Mega Code Archive
Use drag and drop to reorder a list
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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;
}
}
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