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Drag two images and drop them in two different JButtons in the same JFrame

I have a code in which I must drag two images from my desktop and drop it on a frame in two draggable buttons. The buttons have already been made on the frame. But while dragging the images, they can only be dragged to one button. The images don't get dragged to the other one. I have made a DragListener class where the dragging methods prevail and the main class DragInitialListener where I have passed objects of class DragButton so that two draggable buttons are created. I have tried everything I could think of, made two DragListener classes, passed the methods differently but the image could only be dragged in one button. I want both the buttons to be able to hold images. Please help me with it. Here's the code that I have made so far:
//This is the main class
public class DragInitialListener extends javax.swing.JFrame {
private volatile int draggedAtX, draggedAtY;
public DragInitialListener() {
initComponents();
Droptargets();
Droptarget();
}
public void Droptarget()
{
DragListener d;
DragButton db = new DragButton();
db.setSize(170,140);
d= new DragListener(db);
DropTarget drop = new DropTarget(this,d);
this.getContentPane().add(db);
}
public void Droptargets()
{
DragListener dd;
DragButton db1 = new DragButton();
db1.setSize(170,140);
dd= new DragListener(db1);
DropTarget drop1 = new DropTarget(this,dd);
this.getContentPane().add(db1);
}
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
public static void main(String args[]) {
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new DragInitialListener().setVisible(true);
}
});
}
// Variables declaration - do not modify
// End of variables declaration
}
//This is the DragListener class
public class DragListener extends JButton implements DropTargetListener
{
JButton imagebutton = new JButton();
// JButton imagebutton1 = new JButton();
private volatile int draggedAtX, draggedAtY;
DragListener(JButton image) {
imagebutton=image;
}
#Override
public void dragEnter(DropTargetDragEvent dtde) {
}
#Override
public void dragOver(DropTargetDragEvent dtde) {
}
#Override
public void dropActionChanged(DropTargetDragEvent dtde) {
}
#Override
public void dragExit(DropTargetEvent dte) {
}
#Override
public void drop(DropTargetDropEvent ev) {
ev.acceptDrop(DnDConstants.ACTION_COPY);
Transferable t = ev.getTransferable();
//DropTarget test = (DropTarget) ev.getSource();
DataFlavor[] df= t.getTransferDataFlavors();
for(DataFlavor f:df)
{
try
{
if(f.isFlavorJavaFileListType())
{
List<File> files =(List<File>) t.getTransferData(f);
for(File file : files)
{
displayImage(file.getPath());
}
}
}
catch(Exception ex)
{
JOptionPane.showMessageDialog(null, ex);
}
}
}
private void displayImage(String path)
{
BufferedImage img = null;
try
{
img =ImageIO.read(new File(path));
}
catch(Exception e)
{
}
ImageIcon icon = new ImageIcon(img);
imagebutton.setIcon(icon);
}
}

