Develop Reference

Unable to drag and drop sometimes

package newjframe;
import java.awt.BorderLayout;
import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.MouseEvent;
import javax.swing.JComponent;
import javax.swing.event.MouseInputAdapter;
public class NewJFrame extends javax.swing.JFrame {
public NewJFrame() {
initComponents();
setLocationRelativeTo(null);
}
public class Draggable extends JComponent {
private Point pointPressed;
private JComponent draggable;
public Draggable(final JComponent component, final int x, final int y) {
draggable = component;
setCursor(new Cursor(Cursor.HAND_CURSOR));
setLocation(x, y);
setSize(component.getPreferredSize());
setLayout(new BorderLayout());
add(component);
MouseInputAdapter mouseAdapter = new MouseHandler();
addMouseMotionListener(mouseAdapter);
addMouseListener(mouseAdapter);
}
public class MouseHandler extends MouseInputAdapter {
#Override
public void mouseDragged(final MouseEvent e) {
Point pointDragged = e.getPoint();
Point location = getLocation();
location.translate(pointDragged.x - pointPressed.x,
pointDragged.y - pointPressed.y);
setLocation(location);
}
#Override
public void mousePressed(final MouseEvent e) {
pointPressed = e.getPoint();
}
}
}
#SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
panel = new javax.swing.JPanel();
layer = new javax.swing.JLayeredPane();
cbb = new javax.swing.JComboBox<>();
label = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
cbb.setModel(new javax.swing.DefaultComboBoxModel<>(new String[] { "Item 1", "Item 2", "Item 3"}));
cbb.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
cbbActionPerformed(evt);
}
});
layer.setLayer(cbb, javax.swing.JLayeredPane.DEFAULT_LAYER);
layer.setLayer(label, javax.swing.JLayeredPane.DEFAULT_LAYER);
javax.swing.GroupLayout layerLayout = new javax.swing.GroupLayout(layer);
layer.setLayout(layerLayout);
layerLayout.setHorizontalGroup(
layerLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layerLayout.createSequentialGroup()
.addGap(41, 41, 41)
.addComponent(cbb, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(129, 129, 129)
.addComponent(label)
.addContainerGap(202, Short.MAX_VALUE))
);
layerLayout.setVerticalGroup(
layerLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layerLayout.createSequentialGroup()
.addGap(30, 30, 30)
.addGroup(layerLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(label)
.addComponent(cbb, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(329, Short.MAX_VALUE))
);
javax.swing.GroupLayout panelLayout = new javax.swing.GroupLayout(panel);
panel.setLayout(panelLayout);
panelLayout.setHorizontalGroup(
panelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(layer)
);
panelLayout.setVerticalGroup(
panelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(layer)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(panel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(panel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
private void cbbActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
int[] xy = {100, 200, 300};
label.setText("DRAG THIS");
switch (cbb.getSelectedIndex()) {
case 0:
draglabel = new Draggable(label, xy[0], xy[0]);
layer.add(draglabel);
break;
case 1:
draglabel = new Draggable(label, xy[0], xy[1]);
layer.add(draglabel);
break;
case 2:
draglabel = new Draggable(label, xy[0], xy[2]);
layer.add(draglabel);
break;
default:
draglabel = new Draggable(label, xy[0], xy[0]);
layer.add(draglabel);
}
}
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JComboBox<String> cbb;
private javax.swing.JLabel label;
private javax.swing.JLayeredPane layer;
private javax.swing.JPanel panel;
// End of variables declaration
Draggable draglabel;
}
The above code should allow the Jlabels to be dragged and dropped with ease, but every time they're called with the actionlistener in JComboBox, they become harder to drag and drop. GIF added to for better clarity https://imgur.com/rPL5ZMC I have tried repaint() method in the class method, and actionlistner but it didn't work

