Java – the ordering thread runs in the create / start order

How do I order threads in the order they are instantiated How do I make the following program print numbers 1... 10 in order

public class ThreadOrdering {
    public static void main(String[] args) {

        class MyRunnable implements Runnable{
            private final int threadnumber;

            MyRunnable(int threadnumber){
                this.threadnumber = threadnumber;
            }

            public void run() {
                System.out.println(threadnumber);
            }
        }

        for(int i=1; i<=10; i++){
            new Thread(new MyRunnable(i)).start();
        }
    }
}

Solution

Sounds like the executorservice you want Invokeall, which returns the results of the worker threads in a fixed order, although they can be arranged in any order:

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class ThreadOrdering {

    static int NUM_THREADS = 10;

    public static void main(String[] args) {
        ExecutorService exec = Executors.newFixedThreadPool(NUM_THREADS);
        class MyCallable implements Callable<Integer> {
            private final int threadnumber;

            MyCallable(int threadnumber){
                this.threadnumber = threadnumber;
            }

            public Integer call() {
                System.out.println("Running thread #" + threadnumber);
                return threadnumber;
            }
        }

        List<Callable<Integer>> callables =
            new ArrayList<Callable<Integer>>();
        for(int i=1; i<=NUM_THREADS; i++) {
            callables.add(new MyCallable(i));
        }
        try {
            List<Future<Integer>> results =
                exec.invokeAll(callables);
            for(Future<Integer> result: results) {
                System.out.println("Got result of thread #" + result.get());
            }
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        } catch (ExecutionException ex) {
            ex.printStackTrace();
        } finally {
            exec.shutdownNow();
        }
    }

}