Start simple, get one button to work, if you can get one to work, you can get 100 to work
This is a very simple example, which makes use of the transfer API, because you really only care about dropping and not dragging
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.io.File;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.TransferHandler;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
JButton btn = new JButton("Drop here");
btn.setVerticalTextPosition(JButton.BOTTOM);
btn.setHorizontalTextPosition(JButton.CENTER);
btn.setTransferHandler(new ImageTransferHandler());
add(btn);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
public static class ImageTransferHandler extends TransferHandler {
public static final DataFlavor[] SUPPORTED_DATA_FLAVORS = new DataFlavor[]{
DataFlavor.javaFileListFlavor,
DataFlavor.imageFlavor
};
#Override
public boolean canImport(TransferHandler.TransferSupport support) {
boolean canImport = false;
for (DataFlavor flavor : SUPPORTED_DATA_FLAVORS) {
if (support.isDataFlavorSupported(flavor)) {
canImport = true;
break;
}
}
return canImport;
}
#Override
public boolean importData(TransferHandler.TransferSupport support) {
boolean accept = false;
if (canImport(support)) {
try {
Transferable t = support.getTransferable();
Component component = support.getComponent();
if (component instanceof JButton) {
Image image = null;
if (support.isDataFlavorSupported(DataFlavor.imageFlavor)) {
image = (Image) t.getTransferData(DataFlavor.imageFlavor);
} else if (support.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
List files = (List) t.getTransferData(DataFlavor.javaFileListFlavor);
if (files.size() > 0) {
image = ImageIO.read((File) files.get(0));
}
}
ImageIcon icon = null;
if (image != null) {
icon = new ImageIcon(image);
}
((JButton) component).setIcon(icon);
accept = true;
}
} catch (Exception exp) {
exp.printStackTrace();
}
}
return accept;
}
}
}
So, by doing nothing more then changing the layout and replicating the button using
public TestPane() {
setLayout(new GridLayout(5, 5));
for (int index = 0; index < 5 * 5; index++) {
JButton btn = new JButton("Drop here");
btn.setVerticalTextPosition(JButton.BOTTOM);
btn.setHorizontalTextPosition(JButton.CENTER);
btn.setTransferHandler(new ImageTransferHandler());
add(btn);
}
}
I was able to achieve...
Updated...
So apparently I might have misunderstood the question, not the first time. From what's been explained to me, you might want to drag multiple images and have them applied to the buttons. Surprising, the process doesn't change that much.
In this example, I've applied the TransferHandler to the JPanel instead of the button and supplied it the buttons I want updated. You could easily update this to have a variable number of buttons, but I've started with two.
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.io.File;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.TransferHandler;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
JButton left = makeButton("Left");
JButton right = makeButton("Right");
add(left);
add(right);
setTransferHandler(new ImageTransferHandler(left, right));
}
protected JButton makeButton(String text) {
JButton btn = new JButton(text);
btn.setVerticalTextPosition(JButton.BOTTOM);
btn.setHorizontalTextPosition(JButton.CENTER);
return btn;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
public static class ImageTransferHandler extends TransferHandler {
public static final DataFlavor[] SUPPORTED_DATA_FLAVORS = new DataFlavor[]{
DataFlavor.javaFileListFlavor,};
private JButton left, right;
public ImageTransferHandler(JButton left, JButton right) {
this.left = left;
this.right = right;
}
#Override
public boolean canImport(TransferHandler.TransferSupport support) {
boolean canImport = false;
for (DataFlavor flavor : SUPPORTED_DATA_FLAVORS) {
if (support.isDataFlavorSupported(flavor)) {
canImport = true;
break;
}
}
return canImport;
}
#Override
public boolean importData(TransferHandler.TransferSupport support) {
boolean accept = false;
if (canImport(support)) {
try {
Transferable t = support.getTransferable();
Image image = null;
if (support.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
List files = (List) t.getTransferData(DataFlavor.javaFileListFlavor);
JButton buttons[] = new JButton[]{left, right};
for (int index = 0; index < Math.min(files.size(), 2); index++) {
if (files.size() > 0) {
image = ImageIO.read((File) files.get(index));
ImageIcon icon = null;
if (image != null) {
icon = new ImageIcon(image);
}
buttons[index].setIcon(icon);
}
}
accept = true;
}
} catch (Exception exp) {
exp.printStackTrace();
}
}
return accept;
}
}
}
Now, there are rules you will need to define yourself, for example, what happens when the user only drags a single image? Do you apply it to the first button (as I have) every time, or do you try and find the button without an image and update it? What happens if all the buttons have images? Where does it go then?
Do you reject drags with more than 2 images?

