diff --git a/JAVA/SlidingWindow.java b/JAVA/SlidingWindow.java
new file mode 100644
index 0000000..087ca1a
--- /dev/null
+++ b/JAVA/SlidingWindow.java
@@ -0,0 +1,33 @@
+// 239. Sliding Window Maximum
+// https://leetcode.com/problems/sliding-window-maximum/
+
+import java.util.*; 
+class Solution {
+    public int[] maxSlidingWindow(int[] a, int k) {
+        int n = a.length;
+        Deque<Integer> dq = new LinkedList<>();
+        int ans[] = new int[n-k+1];
+        int i = 0;
+        for(;i<k;i++){
+            while(!dq.isEmpty() && a[dq.peekLast()] <= a[i]){
+                dq.removeLast();
+            }
+            dq.addLast(i);
+        }
+        
+        for(;i<n ; i++)
+        {
+            ans[i-k] = a[dq.peekFirst()];
+            while(!dq.isEmpty() && dq.peekFirst() <= i-k){
+                dq.removeFirst();
+            }
+            while(!dq.isEmpty() && a[dq.peekLast()] <= a[i]){
+                dq.removeLast();
+            }
+            dq.addLast(i);
+        }
+        ans[i-k] = a[dq.peekFirst()];
+        
+        return ans; 
+        }
+}
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