Drag and Drop between JLists (1)

Sample code of using the DragSourceListener, DragGestureListener, and DropTargetListener to drag element from one list to another.

import java.awt.BorderLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.io.IOException;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JSplitPane;

public class DragDropDemo extends JFrame {
    private SourceList<String> source;
    private TargetList<String> target;
 
    public DragDropDemo() {
        source = new SourceList<String>(new String[]{"Papaya", "Orange", "Apple", "Mango", "Pear", "Avakado"});
        target = new TargetList<String>();
     
        JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, source, target);
        JLabel label = new JLabel("Please drag your selection from the left list to the right");
     
        add(splitPane);
        add(label, BorderLayout.NORTH);
        this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        pack();
        setVisible(true);
    }
 
    private class SourceList<E> extends JList implements DragSourceListener, DragGestureListener {
        DragSource dragSource;
     
        public SourceList(E[] data){
            super(data);
            dragSource = new DragSource();
            dragSource.createDefaultDragGestureRecognizer(this, DnDConstants.ACTION_COPY_OR_MOVE, this);
        }
     
        public void dragDropEnd(DragSourceDropEvent e){
            System.out.println("Finished dragging !");
        }
        public void dragExit(DragSourceEvent e){
            System.out.println("Exiting dragging !");
        }
        public void dropActionChanged(DragSourceDragEvent e){
            System.out.println("Changing drag action !");
        }
        public void dragOver(DragSourceDragEvent e){
            System.out.println("Over dragging !");
        }
        public void dragEnter(DragSourceDragEvent e){
            System.out.println("Entering dragging !");
        }
     
        public void dragGestureRecognized(DragGestureEvent e){
            Transferable transferable = new StringSelection((String)getSelectedValue());
            dragSource.startDrag(e, DragSource.DefaultCopyDrop, transferable, this);
        }
    }
 
    private class TargetList<E> extends JList implements DropTargetListener {
        DefaultListModel model = new DefaultListModel();
        public TargetList() {
            super();
            setModel(model);
            new DropTarget(this, this);
        }
     
        public void drop (DropTargetDropEvent e){
            Transferable transferable = e.getTransferable();
            if (!transferable.isDataFlavorSupported(DataFlavor.stringFlavor)){
                e.rejectDrop();
            }
            e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
            String dragged;
            try {
                dragged = (String)transferable.getTransferData(DataFlavor.stringFlavor);
                model.addElement(dragged);
                validate();
            }catch(UnsupportedFlavorException fe){
                e.rejectDrop();
            }catch(IOException ie){
                e.rejectDrop();
            }
        }

        public void dragExit(DropTargetEvent e) {
            System.out.println("Exiting Dropping !");
        }
     
        public void dropActionChanged(DropTargetDragEvent e){
            System.out.println("Changing Drop Action !");
        }
        public void dragOver(DropTargetDragEvent e){
            System.out.println("Over Dropping !");
        }
        public void dragEnter(DropTargetDragEvent e){
            System.out.println("Entering Dropping !");
        }
    }
 
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new DragDropDemo();
            }
        });
    }
}

Further Readings:
1. Drag and Drop between JLists (2)
2. Drag and Drop between JLists (3)

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