jbutton does not work

Hi I have the following code where I have a start and stop button . when start is pressed canvas starts painting but I cannot press stop button until the start operation is done . I need to stop and resume the paint on the button press . Once the start button is pressed the other buttons cannot be pressed till the canvas is painted.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Hashtable;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.Timer;
public abstract class JUIApp extends JPanel implements ActionListener {
public static CACanvas cacanvas= null;
public ArrayList<int[]> genL;
public JFrame frame = null;
protected JPanel mainPanel = null;
private JButton btn0 = null;
private JButton btn1 = null;
private JButton btn2 = null;
#SuppressWarnings("rawtypes")
DefaultComboBoxModel rules = null;
#SuppressWarnings("rawtypes")
JComboBox rulesCombo =null;
JScrollPane ruleListScrollPane=null;
JLabel lable=null;
JTextField generation=null;
JLabel gLable=null;
public static String Rule;
public static String Generations;
public boolean isChanged =false;
public int gridCellSize=4;
private static final long serialVersionUID = 1L;
public int genCurrent=0;
public int posCurrent=0;
public int i;
public Color cellColor= null;
public Timer waitTimer;
public static boolean waitFlag;
public static boolean alert1Flag=false;
public boolean stopFlag=false;
public JLabel Alert1=new JLabel();
public int genCheck=0;
//private List<Point> fillCells;
public JUIApp() {
initGUI();
}
public void initGUI() {
//fillCells = new ArrayList<>(25);
frame = new JFrame();
frame.setTitle("Cellular Automata Demo");
frame.setSize(1050, 610);
frame.setResizable(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(getMainPanel(),BorderLayout.NORTH);
frame.setVisible(true);
Toolkit.getDefaultToolkit().setDynamicLayout(false);
cacanvas=new CACanvas();
frame.add(cacanvas);
}
#SuppressWarnings({ "unchecked", "rawtypes" })
public JPanel getMainPanel() {
mainPanel = new JPanel();
mainPanel.setLayout(new FlowLayout());
//cacanvas=new CACanvas();
btn0 = new JButton("Start");
btn0.addActionListener(this);
//waitTimer = new Timer(1000, this);
mainPanel.add(btn0);
JButton btn2 = new JButton("Stop");
btn2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent s)
{
stopFlag=true;
//cacanvas.repaint();
}
});
mainPanel.add(btn2);
btn1 = new JButton("Clear");
btn1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
CACanvas.clearFlag=true;
generation.setText("");
alert1Flag=true;
rulesCombo.setSelectedIndex(0);
Alert1.setText("Please enter the number of generations");
Alert1.setBounds(30, 20, 5, 5);
Alert1.setVisible(alert1Flag);
mainPanel.add(Alert1);
cacanvas.repaint();
frame.setSize(1060, 610);
}
});
mainPanel.add(btn1);
lable=new JLabel();
lable.setText("Select Rule :");
mainPanel.add(lable);
rules=new DefaultComboBoxModel();
for (int i=0;i<=100;i++)
{
String p=String.valueOf(i);
rules.addElement(p);
}
rules.addElement("250");
rules.addElement("254");
rulesCombo = new JComboBox(rules);
rulesCombo.setSelectedIndex(0);
ruleListScrollPane = new JScrollPane(rulesCombo);
mainPanel.add(ruleListScrollPane);
//mainPanel.revalidate();
gLable=new JLabel();
gLable.setText("Enter the number of Generations (Max 64)");
generation=new JTextField(2);
mainPanel.add(gLable);
mainPanel.add(generation);
// mainPanel.add(cacanvas);
return mainPanel;
}
public abstract void run();
#Override
public void actionPerformed(ActionEvent arg0) {
Alert1.setVisible(false);
waitFlag=false;
System.out.println("We received an ActionEvent " + arg0);
Generations=generation.getText();
System.out.println(Generations);
Rule = "";
if (rulesCombo.getSelectedIndex() != -1) {
Rule =
(String) rulesCombo.getItemAt
(rulesCombo.getSelectedIndex());
}
System.out.println(Rule);
int rule=Integer.parseInt(Rule);
Hashtable<String,Integer> rules= new Hashtable<String,Integer>();
CARule ruleClass=new CARule();
rules=ruleClass.setRule(rule);
CAGenetationSet sa =new CAGenetationSet(100, false,rules);
genL=new ArrayList<int[]>();
genL=sa.runSteps(Integer.parseInt(Generations));
System.out.println("calling pattern set");
for(int i=0;i<=genL.size()-1;i++)
{
System.out.println("Painting generation :"+i);
if(stopFlag==false)
{
cacanvas.repaint();
}
//genPaint();
//sleep();
int[] newCell=genL.get(i);
for(int r=0;r<newCell.length;r++)
{
if(newCell[r]==1)
{
System.out.println("Generaton is"+i+"CellLife is"+r);
cacanvas.fillCell(i,r);
}
}
}
/*cacanvas.patternSet(genL);
waitFlag=true;
System.out.println("run completed");
// cacanvas.clearFlag=true;
*/
}
public void genPaint()
{
cacanvas.repaint();
}
public void sleep()
{
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
public static void main(String[] args) {
JUIApp app = new JUIApp() {
#Override
public void run() {
// TODO Auto-generated method stub
System.out.println("Run method");
}
};
}
}

Seems like you are using the current Thread on that task, you should create another Thread and add one listeners code to the new Thread.

MVC Pattern JButton ActionListener not Responding

So I'm trying to create a simple test program where the user can enter something into a JTextField, click the "add" JButton, and a JTextArea will add the users string to the the JTextArea (continuously appending with new line).
I added the actionListener for the button and have a stateChanged and an update method, but nothing happens when I click the add button. No errors either. Could someone please point me in the right direction?
Here's my code:
MVCTester (main)
public class MVCTester {
public static void main(String[] args) {
// TODO Auto-generated method stub
MVCController myMVC = new MVCController();
MVCViews myViews = new MVCViews();
myMVC.attach(myViews);
}
}
MVCController
import java.util.ArrayList;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class MVCController {
MVCModel model;
ArrayList<ChangeListener> listeners;
public MVCController(){
model = new MVCModel();
listeners = new ArrayList<ChangeListener>();
}
public void update(String input){
model.setInputs(input);
for (ChangeListener l : listeners)
{
l.stateChanged(new ChangeEvent(this));
}
}
public void attach(ChangeListener c)
{
listeners.add(c);
}
}
MVCModel
import java.util.ArrayList;
public class MVCModel {
private ArrayList<String> inputs;
MVCModel(){
inputs = new ArrayList<String>();
}
public ArrayList<String> getInputs(){
return inputs;
}
public void setInputs(String input){
inputs.add(input);
}
}
MVCViews
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class MVCViews implements ChangeListener {
private JTextField input;
private JTextArea echo;
private ArrayList<String> toPrint = new ArrayList<String>();
MVCController controller;
MVCViews(){
controller = new MVCController();
JPanel myPanel = new JPanel();
JButton addButton = new JButton("add");
echo = new JTextArea(10,20);
echo.append("Hello there! \n");
echo.append("Type something below!\n");
myPanel.setLayout(new BorderLayout());
myPanel.add(addButton, BorderLayout.NORTH);
input = new JTextField();
final JFrame frame = new JFrame();
frame.add(myPanel, BorderLayout.NORTH);
frame.add(echo, BorderLayout.CENTER);
frame.add(input, BorderLayout.SOUTH);
addButton.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
controller.update(input.getText());
}
});
frame.pack();
frame.setVisible(true);
}
#Override
public void stateChanged(ChangeEvent e) {
// TODO Auto-generated method stub
toPrint = controller.model.getInputs();
for(String s: toPrint){
echo.append(s + "\n");
}
}
}
This is my first time trying to follow MVC format, so there might be issues with the model itself as well. Feel free to point them out. Thank you for your help!

