From 7d1b001c2fe50f9c22096efdc42a42b60d3ee2d6 Mon Sep 17 00:00:00 2001
From: haozhijie9527 <47975723+haozhijie9527@users.noreply.github.com>
Date: Mon, 13 Dec 2021 11:14:59 +0800
Subject: [PATCH] fix npe of SendMessageProcessorTest (#3632)
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Co-authored-by: haozhijie <“haozhijie_9527@163.com”>
---
 .../store/stats/BrokerStatsManager.java       | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/store/src/main/java/org/apache/rocketmq/store/stats/BrokerStatsManager.java b/store/src/main/java/org/apache/rocketmq/store/stats/BrokerStatsManager.java
index 466bf5e762..91de4a2c5d 100644
--- a/store/src/main/java/org/apache/rocketmq/store/stats/BrokerStatsManager.java
+++ b/store/src/main/java/org/apache/rocketmq/store/stats/BrokerStatsManager.java
@@ -195,25 +195,45 @@ public class BrokerStatsManager {
     }
 
     public String buildStatsKey(String topic, String group) {
-        StringBuilder strBuilder = new StringBuilder(topic.length() + group.length() + 1);
+        StringBuilder strBuilder;
+        if (topic != null && group != null) {
+            strBuilder = new StringBuilder(topic.length() + group.length() + 1);
+        } else {
+            strBuilder = new StringBuilder();
+        }
         strBuilder.append(topic).append("@").append(group);
         return strBuilder.toString();
     }
 
     public String buildStatsKey(String topic, int queueId) {
-        StringBuilder strBuilder = new StringBuilder(topic.length() + 5);
+        StringBuilder strBuilder;
+        if (topic != null) {
+            strBuilder = new StringBuilder(topic.length() + 5);
+        } else {
+            strBuilder = new StringBuilder();
+        }
         strBuilder.append(topic).append("@").append(queueId);
         return strBuilder.toString();
     }
 
     public String buildStatsKey(String topic, int queueId, String group) {
-        StringBuilder strBuilder = new StringBuilder(topic.length() + group.length() + 6);
+        StringBuilder strBuilder;
+        if (topic != null && group != null) {
+            strBuilder = new StringBuilder(topic.length() + group.length() + 6);
+        } else {
+            strBuilder = new StringBuilder();
+        }
         strBuilder.append(topic).append("@").append(queueId).append("@").append(group);
         return strBuilder.toString();
     }
 
     public String buildStatsKey(int queueId, String topic, String group) {
-        StringBuilder strBuilder = new StringBuilder(topic.length() + group.length() + 6);
+        StringBuilder strBuilder;
+        if (topic != null && group != null) {
+            strBuilder = new StringBuilder(topic.length() + group.length() + 6);
+        } else {
+            strBuilder = new StringBuilder();
+        }
         strBuilder.append(queueId).append("@").append(topic).append("@").append(group);
         return strBuilder.toString();
     }