diff --git a/doc/cheatsheet/java_trick.md b/doc/cheatsheet/java_trick.md
index 52bfe340..8dcc14a7 100644
--- a/doc/cheatsheet/java_trick.md
+++ b/doc/cheatsheet/java_trick.md
@@ -17,7 +17,7 @@
 
     - Define max-heap
         - LC 1046
-     ```java
+    ```java
     // java
     PriorityQueue<Integer> heap = new PriorityQueue<>(Comperator.reverseOrder());
     ```       
diff --git a/leetcode_java/src/main/java/dev/Test2.java b/leetcode_java/src/main/java/dev/Test2.java
index c440a4d0..891a22d0 100644
--- a/leetcode_java/src/main/java/dev/Test2.java
+++ b/leetcode_java/src/main/java/dev/Test2.java
@@ -1,8 +1,8 @@
 package dev;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
+import LeetCodeJava.DataStructure.TreeNode;
+
+import java.util.*;
 
 public class Test2 {
     public static void main(String[] args) {
@@ -34,6 +34,22 @@ public static void main(String[] args) {
         System.out.println(new int[]{1,2,3});
 
         List<Integer> x2 = new ArrayList<>(Arrays.asList(1, 2, 3));
+
+
+        // PriorityQueue for PriorityQueue
+        PriorityQueue<Integer> pq = new PriorityQueue<>();
+        pq.add(1);
+
+        // LinkedList for Queue
+        Queue<Integer> q = new LinkedList<>();
+        q.add(1);
+
+
+        String str = "abcd";
+
+        System.out.println(str);
+        System.out.println(str.indexOf(1));
+
     }
     
 }