bugzilla 37184: multiple calls to addlistener for introspection helper objects

reporter:  Frank Harnack


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@328081 13f79535-47bb-0310-9956-ffa450edef68

CONTRIBUTORS

@@ -67,8 +67,9 @@ Erik Hatcher
 Erik Langenbach
 Erik Meade
 Ernst de Haan
-Frederic Lavigne
 Frank Somers
+Frank Harnack
+Frederic Lavigne
 Gary S. Weaver
 Gautam Guliani
 Gero Vermaas

WHATSNEW

@@ -147,6 +147,9 @@ Fixed bugs:
 * <cvschangelog> was crashing with CVS versions >= 1.12.x due to change in
   the date format. Bugzilla report 30962.
 
+* The same IntrospectionHelper instance was contineously added as a listener
+  to project. Bugzilla report 37184.
+
 Other changes:
 --------------
 * Fixed references to obsoleted CVS web site. Burzilla Report 36854.

src/main/org/apache/tools/ant/Project.java

@@ -327,6 +327,10 @@ public class Project {
      *                 Must not be <code>null</code>.
      */
     public synchronized void addBuildListener(BuildListener listener) {
+        // If the listeners already has this listener, do nothing
+        if (listeners.contains(listener)) {
+            return;
+        }
         // create a new Vector to avoid ConcurrentModificationExc when
         // the listeners get added/removed while we are in fire
         Vector newListeners = getBuildListeners();