fix:面试遇到的题:多线程轮询打印

Author: scrazyakai

src/posts/项目/面试遇到的题.md

@@ -134,7 +134,79 @@ public class ShowMeBug {
 ```
 
 ## 多线程打印0-200
+系统学习多线程有感，再写这一题
+:::info
+多线程编程步骤:
+1. 创建资源类，在资源类中定义属性和方法
+2. 判断->干活->通知
+3. 创建多个线程调用资源类的方法
+:::
+```java
+class Share{
+    private int num = 0;
+    private boolean flag = true;
+    public synchronized boolean print1() throws InterruptedException {
+        //判断
+        while(!flag && num <= 200){
+            this.wait();
+        }
+        if(num > 200){
+        //避免有未唤醒的线程导致永远无法结束
+            notifyAll();
+            return false;
+        }
+        //干活
+        System.out.println(Thread.currentThread().getName() + "打印"+ num++);
+        flag = false;
+        //通知
+        this.notifyAll();
+        return true;
+    }
+    public synchronized boolean print2() throws InterruptedException {
+        //判断
+        while(flag && num <= 200){
+            this.wait();
+        }
+        if(num > 200){
+            notifyAll();
+            return false;
+        }
+        //干活
+        System.out.println(Thread.currentThread().getName() + "打印"+ num++);
+        flag = true;
+        //通知
+        this.notifyAll();
+        return true;
+    }
+    public synchronized int getNum(){
+        return this.num;
+    }
+}
+public class ConcurrentPrint {
+    public static void main(String[] args) {
+        Share share = new Share();
+        new Thread(()->{
+            while (true) {
+                try {
+                    if (!share.print1()) break;
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        },"A").start();
+        new Thread(()->{
+            while(true){
+                try {
+                    if (!share.print2()) break;
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        },"B").start();
 
+    }
+}
+```
 ```java
 public class Main {
     private static final int MAX = 200;