import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

public class Solution {

    private int start = 1;

    /**

     * 对flag的写入虽然加锁保证了线程安全，但由于读取时不是volatile所以可能会读到旧值

     */

    private volatile boolean flag = false;

    /**

     * 重入锁

     */

    private final static Lock LOCK = new ReentrantLock();

    public static void main(String[] args) {

        long startTime = System.currentTimeMillis();

        Solution s = new Solution();

        Thread t1 = new Thread(new OuNum(s));

        t1.setName("t1");

        Thread t2 = new Thread(new JiNum(s));

        t2.setName("t2");

        t1.start();

        t2.start();

        long endTime = System.currentTimeMillis();    //获取结束时间

        System.out.println("程序运行时间：" + (endTime - startTime) + "ms");    //输出程序运行时间

    }

    public static class OuNum implements Runnable {

        private Solution number;

        public OuNum(Solution number) {

            this.number = number;

        }

        @Override

        public void run() {

            while(number.start <= 100) {

                if(number.flag) {

                    try {

                        LOCK.lock();

                        System.out.println("偶数" + "+-+" + number.start);

                        number.start++;

                        number.flag = false;

                    }finally {

                        LOCK.unlock();

                    }

                }

            }

        }

    }

    public static class JiNum implements Runnable {

        private Solution number;

        public JiNum(Solution number) {

            this.number = number;

        }

        @Override

        public void run() {

            while(number.start < 100) {

                if(!number.flag) {

                    try {

                        LOCK.lock();

                        System.out.println("奇数" + "+-+" + number.start);

                        number.start++;

                        number.flag = true;

                    }finally {

                        LOCK.unlock();

                    }

                }

            }

        }

    }

}