diff --git a/problems/0202.快乐数.md b/problems/0202.快乐数.md
index d6b1cdd2..8c0dd1e7 100644
--- a/problems/0202.快乐数.md
+++ b/problems/0202.快乐数.md
@@ -84,7 +84,28 @@ public:
 
 
 Java：
+```java
+class Solution {
+    public boolean isHappy(int n) {
+        Set<Integer> record = new HashSet<>();
+        while (n != 1 && !record.contains(n)) {
+            record.add(n);
+            n = getNextNumber(n);
+        }
+        return n == 1;
+    }
 
+    private int getNextNumber(int n) {
+        int res = 0;
+        while (n > 0) {
+            int temp = n % 10;
+            res += temp * temp;
+            n = n / 10;
+        }
+        return res;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0242.有效的字母异位词.md b/problems/0242.有效的字母异位词.md
index be553c5a..89186620 100644
--- a/problems/0242.有效的字母异位词.md
+++ b/problems/0242.有效的字母异位词.md
@@ -85,7 +85,25 @@ public:
 
 
 Java：
-
+```java
+class Solution {
+    public boolean isAnagram(String s, String t) {
+        int[] record = new int[26];
+        for (char c : s.toCharArray()) {
+            record[c - 'a'] += 1;
+        }
+        for (char c : t.toCharArray()) {
+            record[c - 'a'] -= 1;
+        }
+        for (int i : record) {
+            if (i != 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+```
 
 Python：
 
diff --git a/problems/0349.两个数组的交集.md b/problems/0349.两个数组的交集.md
index 75ef9061..b5116ee1 100644
--- a/problems/0349.两个数组的交集.md
+++ b/problems/0349.两个数组的交集.md
@@ -75,6 +75,7 @@ public:
 
 
 Java：
+
 ```Java
 import java.util.HashSet;
 import java.util.Set;