DndTree.java Source code

Introduction

Here is the source code for DndTree.java

Source

import java.awt.BorderLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;

import javax.swing.DropMode;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTree;
import javax.swing.TransferHandler;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreePath;

public class DndTree {
    public static void main(String args[]) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel top = new JPanel(new BorderLayout());
        JLabel dragLabel = new JLabel("Drag me:");
        JTextField text = new JTextField();
        text.setDragEnabled(true);
        top.add(dragLabel, BorderLayout.WEST);
        top.add(text, BorderLayout.CENTER);
        f.add(top, BorderLayout.NORTH);

        final JTree tree = new JTree();
        final DefaultTreeModel model = (DefaultTreeModel) tree.getModel();
        tree.setTransferHandler(new TransferHandler() {
            public boolean canImport(TransferHandler.TransferSupport support) {
                if (!support.isDataFlavorSupported(DataFlavor.stringFlavor) || !support.isDrop()) {
                    return false;
                }
                JTree.DropLocation dropLocation = (JTree.DropLocation) support.getDropLocation();
                return dropLocation.getPath() != null;
            }

            public boolean importData(TransferHandler.TransferSupport support) {
                if (!canImport(support)) {
                    return false;
                }
                JTree.DropLocation dropLocation = (JTree.DropLocation) support.getDropLocation();
                TreePath path = dropLocation.getPath();
                Transferable transferable = support.getTransferable();

                String transferData;
                try {
                    transferData = (String) transferable.getTransferData(DataFlavor.stringFlavor);
                } catch (IOException e) {
                    return false;
                } catch (UnsupportedFlavorException e) {
                    return false;
                }

                int childIndex = dropLocation.getChildIndex();
                if (childIndex == -1) {
                    childIndex = model.getChildCount(path.getLastPathComponent());
                }

                DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(transferData);
                DefaultMutableTreeNode parentNode = (DefaultMutableTreeNode) path.getLastPathComponent();
                model.insertNodeInto(newNode, parentNode, childIndex);

                TreePath newPath = path.pathByAddingChild(newNode);
                tree.makeVisible(newPath);
                tree.scrollRectToVisible(tree.getPathBounds(newPath));
                return true;
            }
        });

        JScrollPane pane = new JScrollPane(tree);
        f.add(pane, BorderLayout.CENTER);

        tree.setDropMode(DropMode.ON_OR_INSERT);
        f.setSize(300, 400);
        f.setVisible(true);
    }
}