The controller within the GUI is not the same controller that is created in main. Note how many times you call new MVCController() in your code above -- it's twice. Each time you do this, you're creating a new and distinct controller -- not good. Use only one. You've got to pass the one controller into the view. You can figure out how to do this. (hint, a setter or constructor parameter would work).
hint 2: this could work: MVCViews myViews = new MVCViews(myMVC);
one solution:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class MVCTester {
public static void main(String[] args) {
MVCController myMVC = new MVCController();
MVCViews myViews = new MVCViews(myMVC);
myMVC.attach(myViews);
// myViews.setController(myMVC); // or this could do it
}
}
class MVCController {
MVCModel model;
ArrayList<ChangeListener> listeners;
public MVCController() {
model = new MVCModel();
listeners = new ArrayList<ChangeListener>();
}
public void update(String input) {
model.setInputs(input);
for (ChangeListener l : listeners) {
l.stateChanged(new ChangeEvent(this));
}
}
public void attach(ChangeListener c) {
listeners.add(c);
}
}
class MVCModel {
private ArrayList<String> inputs;
MVCModel() {
inputs = new ArrayList<String>();
}
public ArrayList<String> getInputs() {
return inputs;
}
public void setInputs(String input) {
inputs.add(input);
}
}
class MVCViews implements ChangeListener {
private JTextField input;
private JTextArea echo;
private ArrayList<String> toPrint = new ArrayList<String>();
MVCController controller;
MVCViews(final MVCController controller) {
// !! controller = new MVCController();
this.controller = controller;
JPanel myPanel = new JPanel();
JButton addButton = new JButton("add");
echo = new JTextArea(10, 20);
echo.append("Hello there! \n");
echo.append("Type something below!\n");
myPanel.setLayout(new BorderLayout());
myPanel.add(addButton, BorderLayout.NORTH);
input = new JTextField();
final JFrame frame = new JFrame();
frame.add(myPanel, BorderLayout.NORTH);
frame.add(echo, BorderLayout.CENTER);
frame.add(input, BorderLayout.SOUTH);
addButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (controller != null) {
controller.update(input.getText());
}
}
});
frame.pack();
frame.setVisible(true);
}
public void setController(MVCController controller) {
this.controller = controller;
}
#Override
public void stateChanged(ChangeEvent e) {
if (controller != null) {
toPrint = controller.model.getInputs();
for (String s : toPrint) {
echo.append(s + "\n");
}
}
}
}

