Can I use Callable threads without ExecutorService?

Question

Can I use Callable threads without ExecutorService? We can use instances of Runnable and subclasses of Thread without ExecutorService and this code works normally. But this code

Answer 1

import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;

public class MainClass {
    public static void main(String[] args) {
        try {
            Callable c = () -> {
                System.out.println(Thread.currentThread().getName());
                return "true";
            };
            FutureTask ft = new FutureTask(c);
            Thread t = new Thread(ft);
            t.start();

            String result = ft.get();
            System.out.println(result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
/*
   Output: 
   Thread-0 
   true
 */