--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/BlackNode.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/BlackNode.java	Sun Mar 29 20:57:39 2015 +0900
@@ -16,6 +16,11 @@
     }
 
     @Override
+    protected boolean exitNode() {
+        return true;
+    }
+
+    @Override
     public Node<K,V> createNode(K key, V value, Node<K, V> left, Node<K, V> right) {
         return new BlackNode<K, V>(key, value, left, right);
     }

--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/EmptyNode.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/EmptyNode.java	Sun Mar 29 20:57:39 2015 +0900
@@ -14,6 +14,11 @@
     }
 
     @Override
+    protected boolean exitNode() {
+        return false;
+    }
+
+    @Override
     public Node<K, V> clone() {
         return new EmptyNode<K, V>();
     }

--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/Node.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/Node.java	Sun Mar 29 20:57:39 2015 +0900
@@ -28,9 +28,11 @@
         return left;
     }
 
+
     public Optional<V> get(Comparable<? super K> key) {
 
         int result = key.compareTo(getKey());
+
         if (result > 0)
             return right().get(key);
 
@@ -38,11 +40,32 @@
             return left().get(key);
 
         else if (result == 0)
-            return Optional.ofNullable((V) getValue());
+            return Optional.ofNullable(getValue());
 
         return Optional.ofNullable(null);
     }
 
+    public Optional<V> getLoop(Comparable<? super K> key) {
+
+        Node<K, V> cur = this;
+        do {
+            int result = key.compareTo(cur.getKey());
+
+            if (result > 0)
+                cur = cur.right();
+
+            else if (result < 0)
+                cur = cur.left();
+
+            else if (result == 0)
+                return Optional.ofNullable(cur.getValue());
+
+        } while (cur.exitNode());
+
+        return Optional.ofNullable(null);
+    }
+
+
     public Node<K, V> right() {
         return right;
     }
@@ -75,6 +98,9 @@
 
     public abstract Node clone();
 
+
+    protected abstract boolean exitNode();
+
     public abstract Node<K, V> createNode(K key, V value, Node<K, V> left, Node<K, V> right);
 
     abstract Node<K, V> balance();

--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/RedNode.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/RedNode.java	Sun Mar 29 20:57:39 2015 +0900
@@ -19,6 +19,11 @@
     }
 
     @Override
+    protected boolean exitNode() {
+        return true;
+    }
+
+    @Override
     public Node<K,V> createNode(K key, V value, Node<K, V> left, Node<K, V> right) {
         return new RedNode<K,V>(key, value, left, right);
     }

--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/TreeMap.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/TreeMap/TreeMap.java	Sun Mar 29 20:57:39 2015 +0900
@@ -30,7 +30,10 @@
 
     public Optional<V> get(K key) {
         return root.get((Comparable<? super K>) key);
+    }
 
+    public Optional<V> getLoop(K key) {
+        return root.getLoop((Comparable<? super K>) key);
     }
 
     public TreeMap put(K key, V value) {

--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/test/TreeMapTest.java	Thu Mar 26 12:10:56 2015 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/tatsuki/test/TreeMapTest.java	Sun Mar 29 20:57:39 2015 +0900
@@ -22,7 +22,7 @@
 
         for (int count = 100; count > -10; count--) {
 
-            Optional<Integer> op = map.get(count);
+            Optional<Integer> op = map.getLoop(count);
             if (op.isPresent())
                 System.out.println(op.get());
         }