Again, I would tend to simplify try to clarify things, including:
Use the much simpler MouseListener/MouseAdapter and not D&D as you initially were doing. You appear to have made this change.
Not wrapping the JLabel unnecessarily in another component
Thus the Mouse listeners would be added directly on the JLabel and not on a wrapper object.
Not changing the JLayeredPane's default and unique layout
Explicitly removing the old components before adding new ones
Calling repaint() on the JLayeredPane after adding or removing components.
For example, something like this:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class TestDragging extends JPanel {
private static final String[] ITEMS = {"Item One", "Item Two", "Item Three"};
private static final Dimension PREF_SIZE = new Dimension(400, 400);
private JLabel label;
private JComboBox<String> comboBox = new JComboBox<>(ITEMS);
private JLayeredPane layeredPane = new JLayeredPane();
public TestDragging() {
comboBox.addActionListener(new ComboListener());
JPanel topPanel = new JPanel();
topPanel.add(comboBox);
layeredPane.setPreferredSize(PREF_SIZE);
layeredPane.setBorder(BorderFactory.createEtchedBorder());
setLayout(new BorderLayout());
add(topPanel, BorderLayout.PAGE_START);
add(layeredPane, BorderLayout.CENTER);
}
private class ComboListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
if (label != null) {
layeredPane.remove(label);
}
int index = comboBox.getSelectedIndex();
int x = 100;
int y = 100 + 100 * index;
String text = comboBox.getSelectedItem().toString();
label = createDraggingLabel(x, y, text);
layeredPane.add(label, JLayeredPane.DEFAULT_LAYER);
layeredPane.repaint();
}
private JLabel createDraggingLabel(int x, int y, String text) {
JLabel label = new JLabel(text);
label.setSize(label.getPreferredSize());
label.setLocation(x, y);
MyMouse myMouse = new MyMouse();
label.addMouseListener(myMouse);
label.addMouseMotionListener(myMouse);
return label;
}
}
private static void createAndShowGui() {
TestDragging mainPanel = new TestDragging();
JFrame frame = new JFrame("Test Dragging");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
class MyMouse extends MouseAdapter {
private Point pointPressed = null;
#Override
public void mousePressed(MouseEvent e) {
pointPressed = e.getPoint();
}
#Override
public void mouseDragged(MouseEvent e) {
JLabel label = (JLabel) e.getSource();
label.setCursor(new Cursor(Cursor.HAND_CURSOR));
Point pointDragged = e.getPoint();
Point location = label.getLocation();
int dx = pointDragged.x - pointPressed.x;
int dy = pointDragged.y - pointPressed.y;
location.translate(dx, dy);
label.setLocation(location);
Container container = label.getParent();
container.repaint();
}
}

I've called and instantiated the drag n drop function in the constructor then I've used label.setLocation(x, y) to solve this problem since the JComboBox merely determines the position of the labels, I do not need to have re-instantiate the object every time actionperformed is called.

How can I display an image in a JPanel

My question here is how can I display an image into a JPanel? Other topics here asking something similar aren't clear to my about how can I do that.
I have a directory in my project folder that have image files Project Folder/GUI/img, specifically gray.png and green.png which I want to display in a JPanel.
I tried with the following code using ImageIcon and JLabel that I found in other post:
ImageIcon image = new ImageIcon("GUI/img/gray.png");
JLabel label = new JLabel(image);
//JPanel panel is already initialized by the IDE
panel.add(label)
But doesn't work... The JPanel remain empty without displaying any image. How can I do that?
Additional to this, I want that the image inside the JPanel change (gray.png for green.png) when some action is performed, for example pressing a button. I can archive that by the same method for display the image in the JPanel right?
Thanks in advance!
EDIT: Here's an example of a test code for get this. The initialization is done automatically by the IDE.
import java.awt.Image;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
public class Sample extends javax.swing.JFrame {
public Sample() {
initComponents();
}
//Initialization
private void initComponents() {
PanelImage = new javax.swing.JPanel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowOpened(java.awt.event.WindowEvent evt) {
formWindowOpened(evt);
}
});
javax.swing.GroupLayout PanelImageLayout = new javax.swing.GroupLayout(PanelImage);
PanelImage.setLayout(PanelImageLayout);
PanelImageLayout.setHorizontalGroup(
PanelImageLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 100, Short.MAX_VALUE)
);
PanelImageLayout.setVerticalGroup(
PanelImageLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 100, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(61, 61, 61)
.addComponent(PanelImage, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(239, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(45, 45, 45)
.addComponent(PanelImage, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(155, Short.MAX_VALUE))
);
pack();
}
private void formWindowOpened(java.awt.event.WindowEvent evt) {
try {
DisplayImage(PanelImage, "/GUI/img/gray.png");
} catch (Exception ex) {
Logger.getLogger(Sample.class.getName()).log(Level.SEVERE, null, ex);
}
}
//For display the url image in a JPanel
private void DisplayImage(JPanel jp, String url) throws IOException, Exception {
try {
Image image=ImageIO.read(this.getClass().getResource(url));
ImageIcon imageicon=new ImageIcon(image);
JLabel label=new JLabel(imageicon);
jp.add(label);
} catch (IOException ex) {
throw new IOException();
} catch (Exception ex) {
throw new Exception();
}
}
public static void main(String args[]) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Sample.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Sample().setVisible(true);
}
});
}
// Variables declaration
private javax.swing.JPanel PanelImage;
}
The private void DisplayImage(JPanel jp, String url) is what I need to work for display the image, from the url String url in the JPanel jp

