更新了第202，242，349题

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：