X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Fjalview%2Fstructure%2FStructureSelectionManager.java;h=8d684c1d598b8f0590541c987a94dd43797d78b0;hb=416f6e172aa77e3b0f2c2bd2b7a5655a6194d936;hp=a76a27ef3eb4efb36f7465eacab1da3f0ac2fa53;hpb=b57a02c25e335d033c97f8a6bacd6b54f62bd2b6;p=jalview.git

diff --git a/src/jalview/structure/StructureSelectionManager.java b/src/jalview/structure/StructureSelectionManager.java
index a76a27e..8d684c1 100644
--- a/src/jalview/structure/StructureSelectionManager.java
+++ b/src/jalview/structure/StructureSelectionManager.java
@@ -1,13 +1,13 @@
 /*
- * Jalview - A Sequence Alignment Editor and Viewer (Version 2.7)
- * Copyright (C) 2011 J Procter, AM Waterhouse, J Engelhardt, LM Lui, G Barton, M Clamp, S Searle
+ * Jalview - A Sequence Alignment Editor and Viewer (Version 2.8)
+ * Copyright (C) 2012 J Procter, AM Waterhouse, LM Lui, J Engelhardt, G Barton, M Clamp, S Searle
  * 
  * This file is part of Jalview.
  * 
  * Jalview is free software: you can redistribute it and/or
  * modify it under the terms of the GNU General Public License 
  * as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
- * 
+ *  
  * Jalview is distributed in the hope that it will be useful, but 
  * WITHOUT ANY WARRANTY; without even the implied warranty 
  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
@@ -53,10 +53,26 @@ public class StructureSelectionManager
   }
 
   Hashtable mappingData = new Hashtable();
-
+  private static StructureSelectionManager nullProvider = null;
   public static StructureSelectionManager getStructureSelectionManager(
           StructureSelectionManagerProvider context)
   {
+    if (context==null) { 
+      if (nullProvider == null)
+      {
+        if (instances != null)
+        {
+          throw new Error(
+                  "Implementation error. Structure selection manager's context is 'null'",
+                  new NullPointerException("SSM context is null"));
+        }
+        else
+        {
+          nullProvider = new StructureSelectionManager();
+        }
+        return nullProvider;
+      }
+    }
     if (instances == null)
     {
       instances = new java.util.IdentityHashMap<StructureSelectionManagerProvider, StructureSelectionManager>();
@@ -64,7 +80,13 @@ public class StructureSelectionManager
     StructureSelectionManager instance = instances.get(context);
     if (instance == null)
     {
-      instances.put(context, instance = new StructureSelectionManager());
+      if (nullProvider!=null)
+      {
+        instance = nullProvider;
+      } else {
+        instance = new StructureSelectionManager();
+      }
+      instances.put(context, instance);
     }
     return instance;
   }