--- a/src/pagerank/LinkToVertex.java	Sat Sep 08 09:56:03 2012 +0900
+++ b/src/pagerank/LinkToVertex.java	Sat Sep 08 10:04:48 2012 +0900
@@ -253,8 +253,12 @@
 		return pageRank;
 	}
 	
-	public void printVertexInfo(int nodeId) {
-		Vertex v = graph.getVertex(nodeId);
+	public void printVertexInfo(Object id) {
+		Vertex v = graph.getVertex(id);
+		if (v == null) {
+			System.out.println(id+" is null.");
+			return;
+		}
 		printInHasLink(v, 1);
 		printOutHasLink(v, 1);
 
@@ -263,12 +267,15 @@
 		long inHasLink = computeInHasLink(v);
 		long outHasLink = computeOutHasLink(v);
 		
-		System.out.println("id:"+nodeId+" title:"+title+" rank:"+rank);
+		System.out.println("id:"+id+" title:"+title+" rank:"+rank);
 		System.out.println("inHasLink:"+inHasLink+" outHasLink:"+outHasLink);
 		System.out.println();
 	
 	}
 
-
+	public void printVertexInfo(String title) {
+		Object id = getId(title);
+		printVertexInfo(id);
+	}
 
 }