Using a single JTextArea with multiple UndoManagers

I have a JTextArea and a JComboBox to allow me to cycle through various open files - the contents of the JTextArea change as I select a different file. I am trying to maintain a different Undo buffer per file and have defined a separate UndoManager per file.
I have created a simpler SSCCE to demonstrate my problem using two buffers, which I call "One" and "Two" - with a simple button to switch between them. Once an UndoableEdit happens, it checks the active buffer and performs an addEdit() on the respective UndoManager. When the "Undo" button is pressed, then it checks canUndo() and performs an undo() on the respective UndoManager. I have a flag called ignoreEdit, which is used when switching between buffers to ignore those edits from being recorded.
If I never switch between the buffers, then I don't have a problem, Undo works as expected. It is only when I switch between the buffers and appear to "break" the Document, does it fail. The following steps can be used to recreate the problem:
In buffer "One", type:
THIS
IS ONE
EXAMPLE
Switch to buffer "Two", type:
THIS
IS ANOTHER
EXAMPLE
Switch to buffer "One" and press the "Undo" button multiple times. After a few Undo operations, the buffer looks like this (with no way for the cursor to select the first two lines). However, the contents of textArea.getText() are correct as per the System.out.println() - so, it looks like a rendering issue?
THIS
THISIS ONE
This can't be the first time that someone has tried to implement independent Undo buffers per file? I am obviously doing something wrong with the Document model and inherently breaking it, but I looking for some advice on how best to fix this?
The code for the SSCCE is included below:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.undo.*;
public class SSCCE extends JFrame implements ActionListener, UndoableEditListener {
private final JLabel labTextArea;
private final JTextArea textArea;
private final JScrollPane scrollTextArea;
private final Document docTextArea;
private final JButton bOne, bTwo, bUndo;
private final UndoManager uOne, uTwo;
private String sOne, sTwo;
private boolean ignoreEdit = false;
public SSCCE(String[] args) {
setTitle("SSCCE - Short, Self Contained, Correct Example");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(300, 200);
setLocationRelativeTo(null);
labTextArea = new JLabel("One");
getContentPane().add(labTextArea, BorderLayout.PAGE_START);
uOne = new UndoManager();
uTwo = new UndoManager();
sOne = new String();
sTwo = new String();
textArea = new JTextArea();
docTextArea = textArea.getDocument();
docTextArea.addUndoableEditListener(this);
scrollTextArea = new JScrollPane(textArea);
getContentPane().add(scrollTextArea, BorderLayout.CENTER);
JPanel pButtons = new JPanel();
bOne = new JButton("One");
bOne.addActionListener(this);
bOne.setFocusable(false);
pButtons.add(bOne, BorderLayout.LINE_START);
bTwo = new JButton("Two");
bTwo.addActionListener(this);
bTwo.setFocusable(false);
pButtons.add(bTwo, BorderLayout.LINE_END);
bUndo = new JButton("Undo");
bUndo.addActionListener(this);
bUndo.setFocusable(false);
pButtons.add(bUndo, BorderLayout.LINE_END);
getContentPane().add(pButtons, BorderLayout.PAGE_END);
setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(bOne)) {
if (!labTextArea.getText().equals("One")) {
sTwo = textArea.getText();
ignoreEdit = true;
textArea.setText(sOne);
ignoreEdit = false;
labTextArea.setText("One");
}
}
else if (e.getSource().equals(bTwo)) {
if (!labTextArea.getText().equals("Two")) {
sOne = textArea.getText();
ignoreEdit = true;
textArea.setText(sTwo);
ignoreEdit = false;
labTextArea.setText("Two");
}
}
else if (e.getSource().equals(bUndo)) {
if (labTextArea.getText().equals("One")) {
try {
if (uOne.canUndo()) {
System.out.println("Performing Undo for One");
uOne.undo();
System.out.println("Buffer One is now:\n" + textArea.getText() + "\n");
}
else {
System.out.println("Nothing to Undo for One");
}
}
catch (CannotUndoException ex) {
ex.printStackTrace();
}
}
else if (labTextArea.getText().equals("Two")) {
try {
if (uTwo.canUndo()) {
System.out.println("Performing Undo for Two");
uTwo.undo();
System.out.println("Buffer Two is now:\n" + textArea.getText() + "\n");
}
else {
System.out.println("Nothing to Undo for Two");
}
}
catch (CannotUndoException ex) {
ex.printStackTrace();
}
}
}
}
#Override
public void undoableEditHappened(UndoableEditEvent e) {
if (!ignoreEdit) {
if (labTextArea.getText().equals("One")) {
System.out.println("Adding Edit for One");
uOne.addEdit(e.getEdit());
}
else if (labTextArea.getText().equals("Two")) {
System.out.println("Adding Edit for Two");
uTwo.addEdit(e.getEdit());
}
}
}
public static void main(final String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new SSCCE(args);
}
});
}
}

