Transferable.getTransferData() throws java.io.IOException

Name: vi73552 Date: 03/04/99




I want to make a tree that accepts text dropped into it. I build
and run my example app. I bring up the wordpad windows app,
highlight some text and drag it into the tree in the jaja app.
An exception is thrown.

java.io.IOException: class java.awt.datatransfer.UnsupportedFlavorException:Plain Text caught while getting Data

at java.awt.dnd.DropTargetContext$TransferableProxy.getTransferData(DropTargetContext.java:270)

at TreePanel.drop(TreePanel.java:74)

at java.awt.dnd.DropTarget.drop(DropTarget.java:343)

at sun.awt.windows.WDropTargetContextPeer.processDropMessage(WDropTargetContextPeer.java:941)

at sun.awt.windows.WDropTargetContextPeer.run(WDropTargetContextPeer.java:472)

at javax.swing.SystemEventQueueUtilities.processRunnableEvent(SystemEventQueueUtilities.java:354)

at javax.swing.SystemEventQueueUtilities.access$0(SystemEventQueueUtilities.java:350)

at javax.swing.SystemEventQueueUtilities$RunnableTarget.processEvent(SystemEventQueueUtilities.java:391)

at java.awt.Component.dispatchEventImpl(Component.java:2376)

at java.awt.Component.dispatchEvent(Component.java:2289)

at java.awt.EventQueue.dispatchEvent(EventQueue.java:258)

at java.awt.EventDispatchThread.run(EventDispatchThread.java:68)


In my drop() method I have these two lines of code.

   if (trans.isDataFlavorSupported(DataFlavor.plainTextFlavor))
      obj = trans.getTransferData(DataFlavor.plainTextFlavor);

isDataFlavorSupported() returns true so I procede to getting the
data. But getTransferData() throws an exception even though the
previous call just returned true.


Here's my complete example.
**************************************************************
import java.awt.event.*;
import javax.swing.*;
import java.awt.dnd.*;
import java.awt.datatransfer.*;
import java.awt.event.*;
import java.io.*;



public class TreePanel
implements ActionListener, DropTargetListener
{
TreePanelUI view;
JTree tree;
DropTarget target;

public TreePanel()
{
view = new TreePanelUI();
tree = view.tree;
view.closeButton.addActionListener(this);
target = new DropTarget(tree, DnDConstants.ACTION_COPY, this);
target.setActive (true);
}

JPanel getView()
{ return view; }

public void actionPerformed(ActionEvent evt)
{
if(evt.getActionCommand().equals("Close"))
System.exit(0);
}

public void dragEnter (DropTargetDragEvent dtde)
{
System.out.println ("dragEnter");
DataFlavor df[] = dtde.getCurrentDataFlavors();
if (dtde.isDataFlavorSupported(DataFlavor.plainTextFlavor))
dtde.acceptDrag (DnDConstants.ACTION_COPY);
else
dtde.rejectDrag ();
}

public void dropActionChanged(DropTargetDragEvent dtde)
{ dragEnter(dtde); }

    public void dragOver (DropTargetDragEvent dtde)
{ System.out.println ("dragOver"); }

public void dragExit (DropTargetEvent dte)
{ System.out.println ("dragExit"); }

public void drop (DropTargetDropEvent dtde)
{
dtde.acceptDrop (DnDConstants.ACTION_COPY);

System.out.println ("dropped");

Transferable trans = dtde.getTransferable();
Object obj = null;

try
{
if (trans.isDataFlavorSupported(DataFlavor.plainTextFlavor))
             obj = trans.getTransferData(DataFlavor.plainTextFlavor);

System.out.println(obj);
if (obj != null && obj instanceof InputStream)
{
InputStream input = (InputStream) obj;
StringBuffer str = new StringBuffer();
byte[] buffer = new byte[64];
int count = input.read(buffer);
while (count != -1)
{
str.append (new String (buffer, 0, count));
count = input.read(buffer);
}
input.close();
//text.setText (str.toString());
}
} catch (Exception e) { e.printStackTrace(); }
finally
{
try { target.getDropTargetContext().dropComplete(true); }
catch (Exception ignore) {}
}
}
};

************************************************************
import javax.swing.*;
import java.awt.event.*;

public class TreeTest
implements ActionListener
{
public static void main(String args[])
{
System.out.println(System.getProperty("java.version"));
JFrame frame = new JFrame("JDK 1.2");
TreePanel panel = new TreePanel();
frame.getContentPane().add(panel.getView());
frame.setSize(300, 200);
frame.show();
}

  public void actionPerformed(ActionEvent e)
  { System.exit(0); }
}
*********************************************************
import javax.swing.*;
import java.beans.*;
import java.awt.*;

public class TreePanelUI extends javax.swing.JPanel
{
public TreePanelUI()
{

//{{INIT_CONTROLS
setLayout(new BorderLayout(0,0));
setSize(300,270);
add("Center",JScrollPane1);
JScrollPane1.setBounds(0,0,300,235);
JScrollPane1.getViewport().add(tree);
tree.setBounds(0,0,297,232);
JPanel1.setLayout(new FlowLayout(FlowLayout.CENTER,5,5));
add("South",JPanel1);
JPanel1.setBounds(0,235,300,35);
closeButton.setText("Close");
JPanel1.add(closeButton);
closeButton.setBounds(116,5,67,25);
//}}

//{{REGISTER_LISTENERS
//}}
}

//{{DECLARE_CONTROLS
javax.swing.JScrollPane JScrollPane1 = new javax.swing.JScrollPane();
javax.swing.JTree tree = new javax.swing.JTree();
javax.swing.JPanel JPanel1 = new javax.swing.JPanel();
javax.swing.JButton closeButton = new javax.swing.JButton();
//}}

}
(Review ID: 48238)
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