Robert Hailey created TAP5-2745:
-----------------------------------
Summary: Tree component with empty list of root nodes causes
NullPointerException
Key: TAP5-2745
URL: https://issues.apache.org/jira/browse/TAP5-2745
Project: Tapestry 5
Issue Type: Bug
Components: tapestry-core
Affects Versions: 5.8.2
Reporter: Robert Hailey
An edge case, perhaps, but it seems as though attempting to create a Tree
component with no root nodes does not produce an empty list, but throws a null
pointer exception.
{noformat}
java.lang.NullPointerException: Cannot invoke
"org.apache.tapestry5.tree.TreeNode.getValue()" because "this.val$node" is null
at org.apache.tapestry5.corelib.components.Tree$4.render(Tree.java:169)
~[tapestry-core-5.8.2.jar:?]
at
org.apache.tapestry5.internal.services.RenderQueueImpl.run(RenderQueueImpl.java:79)
~[tapestry-core-5.8.2.jar:?]
at
org.apache.tapestry5.internal.services.PageRenderQueueImpl.render(PageRenderQueueImpl.java:121)
~[tapestry-core-5.8.2.jar:?]
{noformat}
To the best of my understanding, the fix is straight forward:
{noformat}
---
a/tapestry-core/src/main/java/org/apache/tapestry5/corelib/components/Tree.java
+++
b/tapestry-core/src/main/java/org/apache/tapestry5/corelib/components/Tree.java
@@ -265,7 +265,12 @@ public class Tree
writer.element("ul");
queue.push(RENDER_CLOSE_TAG);
- queue.push(toRenderCommand(nodes.first(), true));
+ TreeNode first = nodes.first();
+
+ if (first != null)
+ {
+ queue.push(toRenderCommand(first, true));
+ }
nodes.rest().each(new Worker<TreeNode>()
{
{noformat}
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