From 63bbfb1a9fbf8e2dbfa7d5e529c34aaeb7d39c04 Mon Sep 17 00:00:00 2001
From: Axel Uhl <axel.uhl@sap.com>
Date: Fri, 14 Jul 2023 22:17:51 +0200
Subject: [PATCH] aftermath to 6ef57221e35d4c6c0afd9d5c05f828439cbdd481:
 avoiding NPE when waiting for listener thread

---
 .../markpassingcalculation/MarkPassingCalculator.java    | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/java/com.sap.sailing.domain/src/com/sap/sailing/domain/markpassingcalculation/MarkPassingCalculator.java b/java/com.sap.sailing.domain/src/com/sap/sailing/domain/markpassingcalculation/MarkPassingCalculator.java
index 0bfb3a9eeff..06d58dfb1c3 100755
--- a/java/com.sap.sailing.domain/src/com/sap/sailing/domain/markpassingcalculation/MarkPassingCalculator.java
+++ b/java/com.sap.sailing.domain/src/com/sap/sailing/domain/markpassingcalculation/MarkPassingCalculator.java
@@ -200,13 +200,14 @@ public class MarkPassingCalculator {
      */
     public void waitUntilStopped(final long timeoutInMillis) throws InterruptedException {
         final long start = System.currentTimeMillis();
-        if (listenerThread != null) {
-            synchronized (listenerThread) {
+        final Thread theListenerThread = listenerThread;
+        if (theListenerThread != null) {
+            synchronized (theListenerThread) {
                 while (!listenerThreadStarted && System.currentTimeMillis() - start < timeoutInMillis) {
-                    listenerThread.wait(timeoutInMillis);
+                    theListenerThread.wait(timeoutInMillis);
                 }
             }
-            listenerThread.join(timeoutInMillis);
+            theListenerThread.join(timeoutInMillis);
         }
     }