多个线程顺序执行

Love The Way You Lie 2022-04-25 00:36 290阅读 0赞

## 1.wait-notifyAll ##

同步方法

package com.study.demo;
    
    /**
     * Created by Administrator on 2019\3\2 0002.
     */
    public class Test {
        private int seq = 1;
    
        public synchronized void method1() {
            try {
                while (seq != 1) {
                    wait();
                }
                System.out.println(Thread.currentThread().getName() + " method1 run");
                seq = 2;
                notifyAll();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
        public synchronized void method2() {
            try {
                while (seq != 2) {
                    wait();
                }
                System.out.println(Thread.currentThread().getName() + " method2 run");
                seq = 3;
                notifyAll();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
        public synchronized void method3() {
            try {
                while (seq != 3) {
                    wait();
                }
                System.out.println(Thread.currentThread().getName() + " method3 run");
                seq = 4;
                notifyAll();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
        public static void main(String[] args) {
            Test test = new Test();
            new Thread1(test).start();
            new Thread2(test).start();
            new Thread3(test).start();
        }
    
    }
    
    class Thread1 extends Thread {
        private Test test;
    
        public Thread1(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method1();
        }
    }
    
    class Thread2 extends Thread {
        private Test test;
    
        public Thread2(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method2();
        }
    }
    
    class Thread3 extends Thread {
        private Test test;
    
        public Thread3(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method3();
        }
    }

method1 run  
method2 run  
method3 run

同步代码块

package com.study.demo;
    
    /**
     * Created by Administrator on 2019\3\2 0002.
     */
    public class Test {
        private int seq = 1;
        private final Object lock = new Object();
    
        public void method1() {
            synchronized (lock) {
                try {
                    while (seq != 1) {
                        lock.wait();
                    }
                    System.out.println(Thread.currentThread().getName() + " method1 run");
                    seq = 2;
                    lock.notifyAll();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
        public void method2() {
            synchronized (lock) {
                try {
                    while (seq != 2) {
                        lock.wait();
                    }
                    System.out.println(Thread.currentThread().getName() + " method2 run");
                    seq = 3;
                    lock.notifyAll();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
        public void method3() {
            synchronized (lock) {
                try {
                    while (seq != 3) {
                        lock.wait();
                    }
                    System.out.println(Thread.currentThread().getName() + " method3 run");
                    seq = 4;
                    lock.notifyAll();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
        public static void main(String[] args) {
            Test test = new Test();
            new Thread1(test).start();
            new Thread2(test).start();
            new Thread3(test).start();
        }
    
    }
    
    class Thread1 extends Thread {
        private Test test;
    
        public Thread1(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method1();
        }
    }
    
    class Thread2 extends Thread {
        private Test test;
    
        public Thread2(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method2();
        }
    }
    
    class Thread3 extends Thread {
        private Test test;
    
        public Thread3(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method3();
        }
    }

## 2.await-signal ##

package com.study.demo;
    
    import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.ReentrantLock;
    
    /**
     * Created by Administrator on 2019\3\2 0002.
     */
    public class Test {
        private int seq = 1;
        private final ReentrantLock lock = new ReentrantLock();
        private final Condition condition1 = lock.newCondition();
        private final Condition condition2 = lock.newCondition();
        private final Condition condition3 = lock.newCondition();
    
        public void method1() {
            lock.lock();
            try {
                while (seq != 1) {
                    condition1.await();
                }
                System.out.println(Thread.currentThread().getName() + " method1 run");
                seq = 2;
                condition2.signal();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
            }
        }
    
        public void method2() {
            lock.lock();
            try {
                while (seq != 2) {
                    condition1.await();
                }
                System.out.println(Thread.currentThread().getName() + " method2 run");
                seq = 3;
                condition3.signal();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
            }
        }
    
        public void method3() {
            lock.lock();
            try {
                while (seq != 3) {
                    condition3.await();
                }
                System.out.println(Thread.currentThread().getName() + " method3 run");
                seq = 4;
                condition1.signal();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
            }
        }
    
        public static void main(String[] args) {
            Test test = new Test();
            new Thread1(test).start();
            new Thread2(test).start();
            new Thread3(test).start();
        }
    
    }
    
    class Thread1 extends Thread {
        private Test test;
    
        public Thread1(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method1();
        }
    }
    
    class Thread2 extends Thread {
        private Test test;
    
        public Thread2(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method2();
        }
    }
    
    class Thread3 extends Thread {
        private Test test;
    
        public Thread3(Test test) {
            this.test = test;
        }
    
        @Override
        public void run() {
            test.method3();
        }
    }

## 3.join方法 ##

package com.study.demo;
    
    /**
     * Created by Administrator on 2019\3\2 0002.
     */
    public class Test {
    
        public static void main(String[] args) throws InterruptedException {
            Thread1 thread1 = new Thread1();
            thread1.start();
            thread1.join();
    
            Thread1 thread2 = new Thread1();
            thread2.start();
            thread2.join();
    
            Thread1 thread3 = new Thread1();
            thread3.start();
            thread3.join();
    
        }
    
    }
    
    class Thread1 extends Thread {
        @Override
        public void run() {
            System.out.println(Thread.currentThread().getName() + " run");
        }
    }

Thread-0 run  
Thread-1 run  
Thread-2 run

## 4.Semaphore信号量 ##

package com.study.demo;
    
    import java.util.concurrent.Semaphore;
    
    /**
     * Created by Administrator on 2019\3\2 0002.
     */
    public class Test {
    
        private static Semaphore A = new Semaphore(1);
        private static Semaphore B = new Semaphore(1);
        private static Semaphore C = new Semaphore(1);
    
        public static void main(String[] args) {
            ThreadA a = new ThreadA();
            ThreadB b = new ThreadB();
            ThreadC c = new ThreadC();
    
            try {
                B.acquire();
                C.acquire();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            a.start();
            b.start();
            c.start();
        }
    
        static class ThreadA extends Thread {
            @Override
            public void run() {
                try {
                    A.acquire();
                    System.out.println("thread a run");
                    B.release();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
        static class ThreadB extends Thread {
            @Override
            public void run() {
                try {
                    B.acquire();
                    System.out.println("thread b run");
                    C.release();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    
        static class ThreadC extends Thread {
            @Override
            public void run() {
                try {
                    C.acquire();
                    System.out.println("thread c run");
                    A.release();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }

thread a run  
thread b run  
thread c run  
A，B，C三个信号量，主线程B，C都获取凭证了，所以b，c两个线程只能阻塞，而a线程可以拿到凭证，所以a线程执行了  
然后B信号量释放，所以b线程可以执行，接着c线程