• Thread should be seen as deprecated

Java introduces the Executor Framework as a new Highlevel Mechanism to handle concurrency.

Basically this includes the following steps:

• Create a Worker classes that either implements Runnable or Callable
• Create Worker instances
• Create an ExecutorService
  • newSingleThreadExecutor
  • newCachedThreadPool
  • newFixedThreadPool
• Submit the workers to the executor service
• Wait for the workers to finish
• Shutdown the ExecutorService

public class ThreadPoolExecutorDemo {
 
	public static void main(String[] args) throws Exception {
		ExecutorService executor = Executors.newFixedThreadPool(2);
 
		executor.submit(new Worker());
		executor.submit(new Worker());
 
		executor.shutdown();
                executor.awaitTermination(60, TimeUnit.SECONDS); // wait until finished, but at most for 60 seconds
 
		System.out.println("Done");
	}
 
	public static class Worker implements Runnable {
		@Override
		public void run() {
		        // do work
		}
	}
}

If the Worker should yield a result, implement Callable<T> instead of Runnable:

public class ThreadPoolTest {
	public static void main(String[] args) throws Exception {
		ExecutorService executor = Executors.newFixedThreadPool(2);
 
		Future<Integer> result1 = executor.submit(new Worker());
		Future<Integer> result2 = executor.submit(new Worker());
 
		System.out.println("Results: " + result1.get() + " "  result2.get()); // note that get() might throw an Exception if the worker did not finish normally
	}
 
	public static class Worker implements Callable<Integer> {
		@Override
		public Integer call() {
                        int result=0;
                        // do some work
			return result;
		}
	}
}

public static void main(String[] args) throws Exception {
  List<Worker> tasks = new ArrayList<>();
 
  tasks.add(new Worker());
  tasks.add(new Worker());
 
  ExecutorService executor = Executors.newFixedThreadPool(2);
  List<Future<Integer>> results = executor.invokeAll(tasks); // blocks until all tasks are done
 
  System.out.println("Result1: " + results.get(0).get());
  System.out.println("Result2: " + results.get(1).get());
 
  System.out.println("Done");
 
  executor.shutdown();
}
 
 
public static class Worker implements Callable<Integer> {
.....
}