Looking for pieces of code in Google I ended up with a solution... And was applying the same pattern that previous comments refer.
The code that gave me the solution was:
label.setIcon(new javax.swing.ImageIcon(getClass().getResource("/resources/gray.png")))
With that, I made then the method that I wanted to implement:
private static void DisplayImage(JPanel jp, String url) {
JLabel jl=new JLabel();
jl.setIcon(new javax.swing.ImageIcon(getClass().getResource(url)));
jp.add(jl);
}
Maybe this is not the perfect and most-correct solution, but works perfect to my, that is what I want.
Thanks all for the answers and suggestions!

I had a similar issue when I was working on creating Minesweeper. I ended up finding a solution and getting it to work by first loading an Image and then creating an ImageIcon from that Image.
Image myImage = ImageIO.read(getClass().getResource("image_path.jpg"));
myImage = myImage.getScaledInstance(30, 30, java.awt.Image.SCALE_SMOOTH);
ImageIcon myImageIcon = new ImageIcon(myImage);

you have to use ImageIcon(this.getClass().getResource("/Gui/img/gray.png"));
here is example its working.
import java.awt.Dimension;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class ExImage extends JPanel
{
public ExImage()
{
ImageIcon imageIcon = new ImageIcon(this.getClass().getResource("/gray.png"));
JLabel label = new JLabel(imageIcon);
add(label);
}
public static void main(String[] args)
{
JFrame frame = new JFrame();
frame.add(new ExImage());
frame.setVisible(true);
frame.setPreferredSize(new Dimension(200, 300));
}
}

