public class TestThreadPool {
 
 //定长线程池，每当提交一个任务就创建一个线程，直到达到线程池的最大数量，这时线程数量不再变化，当线程发生错误结束时，线程池会补充一个新的线程
 static ExecutorService fixedExecutor = Executors.newFixedThreadPool(3);
 
 
 public static void main(String[] args) {
  testFixedExecutor();
 }
 
 //测试定长线程池，线程池的容量为3，提交6个任务，根据打印结果可以看出先执行前3个任务，3个任务结束后再执行后面的任务
 private static void testFixedExecutor() {
  for (int i = 0; i < 6; i++) {
   final int index = i;
   fixedExecutor.execute(new Runnable() {
    public void run() {
     try {
      Thread.sleep(3000);
     } catch (InterruptedException e) {
      e.printStackTrace();
     }
     System.out.println(Thread.currentThread().getName() + " index:" + index);
    }
   });
  }
  
  try {
   Thread.sleep(4000);
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
  System.out.println("4秒后...");
  
  fixedExecutor.shutdown();
 }
 
}

public class TestThreadPool {
 
 //可缓存的线程池，如果线程池的容量超过了任务数，自动回收空闲线程，任务增加时可以自动添加新线程，线程池的容量不限制
 static ExecutorService cachedExecutor = Executors.newCachedThreadPool();
 
 
 public static void main(String[] args) {
  testCachedExecutor();
 }
 
 //测试可缓存线程池
 private static void testCachedExecutor() {
  for (int i = 0; i < 6; i++) {
   final int index = i;
   cachedExecutor.execute(new Runnable() {
    public void run() {
     try {
      Thread.sleep(3000);
     } catch (InterruptedException e) {
      e.printStackTrace();
     }
     System.out.println(Thread.currentThread().getName() + " index:" + index);
    }
   });
  }
  
  try {
   Thread.sleep(4000);
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
  System.out.println("4秒后...");
  
  cachedExecutor.shutdown();
 }
 
}