二十、并发编程之Condition的使用

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三个线程按顺序循环执行

• 使用线程之间的通信wait、notify写代码

public class Demo {
	private int signal;
	public synchronized void a() {
		while(signal != 0 ) {//signal等于0打印a
			try {
				wait();//等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("a");
		signal ++;//signal加1
		notifyAll();//唤醒
	}
	
	public synchronized void b() {
		while(signal != 1) {//signal等于1打印b
			try {
				wait();//等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("b");
		signal ++;//signal加1
		notifyAll();//唤醒
	}
	
	public synchronized void c () {
		while(signal != 2) {//signal等于2打印c
			try {
				wait();//等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("c");
		signal = 0;//signal设置为0
		notifyAll();//唤醒
	}
	
	public static void main(String[] args) {
		Demo d = new Demo();
		A a = new A(d);
		B b = new B(d);
		C c = new C(d);
		new Thread(a).start();
		new Thread(b).start();
		new Thread(c).start();
		
	}
}

class A implements Runnable {
	private Demo demo;
	public A(Demo demo) {
		this.demo = demo;
	}

	@Override
	public void run() {
		while(true) {
			demo.a();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	
}
class B implements Runnable {
	private Demo demo;
	public B(Demo demo) {
		this.demo = demo;
	}
	
	@Override
	public void run() {
		while(true) {
			demo.b();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	
}
class C implements Runnable {
	private Demo demo;
	public C(Demo demo) {
		this.demo = demo;
	}
	
	@Override
	public void run() {
		while(true) {
			demo.c();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

• 使用Condition写代码

public class Demo {
	private int signal;
	Lock lock = new ReentrantLock();
	Condition a = lock.newCondition();
	Condition b = lock.newCondition();
	Condition c = lock.newCondition();
	
	public void a() {
		lock.lock();//加锁
		while(signal != 0 ) {//signal等于0打印a
			try {
				a.await();//a等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("a");
		signal ++;//signal加1
		b.signal();//唤醒b
		lock.unlock();// 释放锁
	}
	
	public void b() {
		lock.lock();//加锁
		while(signal != 1) {//signal等于1打印b
			try {
				b.await();//b等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("b");
		signal ++;//signal加1
		c.signal();//唤醒c
		lock.unlock();// 释放锁
	}
	
	public synchronized void c () {
		lock.lock();//加锁
		while(signal != 2) {//signal等于2打印c
			try {
				c.await();//c等待
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		System.out.println("c");
		signal = 0;//signal设置为0
		a.signal();//唤醒a
		lock.unlock();// 释放锁
	}
	
	public static void main(String[] args) {
		Demo d = new Demo();
		A a = new A(d);
		B b = new B(d);
		C c = new C(d);
		new Thread(a).start();
		new Thread(b).start();
		new Thread(c).start();
		
	}
}

class A implements Runnable {
	private Demo demo;
	public A(Demo demo) {
		this.demo = demo;
	}

	@Override
	public void run() {
		while(true) {
			demo.a();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	
}
class B implements Runnable {
	private Demo demo;
	public B(Demo demo) {
		this.demo = demo;
	}
	
	@Override
	public void run() {
		while(true) {
			demo.b();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
	
}
class C implements Runnable {
	private Demo demo;
	public C(Demo demo) {
		this.demo = demo;
	}
	
	@Override
	public void run() {
		while(true) {
			demo.c();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}