--- a/src/main/java/jp/ac/u_ryukyu/ie/cr/jungle/transaction/node/redBlackTree/RedBlackTreeNodeAttribute.java	Thu Jan 05 21:56:24 2017 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/jungle/transaction/node/redBlackTree/RedBlackTreeNodeAttribute.java	Thu Jan 05 22:13:54 2017 +0900
@@ -79,18 +79,37 @@
     }
 
     @Override
-    public Iterator<String> getKeys() {
-        return null;
+    public Iterator<String> getKeys()  {
+        return attrs.keys();
     }
 
     @Override
     public boolean contain(String key) {
-        return false;
+        if (key.equals(balanceKey))
+            return true;
+        return attrs.contain(key);
     }
 
     @Override
     public Iterator<String> getFilteringKey(List<String> filter) {
-        return null;
+        return new Iterator<String>(){
+            String next = balanceKey;
+            Iterator<String> keys = attrs.keys();
+            @Override
+            public boolean hasNext() {
+                return next != null;
+            }
+
+            @Override
+            public String next() {
+                String key = next;
+                if (keys.hasNext())
+                    next = keys.next();
+                else
+                    next = null;
+                return key;
+            }
+        };
     }
 
 }