让线程按指定顺序执行

忘是亡心i 2023-06-23 06:53 30阅读 0赞

### 文章目录 ###

*   *  使用线程的join方法
     *  使用主线程的join
     *  利用单线程池
     *  CountDownLatch
     *  CyclicBarrier

## 使用线程的join方法 ##

public class ThreadJoinDemo { 
    
        public static void main(String[] args) { 
            final Thread thread1 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("1");
                }
            });
    
            final Thread thread2 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        thread1.join();
                        System.out.println("2");
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            Thread thread3 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        thread2.join();
                        System.out.println("3");
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            thread2.start();
            thread3.start();
            thread1.start();
        }
    }

## 使用主线程的join ##

public class ThreadJoinDemo2 { 
    
        public static void main(String[] args) throws InterruptedException { 
            final Thread thread1 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("1");
                }
            });
    
            final Thread thread2 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("2");
                }
            });
    
            Thread thread3 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("3");
                }
            });
    
            thread1.start();
            thread1.join();
            thread2.start();
            thread2.join();
            thread3.start();
        }
    }

## 利用单线程池 ##

public class ThreadPoolDemo { 
    
        static ExecutorService executorService = Executors.newCachedThreadPool();
    
        public static void main(String[] args) throws Exception { 
    
            final Thread thread1 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("1");
                }
            });
    
            final Thread thread2 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("2");
                }
            });
    
            Thread thread3 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("3");
                }
            });
    
            executorService.submit(thread1);
            executorService.submit(thread2);
            executorService.submit(thread3);
            executorService.shutdown();
        }
    }

## CountDownLatch ##

public class ThreadCountDownLatchDemo { 
    
        /** * 用于判断线程一是否执行，倒计时设置为1，执行后减1 */
        private static CountDownLatch c1 = new CountDownLatch(1);
    
        /** * 用于判断线程二是否执行，倒计时设置为1，执行后减1 */
        private static CountDownLatch c2 = new CountDownLatch(1);
    
        public static void main(String[] args) { 
            final Thread thread1 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    System.out.println("1");
                    //对c1倒计时-1
                    c1.countDown();
                }
            });
    
            final Thread thread2 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        //等待c1倒计时，计时为0则往下运行
                        c1.await();
                        System.out.println("2");
                        //对c2倒计时-1
                        c2.countDown();
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            Thread thread3 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        //等待c2倒计时，计时为0则往下运行
                        c2.await();
                        System.out.println("3");
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            thread3.start();
            thread1.start();
            thread2.start();
        }
    }

## CyclicBarrier ##

public class CyclicBarrierDemo { 
    
        static CyclicBarrier barrier1 = new CyclicBarrier(2);
        static CyclicBarrier barrier2 = new CyclicBarrier(2);
    
        public static void main(String[] args) { 
    
            final Thread thread1 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        System.out.println("1");
                        //放开栅栏1
                        barrier1.await();
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            final Thread thread2 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        //放开栅栏1
                        barrier1.await();
                        System.out.println("2");
                        //放开栅栏2
                        barrier2.await();
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            final Thread thread3 = new Thread(new Runnable() { 
                @Override
                public void run() { 
                    try { 
                        //放开栅栏2
                        barrier2.await();
                        System.out.println("3");
                    } catch (InterruptedException e) { 
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) { 
                        e.printStackTrace();
                    }
                }
            });
    
            thread3.start();
            thread1.start();
            thread2.start();
        }
    }

https://mp.weixin.qq.com/s/tc5HLyTxAKE3t6CpKFdk5A（线程间是如何通信的？）