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| public class JTreeSelectionExample {
public static void main(String[] args) throws IOException {
JFrame frame = new JFrame("Démo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTree tree = new JTree(createTree());
tree.setScrollsOnExpand(true);
tree.setRootVisible(false);
tree.setShowsRootHandles(true);
for(KeyListener keyListener : tree.getKeyListeners()) {
tree.removeKeyListener(keyListener);
}
tree.addKeyListener(createKeyListener(tree));
frame.add(new JScrollPane(tree));
frame.setSize(600, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private static KeyListener createKeyListener(JTree tree) {
return new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
char c = e.getKeyChar();
TreeNode node;
TreePath current = tree.getSelectionPath();
if( current==null ) {
node = (TreeNode) tree.getModel().getRoot();
}
else {
node = getNextSibling((TreeNode) current.getLastPathComponent());
if ( node==null ) {
node = (TreeNode) tree.getModel().getRoot();
}
}
TreeNode nextNode = getNextNode(node, c);
if( nextNode==null ) {
nextNode = getNextNode((TreeNode)tree.getModel().getRoot(), c);
}
if( nextNode==null ) {
return;
}
TreePath path = createTreePath(nextNode);
tree.setSelectionPath(path);
tree.scrollPathToVisible(path);
}
private TreePath createTreePath(TreeNode node) {
Deque<TreeNode> stack = new ArrayDeque<>();
while(node!=null) {
stack.push(node);
node=node.getParent();
}
return new TreePath(stack.toArray());
}
private TreeNode getNextSibling(TreeNode node) {
TreeNode parent = node.getParent();
while ( parent!=null ) {
int index = parent.getIndex(node)+1;
if ( index<parent.getChildCount() ) {
return parent.getChildAt(index);
}
node = parent;
parent = node.getParent();
}
return null;
}
private TreeNode getNextNode(TreeNode node, char c) {
return getNextNode(node, c, true);
}
private TreeNode getNextNode(TreeNode node, char c, boolean nextSibling) {
if ( match(node,c) ) {
return node;
}
for(int i=0; i<node.getChildCount(); i++) {
TreeNode child = getNextNode(node.getChildAt(i), c, false);
if ( child!=null ) {
return child;
}
}
if (nextSibling) {
TreeNode parent = node.getParent();
while ( parent!=null ) {
int index = parent.getIndex(node)+1;
for(int i=index; i<parent.getChildCount(); i++) {
TreeNode child = getNextNode(parent.getChildAt(i), c, false);
if ( child!=null ) {
return child;
}
}
node = parent;
parent = node.getParent();
}
}
return null;
}
private boolean match(TreeNode node, char c) {
String s = node.toString();
return !s.isEmpty() && Character.toLowerCase(s.charAt(0))==Character.toLowerCase(c);
}
};
}
private static MutableTreeNode createTree() throws IOException {
DefaultMutableTreeNode root = new DefaultMutableTreeNode("");
createTree(root,FileSystemView.getFileSystemView().getHomeDirectory().toPath(),2);
return root;
}
private static void createTree(DefaultMutableTreeNode parent, Path dir, int depth) throws IOException {
StreamSupport.stream(Files.newDirectoryStream(dir).spliterator(),false)
.map(path-> createNode(path, depth))
.forEach(parent::add);
}
private static MutableTreeNode createNode(Path path, int depth) {
FileNode node = new FileNode(path);
if( depth>0 && Files.isDirectory(path) ) {
try {
createTree(node, path, depth-1);
} catch (IOException e) {
// ignore
}
}
return node;
}
private static class FileNode extends DefaultMutableTreeNode {
public FileNode(Path path) {
super(path.getFileName());
}
}
} |
