public class TestRunnable implements Runnable {
  private String name;

  public TestRunnable(String name) {
    this.name = name;
  }

  @Override
  public void run() {
    while (true) {
      if (Main.Surplus < 0)
        return;
      Main.Surplus--;
      System.out.println(name + " " + Main.Surplus);
    }
  }
}

public static void main(String[] args) {

     TestRunnable runnable = new TestRunnable("runnable1");
     TestRunnable runnable2 = new TestRunnable("runnable2");

     Thread t1 = new Thread(runnable);
     Thread t2 = new Thread(runnable2);

     t1.start();
     t2.start();

  }

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 Main {
  public static int Surplus = 10;

  private ExecutorService executor = Executors.newSingleThreadExecutor();

  void addTask(Runnable runnable) {
    executor.execute(runnable);
  }

  <V> V addTask(Callable<V> callable) {
    Future<V> submit = executor.submit(callable);
    try {
      return submit.get();
    } catch (InterruptedException e) {
      System.out.println("InterruptedException" + e.toString());
    } catch (ExecutionException e) {
      System.out.println("ExecutionException" + e.toString());
    }
    return null;
  }

  public void testAddTask(String name) {
    addTask(new Runnable() {
      @Override
      public void run() {
        for (int i = 0; i < 3; i++) {
          if (Main.Surplus <= 0)
            return;
          Main.Surplus--;
          System.out.println(name + " " + Main.Surplus);
        }

      }
    });
  }

  public void testAddTask2(String name) {
    int count = addTask(new Callable<Integer>() {
      @Override
      public Integer call() throws Exception {
        for (int i = 0; i < 3; i++) {
          if (Main.Surplus <= 0)
            return 0;
          Main.Surplus--;
          System.out.println(name + " " + Main.Surplus);
        }
        return Main.Surplus;
      }
    });

  }

  public void close() {
    executor.shutdown();
  }

  public static void main(String[] args) {
    Main main = new Main();
    main.testAddTask("task1");
    main.testAddTask2("task2");
    main.testAddTask("task3");
    main.testAddTask2("task4");
    main.close();
  }
}