep(delay);
            runnable.run();
        }
        catch (Exception e){
            System.err.println(e);
        }
    }).start();
}

To call with lambda expression:

setTimeout(() -> System.out.println("test"), 1000);

Or with method reference:

setTimeout(anInstance::aMethod, 1000);

To deal with the current running thread only use a synchronous version:

public static void setTimeoutSync(Runnable runnable, int delay) {
    try {
        Thread.sleep(delay);
        runnable.run();
    }
    catch (Exception e){
        System.err.println(e);
    }
}

Use this with caution in main thread – it will suspend everything after the call until timeout expires and runnable executes.

Bromine

yeah don't do it this way - it will start too many threads, I think the CompletableFuture technique is better – Bibliomania

CompletableFuture still creates a new Thread. See CompletableFuture.java#2745. – Bromine

huh, is there a way to tell CompletableFuture to use a threadpool instead of creating a new thread each time? or does it already do that? – Bibliomania

Even Java's built-in Timer class starts "too many threads": "A facility for threads to schedule tasks for future execution in a background thread." I think this way is actually pretty clean. It doesn't handle the repeat-execution case, but you could always have your task just call settimeout again at the end. – Carrier

It's not precisely like javascript setTimeout - setTimeout returns id which can be used for cancelation via clearTimeout – Pepys

Answer 3

Use Java 9 CompletableFuture, every simple:

CompletableFuture.delayedExecutor(5, TimeUnit.SECONDS).execute(() -> {
  // Your code here executes after 5 seconds!
});

Humus

Snippet not working it shows the error: The method delayedExecutor(int, TimeUnit) is undefined for the type CompletableFuture – Virgate

I think I made a mistake, it's for Java 9, not Java 8. Use Java 9 and everything is fine. – Humus

for anyone working with java 9 and up this should be the accepted answer – Embrue

Answer 4

Using the java.util.Timer:

new Timer().schedule(new TimerTask() {
    @Override
    public void run() {
        // here goes your code to delay
    }
}, 300L); // 300 is the delay in millis

Here you can find some info and examples.

Mehala

Thanks, I also needed clearTimeout() alternative so usage is ... Timer timer = new Timer(); timer.schedule(...); timer.cancel(); – Bowel

It's still useful in 2023. Thanks! – Brosine

Answer 5

You can simply use Thread.sleep() for this purpose. But if you are working in a multithreaded environment with a user interface, you would want to perform this in the separate thread to avoid the sleep to block the user interface.

try{
    Thread.sleep(60000);
    // Then do something meaningful...
}catch(InterruptedException e){
    e.printStackTrace();
}

Ponytail

Answer 6

Do not use Thread.sleep as it will freeze your main thread, and not simulate setTimeout from JS.

You need to create and start a new background thread to run your code without stoping the execution of the main thread.

One example:

    new Thread() {
        @Override
        public void run() {
            try {
                this.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            
            
            // your code here

        }
    }.start();

Grunberg

Answer 7

public ScheduledExecutorService = ses;
ses.scheduleAtFixedRate(new Runnable() {
    run() {
            //running after specified time
    }
}, 60, TimeUnit.SECONDS);

It runs after 60 seconds from scheduleAtFixedRate. Check the ScheduledExecutorService documentation.

Bricebriceno

Can you share how your solution is better than the others? And please also explain what your solution is doing rather than just pasting a piece of code. – Renoir

the code creatore was not me. its oracle. better than me , their must explain. pleade refer to this link and read doc.docs.oracle.com/javase/7/docs/api/java/util/concurrent/… – Bricebriceno

Answer 8

You should use Thread.sleep() method.

try {

    Thread.sleep(60000);
    callTheFunctionYouWantTo();
} catch(InterruptedException ex) {

}

This will wait for 60,000 milliseconds(60 seconds) and then execute the next statements in your code.

Ardys

Answer 9

There is setTimeout() method in underscore-java library.

Code example:

import com.github.underscore.Underscore;
import java.util.function.Supplier;

public class Main {

    public static void main(String[] args) {
        final Integer[] counter = new Integer[] {0};
        Supplier<Void> incr =
            () -> {
                counter[0]++;
                return null;
            };
        Underscore.setTimeout(incr, 0);
    }
}

The function will be started in 100ms with a new thread.

Jug

It is definitely inappropriate to use any sort of "sleep" (on the main or active thread) to do this sort of thing. (Nor does it call for the use of a thread.) Some sort of timeout, as suggested here, is definitely called-for. Also: in the timeout-handler, be sure that you verify that the condition-of-interest still exists! (Even if you "delete the timeout" when the condition no longer exists, there is still a miniscule timing-hole left that you cannot completely eliminate.) – Dimmick