一、介绍

• 与继承Thread类和实现Runnable接口两种创建线程方式的区别
  ① Callable接口可以有返回值
  ② Callable接口可以抛出异常
  ③ 执行方法不同，call()方法和run()方法

二、代码演示

• 继承Thread类和实现Runnable接口的方式创建线程

  package callable;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * @author swaggyhang
   * @create 2023-07-04 19:41
   */
  public class Test01 {
      public static void main(String[] args) {
          // 1. 继承Thread类
          for (int i = 1; i <= 10; i++) {
              MyThread myThread = new MyThread();
              myThread.setName(String.valueOf(i));
              myThread.start();
          }
  
          try {
              TimeUnit.SECONDS.sleep(3);
          } catch (InterruptedException e) {
              e.printStackTrace();
          }
  
          // 2. 实现Runnable接口
          for (int i = 1; i <= 10; i++) {
              Thread thread = new Thread(new MyThread1());
              thread.setName(String.valueOf(i));
              thread.start();
          }
      }
  }
  
  class MyThread extends Thread {
      @Override
      public void run() {
          System.out.println(Thread.currentThread().getName());
      }
  }
  
  class MyThread1 implements Runnable {
      @Override
      public void run() {
          System.out.println(Thread.currentThread().getName());
      }
  }
  

• Callable接口的方式创建线程

  package callable;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.FutureTask;
  
  /**
   * @author swaggyhang
   * @create 2023-07-04 20:12
   */
  public class Test02 {
      public static void main(String[] args) throws ExecutionException, InterruptedException {
          for (int i = 1; i <= 10; i++) {
              // FutureTask是Runnable接口的一个实现类
              // FutureTask构造器接收Callable参数
              FutureTask<String> futureTask = new FutureTask<>(new MyThread3());
              new Thread(futureTask, String.valueOf(i)).start();
              // futureTask.get()方法可能会产生阻塞，一般是放在程序最后
              // 或者使用异步通信来处理！
              System.out.println(futureTask.get());
          }
      }
  }
  
  class MyThread3 implements Callable<String> {
  
      @Override
      public String call() throws Exception {
          return "call():" + Thread.currentThread().getName();
      }
  }
  

• Callable接口的返回结果是有缓存的，两个线程同时调用，会获取同一个返回值

• Callable接口的返回结果可能需要等待，会出现阻塞