Changing component background while dragging over it

Question

I have a JPanel configured as a dropzone that lets the user drop files in it in order to be analyzed. Now I want to change the background color of that panel when the file is being dragged over it.

How can this be done?

The question is too broad start by checking https://docs.oracle.com/javase/tutorial/uiswing/dnd/intro.html, when you have implemented the drag and drop features, it will be fairly easy to also change the background of the JPanel (.setBackground) — Petter Friberg, Jul 13 '17 at 22:22
[That's one way you could do it](https://stackoverflow.com/questions/13597233/how-to-drag-and-drop-files-from-a-directory-in-java/13597635#13597635) - You could get the same affect by simply setting the background color to the desired color, but this allows for alpha based colors — MadProgrammer, Jul 13 '17 at 22:23

score 3 · Accepted Answer · edited Jul 16 '17 at 14:40

One way is to add a DropTarget. Something like this:

yourJpanel.setDropTarget(new DropTarget() {

    @Override
    public synchronized void drop(DropTargetDropEvent dtde)
    {
        this.changeToNormal();
        //handle the drop ....
    }

    @Override
    public synchronized void dragEnter(DropTargetDragEvent dtde){

        //Change JPANEL background...
        yourJpanel.setBackground(Color.RED);
    }

    @Override
        public synchronized void dragExit(DropTargetEvent dtde) {
        this.changeToNormal();
    }

    private void changeToNormal() {   
        //Set background to normal...
        yourJpanel.setBackground(Color.WHITE);
    }
});

Changing component background while dragging over it

1 Answers1