Delay a method on a new thread

Question

I have 2 methods methodA, methodB. They run on different threads. I want methodB to run with a delay of 100 milliseconds after methodA have started, how do I do that?

the code

final ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(3);
executor.schedule(() -> highs(), 100, TimeUnit.MILLISECONDS);
new Thread(() -> highs()).start();
new Thread(() -> deleteRecords()).start();

I noticed that despise this, methodB always runs before methodA.

Answer 1

By having the ThreadPool execute one thread instantly and then schedule one 100ms later, you'll be able to get the effect you are looking for (having 1 thread run methodA and then another thread run methodB 100 milliseconds later). I wrote a small example to test this:

public class Main {

    public static void main (String[] args) {
        ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(3);
        executor.execute(() -> methodA());
        executor.schedule(() -> methodB(), 100, TimeUnit.MILLISECONDS);
    }

    public static void methodA(){
        System.out.println("A: " + System.currentTimeMillis());
    }

    public static void methodB(){
        System.out.println("B: " + System.currentTimeMillis());
    }
}

This program results in this output:

A: 1575782281388
B: 1575782281492