java 两个线程交替打印1-100输出到控制台

java 两个线程交替打印1-100输出到控制台：
package com.thread;
public class TestThread {
    public static void main(String[] args) {
        test();
    }
    static long sum=0l;
    Boolean falg=false;
    public static void test() {
        PrintNum printNum = new PrintNum();
        System.out.println("開始進入th1線程--");
        Thread th1=new Thread(new Runnable() {
            @Override
            public void run() {
                while(true) {
                    try {
                        printNum.printO();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
//                    System.out.println("sum:"+sum);
                }}
        });
        th1.start();

        System.out.println("開始進入th2線程--");
        Thread th2=new Thread(new Runnable() {
            @Override
            public void run() {
                while(true) {
                    try {
                        sum= printNum.printJ();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    if(sum==100) {
                        break;
                    }
                }
            }});
        th2.start();
    }
}
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package com.thread;

public class PrintNum {

    private long num=0l;
    //打印奇数
    public  synchronized  long printJ() throws InterruptedException {
        //当num 是偶数时 ，线程等待
        while(num % 2==0) {
         try {
            this.wait();
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
        }
        System.out.println("打印奇数");
        System.out.println(Thread.currentThread().getName()+" :"+ num);
        num++;
        this.notify();
        return num;
    }
    //打印偶数
    public synchronized void printO() throws InterruptedException {
        //当num 是奇数时 ，线程等待
        while(num % 2==1) {
         try {
            this.wait();
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
        }
        System.out.println("打印偶数");
        System.out.println(Thread.currentThread().getName()+" :"+ num);
        num++;
        this.notify();
    }
}