Lista Drag&Drop w Java

00:04 drag and drop , list rozwijana 0 Comments

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;
  static String[] elements = {"1a","2a","3a"};
  
  public DragDropList(String [] elements) {
    super(new DefaultListModel());
    model = (DefaultListModel) getModel();
    setDragEnabled(true);
    setDropMode(DropMode.INSERT);
    setTransferHandler(new MyListDropHandler(this));

    new MyDragListener(this);
    for (int i = 0, n = elements.length; i < n; i++) {
        model.addElement(elements[i]);
    }


  }

  public static void main(String[] a){
    JFrame f = new JFrame();
    
    f.add(new JScrollPane(new DragDropList(elements)));
    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;
  }
}