From 938b4096086575b2bb8cc88b8985aea4bcfe314c Mon Sep 17 00:00:00 2001
From: Koichi Sakata <ksakata@openjdk.org>
Date: Fri, 27 Jan 2023 06:17:14 +0000
Subject: [PATCH] 8301133: IGV: NPE occurs when creating a diff graph with a
 graph in a different folder

Reviewed-by: rcastanedalo, chagedorn
---
 .../Data/src/main/java/com/sun/hotspot/igv/data/Group.java      | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/utils/IdealGraphVisualizer/Data/src/main/java/com/sun/hotspot/igv/data/Group.java b/src/utils/IdealGraphVisualizer/Data/src/main/java/com/sun/hotspot/igv/data/Group.java
index 5eb4b416ad7..28d9faafbb9 100644
--- a/src/utils/IdealGraphVisualizer/Data/src/main/java/com/sun/hotspot/igv/data/Group.java
+++ b/src/utils/IdealGraphVisualizer/Data/src/main/java/com/sun/hotspot/igv/data/Group.java
@@ -126,7 +126,7 @@ public class Group extends Properties.Entity implements ChangedEventProvider<Gro
 
     @Override
     public String getDisplayName() {
-        return getParent().getElements().indexOf(this)+1 + " - " + getName();
+        return (getParent() == null ? "" : getParent().getElements().indexOf(this) + 1 + " - ") + getName();
     }
 
     public String getType() {