JScrollPane and autoscroll: Disturbing scrolling behavior

I am writing an application which uses a JScrollPane. In this JScrollPane I want to automatically display search results, This means, that I have to dynamically add and remove the results within the JScrollPane. The results are realised as JTextArea, which are embeded within a GridBagLayout.
When there is a high number of search results, the JScrollPane automatically scrolls to the bottom (It should be at the top). I have solved it with a solution I found here. The problem hereby is, that you can see, how it scrolls back to the top. Is it possible to remove this behaviour?
The following things I found out:
I have to remove the previous search results to display the new ones. If I don't remove the previous ones, it displays correctly.
It neither solves the prblem wgeb I update the JScrollPane every tune after adding arow nor when updating only after adding all rows.
The best would be to just disable autoscroll. I have created an executable example to demonstrate this behavior. When clicking the button "Add Row", 500 rows are added. When clicking it several times, it becomes very clear.
Thank you very much for your help!
import java.awt.GridBagConstraints;
import javax.swing.JTextArea;
public class ScrollPaneTest extends javax.swing.JFrame {
private javax.swing.JButton jButton1;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JScrollPane jScrollPane1;
/**
* Creates new form ScrollPaneTest
*/
public ScrollPaneTest() {
initComponents();
}
/**
* Adds a new row.
* #param index The index of the new row.
*/
private void addRow(int index) {
JTextArea row = new JTextArea("Area " + index);
row.setEditable(false);
row.setBorder(null);
GridBagConstraints gridBagConstraints = new GridBagConstraints();
gridBagConstraints.gridx = 0;
gridBagConstraints.gridy = index;
gridBagConstraints.fill = GridBagConstraints.BOTH;
gridBagConstraints.weightx = 1.0;
gridBagConstraints.insets = new java.awt.Insets(2, 0, 2, 0);
jPanel2.add(row, gridBagConstraints);
}
/**
* Initializes the components.
*/
private void initComponents() {
jScrollPane1 = new javax.swing.JScrollPane();
jPanel1 = new javax.swing.JPanel();
jPanel2 = new javax.swing.JPanel();
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jScrollPane1.setHorizontalScrollBarPolicy(javax.swing.ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
jScrollPane1.setVerticalScrollBarPolicy(javax.swing.ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
jScrollPane1.setPreferredSize(new java.awt.Dimension(400, 400));
jScrollPane1.setViewportView(jPanel1);
jPanel1.setLayout(new java.awt.BorderLayout());
jPanel2.setLayout(new java.awt.GridBagLayout());
jPanel1.add(jPanel2, java.awt.BorderLayout.NORTH);
jScrollPane1.setViewportView(jPanel1);
jButton1.setText("Create Rows");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addGap(148, 148, 148)
.addComponent(jButton1)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 245, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jButton1)
.addGap(0, 21, Short.MAX_VALUE))
);
pack();
}
/**
* Creates 500 new rows.
* #param evt
*/
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
jPanel2.removeAll();
for(int i = 0; i < 1000; i++) {
addRow(i);
}
javax.swing.SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
jScrollPane1.getVerticalScrollBar().setValue(0);
}
});
jPanel2.validate();
jPanel2.repaint();
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ScrollPaneTest().setVisible(true);
}
});
}
}
UPDATE 1
I removed the lambda expressions. Hopefully it should be now compileable also with < Java 8.
UPDATE 2
The problem with the disturbing scrolling behavior has been solved by replacing
jPanel2.validate();
jPanel2.repaint();
with
jScrollPane1.validate();
jScrollPane1.repaint();
Nevertheless, both answers to this question can be very helpful in some other cases and should be given attention.

One way to achieve this is to have a custom JViewPort for your scrollpane. This custom viewport overrides setViewPosition and uses a flag to prevent the scroll, or not.
Here is an example of such code, before changing the content of the textarea, we "lock" the viewport to prevent scrolling, and we unlock it later:
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JViewport;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class TestNoScrolling {
private int lineCount = 0;
private LockableViewPort viewport;
private JTextArea ta;
private final class LockableViewPort extends JViewport {
private boolean locked = false;
#Override
public void setViewPosition(Point p) {
if (locked) {
return;
}
super.setViewPosition(p);
}
public boolean isLocked() {
return locked;
}
public void setLocked(boolean locked) {
this.locked = locked;
}
}
protected void initUI() {
JFrame frame = new JFrame("test");
ta = new JTextArea(5, 30);
JScrollPane scrollpane = new JScrollPane();
viewport = new LockableViewPort();
viewport.setView(ta);
scrollpane.setViewport(viewport);
frame.add(scrollpane);
frame.pack();
frame.setVisible(true);
Timer t = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
viewport.setLocked(true);
ta.append("Some new line " + lineCount++ + "\n");
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
viewport.setLocked(false);
}
});
}
});
t.setRepeats(true);
t.start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TestNoScrolling().initUI();
}
});
}
}

You could simply set the Caret position to the start position (0), for example...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class ScrollNoMore {
public static void main(String[] args) {
new ScrollNoMore ();
}
public ScrollNoMore () {
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 {
private JTextArea ta;
private JScrollPane sp;
private Random rnd = new Random();
private boolean initalised = false;
public TestPane() {
setLayout(new BorderLayout());
ta = new JTextArea(20, 40);
sp = new JScrollPane(ta);
add(sp);
Timer timer = new Timer(250, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
long value = rnd.nextLong();
ta.append(String.valueOf(value) + "\n");
if (!initalised) {
ta.setCaretPosition(0);
initalised = true;
}
}
});
timer.start();
}
}
}
This will only set it the first time the Timer runs, this means that if you move the Caret or scroll position for some reason, it won't "flick" back. You could set up a series of states where by if the user moved the current view, it didn't effect the scrolling, but could be reset as required.

