Use drag and drop to reorder a list : JList « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. JList

import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragGestureRecognizer;
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 javax.swing.DefaultListModel;
import javax.swing.DropMode;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.TransferHandler;

public class DragDropList extends JList {
  DefaultListModel model;

  public DragDropList() {
    super(new DefaultListModel());
    model = (DefaultListModel) getModel();
    setDragEnabled(true);
    setDropMode(DropMode.INSERT);

    setTransferHandler(new MyListDropHandler(this));

    new MyDragListener(this);
    
    model.addElement("a");
    model.addElement("b");
    model.addElement("c");
  }

  public static void main(String[] a){
    JFrame f = new JFrame();
    f.add(new JScrollPane(new DragDropList()));
    f.setSize(300,300);
    f.setVisible(true);
  }
}

class MyDragListener implements DragSourceListener, DragGestureListener {
  DragDropList list;

  DragSource ds = new DragSource();

  public MyDragListener(DragDropList list) {
    this.list = list;
    DragGestureRecognizer dgr = ds.createDefaultDragGestureRecognizer(list,
        DnDConstants.ACTION_MOVE, this);

  }

  public void dragGestureRecognized(DragGestureEvent dge) {
    StringSelection transferable = new StringSelection(Integer.toString(list.getSelectedIndex()));
    ds.startDrag(dge, DragSource.DefaultCopyDrop, transferable, this);
  }

  public void dragEnter(DragSourceDragEvent dsde) {
  }

  public void dragExit(DragSourceEvent dse) {
  }

  public void dragOver(DragSourceDragEvent dsde) {
  }

  public void dragDropEnd(DragSourceDropEvent dsde) {
    if (dsde.getDropSuccess()) {
      System.out.println("Succeeded");
    } else {
      System.out.println("Failed");
    }
  }

  public void dropActionChanged(DragSourceDragEvent dsde) {
  }
}

class MyListDropHandler extends TransferHandler {
  DragDropList list;

  public MyListDropHandler(DragDropList list) {
    this.list = list;
  }

  public boolean canImport(TransferHandler.TransferSupport support) {
    if (!support.isDataFlavorSupported(DataFlavor.stringFlavor)) {
      return false;
    }
    JList.DropLocation dl = (JList.DropLocation) support.getDropLocation();
    if (dl.getIndex() == -1) {
      return false;
    } else {
      return true;
    }
  }

  public boolean importData(TransferHandler.TransferSupport support) {
    if (!canImport(support)) {
      return false;
    }

    Transferable transferable = support.getTransferable();
    String indexString;
    try {
      indexString = (String) transferable.getTransferData(DataFlavor.stringFlavor);
    } catch (Exception e) {
      return false;
    }

    int index = Integer.parseInt(indexString);
    JList.DropLocation dl = (JList.DropLocation) support.getDropLocation();
    int dropTargetIndex = dl.getIndex();

    System.out.println(dropTargetIndex + " : ");
    System.out.println("inserted");
    return true;
  }
}

14.40.JList
	14.40.1.	JList
	14.40.2.	Creating JList Components
	14.40.3.	Using JList
	14.40.4.	A container for pseud code
	14.40.5.	Storing value in Vector and adding them into JList
	14.40.6.	Set selected index
	14.40.7.	Modifying the Data Model
	14.40.8.	Using DefaultListModel to control the Data in a JList
	14.40.9.	Sharing the Data Model for a JComboBox and JList
	14.40.10.	Using a Custom Data Model
	14.40.11.	Listening to JList Events with a ListSelectionListener
	14.40.12.	Using ListDataListener to listen to ListModel Events
	14.40.13.	Selection event for double-clicking an item in the list
	14.40.14.	public Point indexToLocation(int index): returning a Point as the origin of the provided index
	14.40.15.	Setting the number of visible rows with setVisibleRowCount()
	14.40.16.	To programmatically move the list to the top
	14.40.17.	ListSelectionModel Modes
	14.40.18.	Selection Methods
	14.40.19.	To make multiple list selections, you can use the anchor and lead indices of the selection items.
	14.40.20.	Adding Element-Level Tooltips to List Items
	14.40.21.	Bench mark for JList
	14.40.22.	Customizing a JList Look and Feel
	14.40.23.	Get index of first visible item
	14.40.24.	Get index of last visible item
	14.40.25.	Arranging Items in a JList Component
	14.40.26.	Setting a Tool Tip for an Item in a JList Component
	14.40.27.	Detecting Double and Triple Clicks on an Item in a JList Component
	14.40.28.	Methods are used to find an item
	14.40.29.	Use drag and drop to reorder a list
	14.40.30.	These methods can be used to find the range of visible items