Previously I had attempted to create a new instance of the Document class (each referencing the same Undo listener) and was going to use JTextArea.setDocument() instead of JTextArea.setText(). However, Document is an interface and can't be instantiated, but after reading the reference that mKorbel posted, I tried this using the PlainDocument class instead, which worked.
I have decided to maintain a HashMap<String, Document> to contain my Document classes and switch between them. When I switch the Document, I don't see the Undo/Redo issue - I suppose as I am no longer breaking the Document.
Updated SSCCE below which now uses JTextArea.setDocument() instead of JTextArea.setText(). This also has the advantage of not requiring the ignoreEdit boolean as setDocument() doesn't trigger an UndoableEditEvent, whereas setText() does. Each Document then references the local classes UndoableEditListener.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;
import javax.swing.undo.*;
public class SSCCE extends JFrame implements ActionListener, UndoableEditListener {
private final JLabel labTextArea;
private final JTextArea textArea;
private final JScrollPane scrollTextArea;
private final Document docTextArea;
private final JButton bOne, bTwo, bUndo;
private final UndoManager uOne, uTwo;
private Document dOne, dTwo;
public SSCCE(String[] args) {
setTitle("SSCCE - Short, Self Contained, Correct Example");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(300, 200);
setLocationRelativeTo(null);
labTextArea = new JLabel("One");
getContentPane().add(labTextArea, BorderLayout.PAGE_START);
uOne = new UndoManager();
uTwo = new UndoManager();
dOne = new PlainDocument();
dTwo = new PlainDocument();
dOne.addUndoableEditListener(this);
dTwo.addUndoableEditListener(this);
textArea = new JTextArea();
docTextArea = textArea.getDocument();
docTextArea.addUndoableEditListener(this);
textArea.setDocument(dOne);
scrollTextArea = new JScrollPane(textArea);
getContentPane().add(scrollTextArea, BorderLayout.CENTER);
JPanel pButtons = new JPanel();
bOne = new JButton("One");
bOne.addActionListener(this);
bOne.setFocusable(false);
pButtons.add(bOne, BorderLayout.LINE_START);
bTwo = new JButton("Two");
bTwo.addActionListener(this);
bTwo.setFocusable(false);
pButtons.add(bTwo, BorderLayout.LINE_END);
bUndo = new JButton("Undo");
bUndo.addActionListener(this);
bUndo.setFocusable(false);
pButtons.add(bUndo, BorderLayout.LINE_END);
getContentPane().add(pButtons, BorderLayout.PAGE_END);
setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(bOne)) {
if (!labTextArea.getText().equals("One")) {
textArea.setDocument(dOne);
labTextArea.setText("One");
}
}
else if (e.getSource().equals(bTwo)) {
if (!labTextArea.getText().equals("Two")) {
textArea.setDocument(dTwo);
labTextArea.setText("Two");
}
}
else if (e.getSource().equals(bUndo)) {
if (labTextArea.getText().equals("One")) {
try {
if (uOne.canUndo()) {
System.out.println("Performing Undo for One");
uOne.undo();
System.out.println("Buffer One is now:\n" + textArea.getText() + "\n");
}
else {
System.out.println("Nothing to Undo for One");
}
}
catch (CannotUndoException ex) {
ex.printStackTrace();
}
}
else if (labTextArea.getText().equals("Two")) {
try {
if (uTwo.canUndo()) {
System.out.println("Performing Undo for Two");
uTwo.undo();
System.out.println("Buffer Two is now:\n" + textArea.getText() + "\n");
}
else {
System.out.println("Nothing to Undo for Two");
}
}
catch (CannotUndoException ex) {
ex.printStackTrace();
}
}
}
}
#Override
public void undoableEditHappened(UndoableEditEvent e) {
if (labTextArea.getText().equals("One")) {
System.out.println("Adding Edit for One");
uOne.addEdit(e.getEdit());
}
else if (labTextArea.getText().equals("Two")) {
System.out.println("Adding Edit for Two");
uTwo.addEdit(e.getEdit());
}
}
public static void main(final String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new SSCCE(args);
}
});
}
}

This is not an answer per se, but a demonstration of a different way of approaching the same problem.
What this does is wraps the UndoableEditListener in a self managed proxy, which has it's own UndoManager and Document.
Tested this with Java 7 and Java 8:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.UndoableEditEvent;
import javax.swing.event.UndoableEditListener;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import javax.swing.text.PlainDocument;
import javax.swing.undo.UndoManager;
public class UndoExample {
public static void main(String[] args) {
new UndoExample();
}
private int index = 0;
private Map<String, Undoer> mapUndoers;
private JTextArea ta;
private Undoer current;
public UndoExample() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
mapUndoers = new HashMap<>(2);
mapUndoers.put("One", new Undoer());
mapUndoers.put("Two", new Undoer());
ta = new JTextArea(4, 20);
ta.setWrapStyleWord(true);
ta.setLineWrap(true);
JButton btnOne = new JButton("One");
JButton btnTwo = new JButton("Two");
ActionListener al = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
install(e.getActionCommand());
}
};
btnOne.addActionListener(al);
btnTwo.addActionListener(al);
JButton undo = new JButton("Undo");
undo.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (current != null) {
current.undo();
}
}
});
JPanel panel = new JPanel(new GridBagLayout());
panel.add(btnOne);
panel.add(btnTwo);
panel.add(undo);
install("One");
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(ta));
frame.add(panel, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected void install(String name) {
Undoer undoer = mapUndoers.get(name);
if (undoer != null) {
current = undoer;
undoer.install(ta);
}
}
public class Undoer implements UndoableEditListener {
private UndoManager undoManager;
private Document doc;
public Undoer() {
undoManager = new UndoManager();
doc = createDocument();
doc.addUndoableEditListener(this);
}
public void undo() {
undoManager.undo();
}
public void undoOrRedo() {
undoManager.undoOrRedo();
}
protected Document createDocument() {
return new PlainDocument();
}
public void install(JTextComponent comp) {
comp.setDocument(doc);
}
#Override
public void undoableEditHappened(UndoableEditEvent e) {
undoManager.addEdit(e.getEdit());
}
}
}

