louisfeng
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diff --git a/‎src/main/java/com/stevesun/solutions/_284.java
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@@ -201,6 +201,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |287|[Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)|[Solution](../master/src/main/java/com/stevesun/solutions/FindtheDuplicateNumber.java)| O(n)|O(1) | Medium| 
 |286|[Walls and Gates](https://leetcode.com/problems/walls-and-gates/)|[Solution](../master/src/main/java/com/stevesun/solutions/WallsAndGates.java)| O(m*n)|O(g) | Medium| BFS
 |285|[Inorder Successor In BST](https://leetcode.com/problems/inorder-successor-in-bst/)|[Solution](../master/src/main/java/com/stevesun/solutions/InorderSuccessorInBST.java)| O(h)|O(1) | Medium|
+|284|[Peeking Iterator](https://leetcode.com/problems/peeking-iterator/)|[Solution](../master/src/main/java/com/stevesun/solutions/_284.java)| O(n)|O(n) | Medium| Design
 |283|[Move Zeroes](https://leetcode.com/problems/move-zeroes/)|[Solution](../master/src/main/java/com/stevesun/solutions/MoveZeroes.java)| O(n)|O(1) | Easy| 
 |282|[Expression Add Operators](https://leetcode.com/problems/expression-add-operators/)|[Solution](../master/src/main/java/com/stevesun/solutions/ExpressionAddOperators.java)| O(?)|O(?) | Hard|
 |281|[Zigzag Iterator](https://leetcode.com/problems/zigzag-iterator/)|[Solution](../master/src/main/java/com/stevesun/solutions/_281.java)| O(n)|O(n) | Medium|
 
@@ -0,0 +1,51 @@
+package com.stevesun.solutions;
+
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * 284. Peeking Iterator
+ *
+ * Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation -- it essentially peek() at the element that will be returned by the next call to next().
+
+ Here is an example. Assume that the iterator is initialized to the beginning of the queue: [1, 2, 3].
+
+ Call next() gets you 1, the first element in the queue.
+
+ Now you call peek() and it returns 2, the next element. Calling next() after that still return 2.
+
+ You call next() the final time and it returns 3, the last element. Calling hasNext() after that should return false.
+
+ */
+public class _284 {
+    public static class PeekingIterator implements Iterator<Integer> {
+
+        private Queue<Integer> queue;
+        public PeekingIterator(Iterator<Integer> iterator) {
+            // initialize any member here.
+            queue = new LinkedList<>();
+            while (iterator.hasNext()) {
+                queue.add(iterator.next());
+            }
+        }
+
+        // Returns the next element in the iteration without advancing the iterator.
+        public Integer peek() {
+            return queue.peek();
+        }
+
+        // hasNext() and next() should behave the same as in the Iterator interface.
+        // Override them if needed.
+        @Override
+        public Integer next() {
+            return queue.poll();
+        }
+
+        @Override
+        public boolean hasNext() {
+            return !queue.isEmpty();
+        }
+    }
+}