两个线程打印 1-n，⼀个线程打印奇数，⼀个线程打印偶数

1. 题目

创建两个线程，打印1~n，一个线程负责打印奇数，一个负责打印偶数。

2. 思路

• 通过 wait() 和 notify() 方法实现两个线程的交替打印
• 定义几个线程共享变量，进行打印方法的控制

3. 代码

public class ThreadPrint {

    static class ParityPrinter{
        // n的值
        private int max;
        // 当前打印值
        private int num=1;
        // 是否打印奇数
        private boolean odd=true;

        public ParityPrinter(int max){
            this.max = max;
        }

        // 打印奇数
        public synchronized void printOdd(){
            while (num < max){
                while(!odd){
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                }
                System.out.println(Thread.currentThread().getName() + " : " + num);
                num++;
                odd = false;
                notify();
            }
        }

        // 打印偶数
        public synchronized void printEven(){
            while (num < max){
                while (odd){
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        throw new RuntimeException(e);
                    }
                }
                System.out.println(Thread.currentThread().getName() + " : " + num);
                num++;
                odd = true;
                notify();
            }
        }
    }

    public static void main(String[] args) {
        ParityPrinter printer = new ParityPrinter(100);
        Thread t1 = new Thread(printer::printOdd, "t1");
        Thread t2 = new Thread(printer::printEven, "t2");
        t1.start();
        t2.start();
    }
}