is it possible to define execution order for a set of threads in java

Question

My understanding is that threads in theory are executed in parallel. JVM decides; when a resource is available which thread to pick from the waiting thread queue (based on some

Answer 1

You can set order for your threads.

I've tried to modelling your situation:

public class ThreadJoinExample {
    private static final Thread FIRST = new Thread( new RunnableImpl(), "first" );
    private static final Thread SECOND = new Thread( new RunnableImpl(), "second" );
    public static void main(String[] args) {
        //here have started current thread or "main" thread that will control above threads
        FIRST.start();
        //waiting 2 seconds, "stop" your current thread and after current thread will start this "t3" thread until it will dead
        try {
            FIRST.join(2000);
        } catch (InterruptedException e) {
            System.out.println();
            e.printStackTrace();
        }
        SECOND.start();
        //"stop" your current thread immediately and run "t1" thread until it will dead.
        try {
            SECOND.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //Or we can wait for all threads and in the end - finish current main thread
        try {
            FIRST.join();
            SECOND.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Current thread is going die");
    }
}
class RunnableImpl implements Runnable{

    @Override
    public void run() {
        System.out.println("Started thread: "+Thread.currentThread().getName());
        try {
            Thread.sleep(4000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Thread is going die: "+Thread.currentThread().getName());
    }
}

---

Output:

Started thread: first
Started thread: second
Thread is going die: first
Thread is going die: second
Current thread is going die

summary: With .join() method we can move current thread to Runnable state until the time when "joined thread" will dead