how to drag and drop files from a directory in java

I want to implement dragging and dropping of files from a directory such as someones hard drive but can't figure out how to do it. I've read the java api but it talks of color pickers and dragging and dropping between lists but how to drag files from a computers file system and drop into my application. I tried writing the transferhandler class and a mouse event for when the drag starts but nothing seems to work. Now I'm back to just having my JFileChooser set so drag has been enabled but how to drop?
Any info or point in the right direction greatly appreciated.
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.BorderFactory;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.filechooser.FileFilter;
public class FileChooserDemo
extends JPanel
implements ActionListener
{
JLabel selectedFileLabel;
JList selectedFilesList;
JLabel returnCodeLabel;
public FileChooserDemo()
{
super();
createContent();
}
void initFrameContent()
{
JPanel closePanel = new JPanel();
add(closePanel, BorderLayout.SOUTH);
}
private void createContent()
{
setLayout(new BorderLayout());
JPanel NorthPanel = new JPanel();
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("File");
JMenuItem quit = new JMenuItem("Quit");
menuBar.add(menu);
menu.add(quit);
NorthPanel.add(menu,BorderLayout.NORTH);
JPanel buttonPanel = new JPanel(new GridLayout(7,1 ));
JButton openButton = new JButton("Open...");
openButton.setActionCommand("OPEN");
openButton.addActionListener(this);
buttonPanel.add(openButton);
JButton saveButton = new JButton("Save...");
saveButton.setActionCommand("SAVE");
saveButton.addActionListener(this);
buttonPanel.add(saveButton);
JButton delete = new JButton("Delete");
delete.addActionListener(this);
delete.setActionCommand("DELETE");
buttonPanel.add(delete);
add(buttonPanel, BorderLayout.WEST);
// create a panel to display the selected file(s) and the return code
JPanel displayPanel = new JPanel(new BorderLayout());
selectedFileLabel = new JLabel("-");
selectedFileLabel.setBorder(BorderFactory.createTitledBorder
("Selected File/Directory "));
displayPanel.add(selectedFileLabel, BorderLayout.NORTH);
selectedFilesList = new JList();
JScrollPane sp = new JScrollPane(selectedFilesList);
sp.setBorder(BorderFactory.createTitledBorder("Selected Files "));
MouseListener listener = new MouseAdapter()
{
public void mousePressed(MouseEvent me)
{
JComponent comp = (JComponent) me.getSource();
TransferHandler handler = comp.getTransferHandler();
handler.exportAsDrag(comp, me, TransferHandler.MOVE);
}
};
selectedFilesList.addMouseListener(listener);
displayPanel.add(sp);
returnCodeLabel = new JLabel("");
returnCodeLabel.setBorder(BorderFactory.createTitledBorder("Return Code"));
displayPanel.add(returnCodeLabel, BorderLayout.SOUTH);
add(displayPanel);
}
public void actionPerformed(ActionEvent e)
{
int option = 0;
File selectedFile = null;
File[] selectedFiles = new File[0];
if (e.getActionCommand().equals("CLOSE"))
{
System.exit(0);
}
else if (e.getActionCommand().equals("OPEN"))
{
JFileChooser chooser = new JFileChooser();
chooser.setDragEnabled(true);
chooser.setMultiSelectionEnabled(true);
option = chooser.showOpenDialog(this);
selectedFiles = chooser.getSelectedFiles();
}
else if (e.getActionCommand().equals("SAVE"))
{
JFileChooser chooser = new JFileChooser();
option = chooser.showSaveDialog(this);
selectedFiles = chooser.getSelectedFiles();
}
// display the selection and return code
if (selectedFile != null)
selectedFileLabel.setText(selectedFile.toString());
else
selectedFileLabel.setText("null");
DefaultListModel listModel = new DefaultListModel();
for (int i =0; i < selectedFiles.length; i++)
listModel.addElement(selectedFiles[i]);
selectedFilesList.setModel(listModel);
returnCodeLabel.setText(Integer.toString(option));
}
public static void main(String[] args)
{
SwingUtilities.invokeLater
(new Runnable()
{
public void run()
{
FileChooserDemo app = new FileChooserDemo();
app.initFrameContent();
JFrame frame = new JFrame("LoquetUP");
frame.getContentPane().add(app);
frame.setDefaultCloseOperation(3);
frame.setSize(600,400);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
//frame.pack();
frame.setVisible(true);
}
});
}
}

