LockTester.java

package com.cdzlab.locks;

/**
 * @author arsenik
 */
public class LockTester {
    public LockTester() {
    }

    public void test() throws InterruptedException {
        Object a = new Object();
        Object b = new Object();
        Thread t1 = new Thread(new WorkTask(a, b), "1");
        Thread t2 = new Thread(new WorkTask(a, b), "2");
        t1.start();
        t2.start();

        Thread lockGuard = new Thread(new LockGuard(b), "lockGuard");
        lockGuard.start();
    }

    class LockGuard implements Runnable {
        private Object b;

        LockGuard(Object objB) {
            this.b = objB;
        }

        @Override
        public void run() {
            while (true) {
                guardNotify();
            }
        }

        private void guardNotify() {
            try {
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (b) {
                log(Thread.currentThread().getName(), "guard notify");
                b.notify();
            }
        }
    }

    class WorkTask implements Runnable {
        private Object a;
        private Object b;

        WorkTask(Object objA, Object objB) {
            this.a = objA;
            this.b = objB;
        }

        private void callMe(String name) throws InterruptedException {
            synchronized (a) {
                log(name, "a lock");
                log(name, "get information");
                work();
                synchronized (b) {
                    log(name, " b lock");
                    work();
                    b.wait();
                    log(name, " send information");
                }
            }
            log(name, " after UI update");
        }

        private void work() {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void run() {
            try {
                callMe(Thread.currentThread().getName());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    private void log(String name, String str) {
        System.out.println("[" + name + "] " + str);
    }
}