feat(ml):$219.contains-duplicate-ii.md (#447)

Author: ztianming

problems/219.contains-duplicate-ii.md

@@ -51,7 +51,7 @@ https://leetcode-cn.com/problems/contains-duplicate-ii/
 
 ## 代码
 
-* 语言支持：JS，Python，C++
+* 语言支持：JS，Python，C++, Java
 
 Javascript Code:
 
@@ -86,6 +86,7 @@ class Solution:
             d[num] = index
         return False
 ```
+
 C++ Code：
 ```C++
 class Solution {
@@ -106,6 +107,25 @@ public:
 };
 ```
 
+Java Code:
+
+```java
+class Solution {
+    public boolean containsNearbyDuplicate(int[] nums, int k) {
+        Map<Integer, Integer> map = new HashMap<>();
+        for(int i=0;i<nums.length;i++)
+        {
+            if(map.get(nums[i]) != null && (i-map.get(nums[i])) <= k)
+            {
+                return true;
+            }
+            map.put(nums[i], i);
+        }
+        return false;
+    }
+}
+```
+
 **复杂度分析**
 - 时间复杂度：$O(N)$
 - 空间复杂度：$O(N)$