This is my take on the idea. I've used the "traditional" drag and drop API in this example. It has some extra "paint" tweaks just to show off what you might be able to do.
This example doesn't scan folders dropped onto it, so any folder will only register as a single file, but I'm sure you can work it out
public class TestDragNDropFiles {
public static void main(String[] args) {
new TestDragNDropFiles();
}
public TestDragNDropFiles() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new DropPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class DropPane extends JPanel {
private DropTarget dropTarget;
private DropTargetHandler dropTargetHandler;
private Point dragPoint;
private boolean dragOver = false;
private BufferedImage target;
private JLabel message;
public DropPane() {
try {
target = ImageIO.read(new File("target.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
setLayout(new GridBagLayout());
message = new JLabel();
message.setFont(message.getFont().deriveFont(Font.BOLD, 24));
add(message);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
protected DropTarget getMyDropTarget() {
if (dropTarget == null) {
dropTarget = new DropTarget(this, DnDConstants.ACTION_COPY_OR_MOVE, null);
}
return dropTarget;
}
protected DropTargetHandler getDropTargetHandler() {
if (dropTargetHandler == null) {
dropTargetHandler = new DropTargetHandler();
}
return dropTargetHandler;
}
#Override
public void addNotify() {
super.addNotify();
try {
getMyDropTarget().addDropTargetListener(getDropTargetHandler());
} catch (TooManyListenersException ex) {
ex.printStackTrace();
}
}
#Override
public void removeNotify() {
super.removeNotify();
getMyDropTarget().removeDropTargetListener(getDropTargetHandler());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (dragOver) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(new Color(0, 255, 0, 64));
g2d.fill(new Rectangle(getWidth(), getHeight()));
if (dragPoint != null && target != null) {
int x = dragPoint.x - 12;
int y = dragPoint.y - 12;
g2d.drawImage(target, x, y, this);
}
g2d.dispose();
}
}
protected void importFiles(final List files) {
Runnable run = new Runnable() {
#Override
public void run() {
message.setText("You dropped " + files.size() + " files");
}
};
SwingUtilities.invokeLater(run);
}
protected class DropTargetHandler implements DropTargetListener {
protected void processDrag(DropTargetDragEvent dtde) {
if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
dtde.acceptDrag(DnDConstants.ACTION_COPY);
} else {
dtde.rejectDrag();
}
}
#Override
public void dragEnter(DropTargetDragEvent dtde) {
processDrag(dtde);
SwingUtilities.invokeLater(new DragUpdate(true, dtde.getLocation()));
repaint();
}
#Override
public void dragOver(DropTargetDragEvent dtde) {
processDrag(dtde);
SwingUtilities.invokeLater(new DragUpdate(true, dtde.getLocation()));
repaint();
}
#Override
public void dropActionChanged(DropTargetDragEvent dtde) {
}
#Override
public void dragExit(DropTargetEvent dte) {
SwingUtilities.invokeLater(new DragUpdate(false, null));
repaint();
}
#Override
public void drop(DropTargetDropEvent dtde) {
SwingUtilities.invokeLater(new DragUpdate(false, null));
Transferable transferable = dtde.getTransferable();
if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
dtde.acceptDrop(dtde.getDropAction());
try {
List transferData = (List) transferable.getTransferData(DataFlavor.javaFileListFlavor);
if (transferData != null && transferData.size() > 0) {
importFiles(transferData);
dtde.dropComplete(true);
}
} catch (Exception ex) {
ex.printStackTrace();
}
} else {
dtde.rejectDrop();
}
}
}
public class DragUpdate implements Runnable {
private boolean dragOver;
private Point dragPoint;
public DragUpdate(boolean dragOver, Point dragPoint) {
this.dragOver = dragOver;
this.dragPoint = dragPoint;
}
#Override
public void run() {
DropPane.this.dragOver = dragOver;
DropPane.this.dragPoint = dragPoint;
DropPane.this.repaint();
}
}
}
}

You need to experiment with Drag & Drop and see exactly what flavors are available when you try to drag files. If you do this in your custom TransferHandler you'll be pleasantly surprised one Flavor is the DataFlavor.javaFileListFlavor, which indicates that the item can be used simply as a List. Try it and you'll see that it works!
Note on review of your posted code, I don't see any code for your attempt at using a TransferHandler, so it is hard to say what you could be doing wrong here.
Edit 1
You seem to be trying to use a MouseListener for your drag and drop, and I'm not familiar with this usage. Can you show a reference to a tutorial that tells you to do this?
Edit 2
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.swing.*;
#SuppressWarnings("serial")
public class FileDragDemo extends JPanel {
private JList list = new JList();
public FileDragDemo() {
list.setDragEnabled(true);
list.setTransferHandler(new FileListTransferHandler(list));
add(new JScrollPane(list));
}
private static void createAndShowGui() {
FileDragDemo mainPanel = new FileDragDemo();
JFrame frame = new JFrame("FileDragDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
#SuppressWarnings("serial")
class FileListTransferHandler extends TransferHandler {
private JList list;
public FileListTransferHandler(JList list) {
this.list = list;
}
public int getSourceActions(JComponent c) {
return COPY_OR_MOVE;
}
public boolean canImport(TransferSupport ts) {
return ts.isDataFlavorSupported(DataFlavor.javaFileListFlavor);
}
public boolean importData(TransferSupport ts) {
try {
#SuppressWarnings("rawtypes")
List data = (List) ts.getTransferable().getTransferData(
DataFlavor.javaFileListFlavor);
if (data.size() < 1) {
return false;
}
DefaultListModel listModel = new DefaultListModel();
for (Object item : data) {
File file = (File) item;
listModel.addElement(file);
}
list.setModel(listModel);
return true;
} catch (UnsupportedFlavorException e) {
return false;
} catch (IOException e) {
return false;
}
}
}