Model.java 文件源码

@Override
public void treeExpanded(final TreeExpansionEvent event) {
    final TreePath treePath = event.getPath();

    final Object expandedTreePathObject = treePath.getLastPathComponent();
    if (!(expandedTreePathObject instanceof TreeNode)) {
        return;
    }

    final TreeNode expandedTreeNode = (TreeNode) expandedTreePathObject;
    if (expandedTreeNode.getChildCount() == 1) {
        final TreeNode descendantTreeNode = expandedTreeNode.getChildAt(0);

        if (descendantTreeNode.isLeaf()) {
            return;
        }

        final TreePath nextTreePath = treePath.pathByAddingChild(descendantTreeNode);
        tree.expandPath(nextTreePath);
    }
}