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copied!<p>i tried the solution, you use, too.</p> <p>After my opinion the code presented there isn't optimal: - it calls tree.expandPath for all the nodes, instead of calling it only for the deepest non-leaf nodes (calling expandPath on leaf nodes has no effect, see the JDK)</p> <p>Here's a corrected version which should be faster:</p> <pre><code>// If expand is true, expands all nodes in the tree. // Otherwise, collapses all nodes in the tree. public void expandAll(JTree tree, boolean expand) { TreeNode root = (TreeNode)tree.getModel().getRoot(); if (root!=null) { // Traverse tree from root expandAll(tree, new TreePath(root), expand); } } /** * @return Whether an expandPath was called for the last node in the parent path */ private boolean expandAll(JTree tree, TreePath parent, boolean expand) { // Traverse children TreeNode node = (TreeNode)parent.getLastPathComponent(); if (node.getChildCount() > 0) { boolean childExpandCalled = false; for (Enumeration e=node.children(); e.hasMoreElements(); ) { TreeNode n = (TreeNode)e.nextElement(); TreePath path = parent.pathByAddingChild(n); childExpandCalled = expandAll(tree, path, expand) || childExpandCalled; // the OR order is important here, don't let childExpand first. func calls will be optimized out ! } if (!childExpandCalled) { // only if one of the children hasn't called already expand // Expansion or collapse must be done bottom-up, BUT only for non-leaf nodes if (expand) { tree.expandPath(parent); } else { tree.collapsePath(parent); } } return true; } else { return false; } } </code></pre>

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