Dragging a textarea

Code in Question:
textArea.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
posX = e.getX();
posY = e.getY();
}
});
textArea.addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent e) {
setLocation(e.getXOnScreen() - posX, e.getYOnScreen() - posY);
}
});
Background:
I have a JFrame, in that JFrame there is a JScrollPane, and in the JScrollPane there is a JTextArea called "textArea". This JTextArea take up the entire JFrame and the JFrame is undecorated. So to give some perspective, here is generally what the JFrame looks like...
When the mouse clicks within the JTextArea and moves, the entire window is dragged. Everything is setup to not be focus able for this work, it's meant to be an overlay.
Issue:
The code listed above works fine and the world is at peace. But once there is enough text for the vertical scroll bar to appear (There is no horizontal because of line wrapping), dragging the window becomes an issue. When you click and just begin to move, the JFrame instantly moves much higher on the screen. The lines in JTextArea, the higher it moves up when you try to move it. I assume that the get*OnScreen() methods are issue because it's all relevant to the JTextArea.
Class in Question:
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Main extends JFrame {
private JTextArea textArea;
private JScrollPane textAreaScroll;
private int posX = 0;
private int posY = 0;
public Main() {
initComponents();
initListeners();
for(int i = 0; i < 20; i++){
addLine(i+" Hello");
}
}
public void addLine(String line){
textArea.append("\n> "+line);
textArea.setCaretPosition(textArea.getDocument().getLength());
}
private void initListeners(){
textArea.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
posX = e.getX();
posY = e.getY();
}
});
textArea.addMouseMotionListener(new MouseAdapter() {
public void mouseDragged(MouseEvent e) {
setLocation(e.getXOnScreen() - posX, e.getYOnScreen() - posY);
}
});
}
private void initComponents() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (UnsupportedLookAndFeelException | ClassNotFoundException | InstantiationException | IllegalAccessException e) {}
textAreaScroll = new JScrollPane();
textArea = new JTextArea();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setUndecorated(true);
setAlwaysOnTop(true);
setAutoRequestFocus(false);
setBackground(new Color(130,210,255,130));
setFocusCycleRoot(false);
setFocusable(false);
setFocusableWindowState(false);
setName("main");
setOpacity(0.4f);
setResizable(false);
textAreaScroll.setBorder(null);
textAreaScroll.setFocusable(false);
textAreaScroll.setRequestFocusEnabled(false);
textArea.setEditable(false);
textArea.setBackground(new Color(0, 0, 0));
textArea.setColumns(20);
textArea.setFont(new Font("Consolas", 0, 14));
textArea.setForeground(new Color(255, 255, 255));
textArea.setLineWrap(true);
textArea.setRows(5);
textArea.setText("> Hello world!\n> another line!");
textArea.setBorder(null);
textArea.setFocusable(false);
textArea.setRequestFocusEnabled(false);
textAreaScroll.setViewportView(textArea);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(textAreaScroll, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(textAreaScroll, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 214, Short.MAX_VALUE)
);
pack();
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new Main().setVisible(true);
}
});
}
}

