java中第三種啟動執行緒的方式是實現Callable介面

package com.lyzx.juc;

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;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;

public class CallableTest {
	public static void main(String[] args) throws InterruptedException, ExecutionException {
		testCallableStart2();
	}
	
	/**
	 * @throws ExecutionException 
	 * @throws InterruptedException 
	 * 
	 */
	public static void testCallableStart2() throws InterruptedException, ExecutionException{
      int itemCount =2000;
      int[] arr = new int[itemCount];
      for(int i=0;i<itemCount;i++){
          arr[i]=i;
      }
      
      Object o = new Object();
		AddArray xx1 = new AddArray(arr,1,1001,o);

		FutureTask<Integer> ft = new FutureTask<Integer>(xx1);
		new Thread(ft).start();
		System.out.println(ft.get());
	}
	
	
	/**
	 * 實現Callable介面後啟動執行緒的兩種方式之執行緒池的方式啟動
	 * @throws InterruptedException
	 * @throws ExecutionException
	 */
	public static void testCallableStart1() throws InterruptedException, ExecutionException{
	       int itemCount =2000;
	        int[] arr = new int[itemCount];
	        for(int i=0;i<itemCount;i++){
	            arr[i]=i;
	        }
	        
	        Object o = new Object();
			AddArray xx1 = new AddArray(arr,1,1001,o);
			AddArray xx2 = new AddArray(arr,1001,2000,o);
			ExecutorService pool = Executors.newFixedThreadPool(3);
			Future<Integer> f1 = pool.submit(xx1);
			Future<Integer> f2 = pool.submit(xx2);
			
			pool.shutdown();
			System.out.println(f1.get()+f2.get());
	}
}


class AddArray implements Callable<Integer>{
	private int[] arr;
	private int start;
	private int end;
	private Object lock;
	
	public AddArray(int[] arr,int start,int end,Object lock){
		this.arr = arr;
		this.start = start;
		this.end = end;
		this.lock = lock;
	}
	
	@Override
	public Integer call() throws Exception {
		int result = 0;
		for(int i=start;i<end;i++){
			result += arr[i];
			TimeUnit.MICROSECONDS.sleep(20);
		}
		return result;
	}
}