三个线程交替打印ABC（Condition实现精确通知）

三个线程交替打印ABC：

package pc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class C {
    
    
    public static void main(String[] args) {
    
    
        Data3 data3 = new Data3();
        new Thread(()->{
    
    
            for (int i = 0; i < 50; i++) {
    
    
                data3.PrintA();
            }
        }).start();
        new Thread(()->{
    
    
            for (int i = 0; i < 50; i++) {
    
    
                data3.PrintB();
            }
        }).start();
        new Thread(()->{
    
    
            for (int i = 0; i < 50; i++) {
    
    
                data3.PrintC();
            }
        }).start();
    }
}
class Data3{
    
    
    private char chars = 'A';
    Lock lock = new ReentrantLock();
    Condition condition1 = lock.newCondition();
    Condition condition2 = lock.newCondition();
    Condition condition3 = lock.newCondition();

    public void PrintA(){
    
    
        lock.lock();
        try {
    
    
            while (chars != 'A') {
    
    
                //等待
                condition1.await();
            }
            System.out.print(chars);
            chars = 'B';
            condition2.signal();
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }finally {
    
    
            lock.unlock();
        }
    }

    public void PrintB(){
    
    
        lock.lock();
        try {
    
    
            while (chars != 'B') {
    
    
                condition2.await();
            }
            System.out.print(chars);
            chars = 'C';
            condition3.signal();
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            lock.unlock();
        }
    }
    public void PrintC() {
    
    
        lock.lock();
        try {
    
    
            while (chars != 'C') {
    
    
                condition3.await();
            }
            System.out.print(chars);
            chars = 'A';
            condition1.signal();
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            lock.unlock();
        }
    }
}

---

生产者和消费者问题：

（synchronize + wait + notifyAll）

//判断等待，业务，通知
class Data {
    
    
    private int number = 0;

    public synchronized void increment() throws InterruptedException {
    
    
        while (number != 0) {
    
    
            //等待
            this.wait();
        }
        number++;
        System.out.println(Thread.currentThread().getName() + "=>" + number);
        //通知其他线程，我+1完毕了
        this.notifyAll();
    }

    public synchronized void decrement() throws InterruptedException {
    
    
        while (number == 0) {
    
    
            this.wait();
        }
        number--;
        System.out.println(Thread.currentThread().getName() + "=>" + number);
        //通知其他线程，我-1完毕了
        this.notifyAll();
    }
}

（ReentrantLock+Condition）

package pc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class B {
    
    
    public static void main(String[] args) {
    
    
        Data2 data = new Data2();
        new Thread(() -> {
    
    
            for (int i = 0; i < 10; i++) {
    
    
                try {
    
    
                    data.increment();
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
        }, "A").start();
        new Thread(() -> {
    
    
            for (int i = 0; i < 10; i++) {
    
    
                try {
    
    
                    data.decrement();
                } catch (InterruptedException e) {
    
    
                    e.printStackTrace();
                }
            }
        }, "B").start();
    }
}

class Data2 {
    
    
    private int number = 0;
    Lock lock = new ReentrantLock();
    Condition condition = lock.newCondition();

    public void increment() throws InterruptedException {
    
    
        lock.lock();
        try {
    
    
            while (number != 0) {
    
    
                //等待
                condition.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我+1完毕了
            condition.signalAll();
        } catch (Exception e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            lock.unlock();
        }
    }

    public void decrement() throws InterruptedException {
    
    
        lock.lock();
        try {
    
    
            while (number == 0) {
    
    
                condition.await();
            }
            number--;
            System.out.println(Thread.currentThread().getName() + "=>" + number);
            //通知其他线程，我-1完毕了
            condition.signalAll();
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        } finally {
    
    
            lock.unlock();
        }
    }
}