Well your diagnosis was absolutely spot on:
When you click and just begin to move, the JFrame instantly moves
much higher on the screen. The lines in JTextArea, the higher it moves
up when you try to move it. I assume that the get*OnScreen() methods
are issue because it's all relevant to the JTextArea.
So to resolve this use GlassPane of JFrame to attach MouseXXXListeners thus we can get correct co-ordinates when dragging, the main problem with this solution is glasspane will consume events that are meant for other components on JFrame, this can be overcome by redispatching the MouseEvents appropriately):
Create JPanel (this glassPane/JPanel will be transparent via setOpaque(false)), attach xxxAdapters here.
Create custom listener class to redispacth MouseEvents to the necessary components (as glasspane will consume all events to the JTextArea/JScollPane)
Set JPanel as GlassPane of your JFrame via JFrame#setGlassPane(..) .
set JFrame visible than set glassPane visible via setVisible(true) (this has been a Swing glitch for some time if you set it visible before the frame is visible it wont be shown).
Here is your fixed code:
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.MouseInputAdapter;
public class Main extends JFrame {
private JTextArea textArea;
private JScrollPane textAreaScroll;
private JPanel glassPane;//create variable for glasspane
public Main() {
initComponents();
initListeners();
for (int i = 0; i < 20; i++) {
addLine(i + " Hello");
}
}
public void addLine(String line) {
textArea.append("\n> " + line);
textArea.setCaretPosition(textArea.getDocument().getLength());
}
private void initListeners() {
GlassPaneListener gpl = new GlassPaneListener(textAreaScroll.getVerticalScrollBar(), this);
//add the adapters/listeners to the glasspane
glassPane.addMouseMotionListener(gpl);
glassPane.addMouseListener(gpl);
}
private void initComponents() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (UnsupportedLookAndFeelException | ClassNotFoundException | InstantiationException | IllegalAccessException e) {
}
textAreaScroll = new JScrollPane();
textArea = new JTextArea();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setUndecorated(true);
setAlwaysOnTop(true);
setAutoRequestFocus(false);
setBackground(new Color(130, 210, 255, 130));
setFocusCycleRoot(false);
setFocusable(false);
setFocusableWindowState(false);
setName("main");
setOpacity(0.4f);
setResizable(false);
textAreaScroll.setBorder(null);
textAreaScroll.setFocusable(false);
textAreaScroll.setRequestFocusEnabled(false);
textArea.setEditable(false);
textArea.setBackground(new Color(0, 0, 0));
textArea.setColumns(20);
textArea.setFont(new Font("Consolas", 0, 14));
textArea.setForeground(new Color(255, 255, 255));
textArea.setLineWrap(true);
textArea.setRows(5);
textArea.setText("> Hello world!\n> another line!");
textArea.setBorder(null);
textArea.setFocusable(false);
textArea.setRequestFocusEnabled(false);
textAreaScroll.setViewportView(textArea);
textAreaScroll.setPreferredSize(new Dimension(200, 200));
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(textAreaScroll, javax.swing.GroupLayout.DEFAULT_SIZE, 400, Short.MAX_VALUE));
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(textAreaScroll, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 214, Short.MAX_VALUE));
//create and make glasspane not opaque
glassPane = new JPanel();
glassPane.setOpaque(false);
//set glasspane as JFrame glassPane
setGlassPane(glassPane);
pack();
setVisible(true);//set JFrame visible
//glassPane can only be setVisible after JFrame is visible
glassPane.setVisible(true);
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Main();
}
});
}
}
class GlassPaneListener extends MouseInputAdapter {
private int posX = 0;
private int posY = 0;
Toolkit toolkit;
private final Container contentPane;
private final Component textAreaScroll;
private final Component glassPane;
private final JFrame frame;
private boolean wasClickOnInterestedComponent = false;
public GlassPaneListener(Component textAreaScroll, JFrame frame) {
toolkit = Toolkit.getDefaultToolkit();
this.textAreaScroll = textAreaScroll;
this.frame = frame;
this.glassPane = frame.getGlassPane();
this.contentPane = frame.getContentPane();
}
#Override
public void mouseDragged(MouseEvent e) {
if (!redispatchMouseEvent(e)) {
frame.setLocation(e.getXOnScreen() - posX, e.getYOnScreen() - posY);
}
}
#Override
public void mousePressed(MouseEvent e) {
if (!redispatchMouseEvent(e)) {//check if event was redispatched if not its meant for us :)
posX = e.getX();
posY = e.getY();
}
}
#Override
public void mouseReleased(MouseEvent me) {
wasClickOnInterestedComponent = false;
}
private boolean redispatchMouseEvent(MouseEvent e) {
Point glassPanePoint = e.getPoint();
Container container = contentPane;
Point containerPoint = SwingUtilities.convertPoint(glassPane, glassPanePoint, contentPane);
// The mouse event is probably over the content pane.
// Find out exactly which component it's over.
Component component = SwingUtilities.getDeepestComponentAt(container, containerPoint.x,
containerPoint.y);
if ((component != null) && (component.equals(textAreaScroll)) || wasClickOnInterestedComponent) {
wasClickOnInterestedComponent = true;//so that if we drag iur cursor off JScrollBar tghe window wont be moved
// Forward events over the scrollbar
Point componentPoint = SwingUtilities.convertPoint(glassPane, glassPanePoint, component);
component.dispatchEvent(new MouseEvent(component, e.getID(), e.getWhen(), e.getModifiers(),
componentPoint.x, componentPoint.y, e.getClickCount(), e.isPopupTrigger()));
return true;//the event was redispatched
} else {
return false;//event was not redispatched
}
}
}

