线程间交换信息的方式--ReentrantLock重入锁

4.ReentrantLock类的lock()方法与unlock()方法

package edu.hubu.threadexchange;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * created by Sugar  2019/10/11 23:56
 */
public class ReentrantLockDemo {
    public static void main(String[] args) {
        ReentrantLock lock = new ReentrantLock();
        Condition condition = lock.newCondition();

        List<String> list = new ArrayList<>();
        // 实现线程A
        Thread threadA = new Thread(() -> {
            lock.lock();
            for (int i = 1; i <= 10; i++) {
                list.add("abc");
                System.out.println("线程A向list中添加一个元素，此时list中的元素个数为：" + list.size());
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (list.size() == 5)
                    condition.signal();

            }
            lock.unlock();
        });
        // 实现线程B
        Thread threadB = new Thread(() -> {
            lock.lock();
            if (list.size() != 5) {
                try {
                    condition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.println("线程B收到通知，开始执行自己的业务...");
            lock.unlock();
        });
        threadB.start();
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        threadA.start();
    }
}