diff --git a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode343.java b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode343.java
index b175bd8..d067ddb 100644
--- a/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode343.java
+++ b/src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode343.java
@@ -45,7 +45,46 @@ public class LeetCode343 {
     static Object o = new Object();
     static int count = 0;
 
+    static class syn{
+        public static void main(String[] args) throws InterruptedException {
+            syn syn = new syn();
+            // 创建一个线程来调用 printSyn 方法
+            Thread thread1 = new Thread(() -> {
+                try {
+                    syn.printSyn();
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            });
+            // 创建另一个线程来调用 getLock 方法
+            Thread thread2 = new Thread(() -> {
+                syn.getLock();
+            });
+            thread1.start();
+            thread2.start();
+        }
+
+        public synchronized void printSyn() throws InterruptedException {
+            Thread.sleep(1000); // 睡眠，看this是不是被其他线程拿走了
+            // 睡眠的过程中拿着this，下面的this不能拿到
+            this.wait(); // 卡在这
+            System.out.println("syn");
+        }
+
+        // 另一个线程尝试去获取this对象
+        public synchronized void getLock() {
+            System.out.println(this);
+        }
+    }
+
     public static void main(String[] args) {
+        int a = 100;
+        long b = 100L;
+        System.out.println(a==b);
+
+        float c =  1.0f;
+        int d = 1;
+        System.out.println(c==d);
 
         new Thread(() -> {
             for (int i = 0; i < 100; i++) {