I'm trying to create a JList that allows you to re-order items in the list by dragging them. This is working OK, except the auto-scrolling behavior is very jerky and erratic. When I grab an item in the list and drag it to the bottom of the list, I expect it to scroll smoothly and continuously, but what I actually get is that it scrolls a few pixels and stops. If I jiggle the mouse cursor around the edge of the JList, then it continues scrolling a few pixels at a time, but clearly this is not acceptable behavior.
Does anybody have suggestions on how to fix this?
In case it matters, I'm running Java 6 on Mac OS X 10.8.3.
import javax.swing.*;
import java.awt.*;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
public class DraggableJList {
public static void main(String[] args) {
EventQueue.invokeLater( new Runnable() {
public void run() {
int count=200;
String[] elements = new String[count];
for(int n=0; n<count; n++ ) {
elements[n] = String.valueOf( n );
}
JList list = new JList( elements );
list.setDragEnabled( true ); //If I disable this line, the I get smooth scrolling, but I can't drag items to re-order them
list.setDropMode( DropMode.INSERT );
final TransferHandler transferHandler = new TransferHandler() {
@Override
public int getSourceActions( JComponent c ) {
return TransferHandler.MOVE;
}
@Override
protected Transferable createTransferable( JComponent c ) {
return new StringSelection( "Hey there" );
}
};
list.setTransferHandler( transferHandler );
JScrollPane scrollPane = new JScrollPane( list );
JFrame frame = new JFrame();
JPanel borderPanel = new JPanel();
borderPanel.add( scrollPane );
borderPanel.setBorder( BorderFactory.createEmptyBorder( 40, 40, 40, 40 ) );
frame.setContentPane( borderPanel );
frame.pack();
frame.setVisible( true );
}
} );
}
}
Did some searching and it turns out this is a known bug: