JTree with checkboxes

Question

I need to add checkboxes to a JTree. A custom TreeCellRenderer/TreeCellEditor seems like the right approach. So far I used the CheckBoxNodeRenderer approach in this webpage.

Answer 1

I have released a standalone Swing Checkbox Tree project, available from Maven Central as org.scijava:swing-checkbox-tree.

The package is based on John Zukowski's CheckBox Node Tree Sample code. It is BSD-2-licensed with no dependencies.

It allows mixing and matching of DefaultMutableTreeNode and CheckBoxNodeData node types. It also allows check box nodes as non-leaf nodes.

Regarding the question's issue #1: I did not test on all platforms, but on my OS X systems, the CheckBoxNodeData nodes are exactly the same height in pixels as the DefaultMutableTreeNode nodes.

Regarding the question's issue #2: it uses a JCheckBox + JLabel in a JPanel (as aperkins suggests) to differentiate between clicking on a check box (to check/uncheck a node) versus a label (to select a node).

Example usages:

• Simple: CheckBoxTreeSample
• Complex: WatchEventsFrame

The latter example also has code for recursively toggling subtrees in response to boxes being checked or unchecked (see the treeNodesChanged method).