[jboss-jira] [JBoss JIRA] Created: (JBRULES-722) NullPointerException when using inserAfter method with an empty LinkedList

[Pierre Paysant-Le Roux (JIRA)]

NullPointerException when using inserAfter method with an empty LinkedList
--------------------------------------------------------------------------

                 Key: JBRULES-722
                 URL: http://jira.jboss.com/jira/browse/JBRULES-722
             Project: JBoss Rules
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions: 3.1-m1
         Environment: Windows, jdk 1.5
            Reporter: Pierre Paysant-Le Roux
         Assigned To: Mark Proctor


JBoss rules throws a NullPointerException when adding my rules file. The problem is with the inserAfter methode in LinkedList. Debug shows that it appends when inserting a node in an empty list.
I wrote a simple test case to illustrate the problem :

Index: drools-core/src/test/java/org/drools/util/LinkedListTest.java
===================================================================
--- drools-core/src/test/java/org/drools/util/LinkedListTest.java	(revision 9968)
+++ drools-core/src/test/java/org/drools/util/LinkedListTest.java	(working copy)
@@ -264,4 +264,7 @@
                              3 );
     }
-}
\ No newline at end of file
+    public void testInsertAfter(){
+	this.list.insertAfter( null, this.node1 );
+    }
+}

And a patch to avoid the problem :

Index: drools-core/src/main/java/org/drools/util/LinkedList.java
===================================================================
--- drools-core/src/main/java/org/drools/util/LinkedList.java	(revision 9968)
+++ drools-core/src/main/java/org/drools/util/LinkedList.java	(working copy)
@@ -151,17 +151,21 @@
         }
 
         if ( existingNode == null ) {
-            // if existing node is null, then insert it as a first node
-            final LinkedListNode node = this.firstNode;
-            node.setPrevious( newNode );
-            newNode.setNext( node );
-            this.firstNode = newNode;
+        	if(this.isEmpty())
+        		this.add(newNode);
+        	else{
+        		// if existing node is null, then insert it as a first node
+        		final LinkedListNode node = this.firstNode;
+        		node.setPrevious( newNode );
+        		newNode.setNext( node );
+        		this.firstNode = newNode;
+        	}
         } else if ( existingNode == this.lastNode ) {
         	existingNode.setNext(newNode);
         	newNode.setPrevious( existingNode );
         	this.lastNode = newNode;
         } else {
-            ((LinkedListNode)existingNode.getNext()).setPrevious( newNode );
+        	((LinkedListNode)existingNode.getNext()).setPrevious( newNode );
             newNode.setNext( existingNode.getNext() );
             existingNode.setNext( newNode );
             newNode.setPrevious( existingNode );

Excuse me if I'm wrong.

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