You are saying JFrame instantly moves much higher on the screen. The lines in JTextArea but actually it is scrolled down so only last few lines are visible.
If you would like to see textArea content from top, change is here
initComponents();
initListeners();
for (int i = 0; i < 20; i++) {
addLine(i + " Hello");
}
//set scrolling position to top
textArea.setCaretPosition(0);

Browse for image file and display it using Java Swing

My problem here is,
after clicking Browse button it displays all files in a directory to choose,
then the chosen image is displayed in GUI correctly. But When i click Browse button
for the second time, it shows the old image only instead of showing the new one. Please help me in this.
For reference, i uploaded the UI.
package GUI;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Graphics2D;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
#SuppressWarnings("serial")
public class MainAppFrame extends JFrame {
private JPanel contentPane;
File targetFile;
BufferedImage targetImg;
public JPanel panel,panel_1;
private static final int baseSize = 128;
private static final String basePath =
"C:\\Documents and Settings\\Administrator\\Desktop\\Images";
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainAppFrame frame = new MainAppFrame();
frame.setVisible(true);
frame.setResizable(false);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public MainAppFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 550, 400);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(new BorderLayout(0, 0));
panel = new JPanel();
panel.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true));
contentPane.add(panel, BorderLayout.WEST);
JButton btnBrowse = new JButton("Browse");
btnBrowse.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
browseButtonActionPerformed(e);
}
});
JLabel lblSelectTargetPicture = new JLabel("Select target picture..");
JButton btnDetect = new JButton("Detect");
btnDetect.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
JButton btnAddDigit = new JButton("Add Digit");
btnAddDigit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
JButton button = new JButton("Recognize");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
panel_1 = new JPanel();
panel_1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true));
GroupLayout gl_panel = new GroupLayout(panel);
gl_panel.setHorizontalGroup(
gl_panel.createParallelGroup(Alignment.LEADING)
.addGroup(gl_panel.createSequentialGroup()
.addGap(6)
.addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
.addGroup(gl_panel.createSequentialGroup()
.addComponent(lblSelectTargetPicture)
.addGap(6)
.addComponent(btnBrowse))
.addGroup(gl_panel.createSequentialGroup()
.addGap(10)
.addComponent(btnDetect)
.addGap(18)
.addComponent(btnAddDigit))))
.addGroup(gl_panel.createSequentialGroup()
.addGap(50)
.addComponent(button))
.addGroup(gl_panel.createSequentialGroup()
.addContainerGap()
.addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 182, GroupLayout.PREFERRED_SIZE))
);
gl_panel.setVerticalGroup(
gl_panel.createParallelGroup(Alignment.LEADING)
.addGroup(gl_panel.createSequentialGroup()
.addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
.addGroup(gl_panel.createSequentialGroup()
.addGap(7)
.addComponent(lblSelectTargetPicture))
.addGroup(gl_panel.createSequentialGroup()
.addGap(3)
.addComponent(btnBrowse)))
.addGap(18)
.addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 199, GroupLayout.PREFERRED_SIZE)
.addGap(22)
.addGroup(gl_panel.createParallelGroup(Alignment.BASELINE)
.addComponent(btnDetect)
.addComponent(btnAddDigit))
.addGap(18)
.addComponent(button)
.addContainerGap())
);
panel.setLayout(gl_panel);
}
public BufferedImage rescale(BufferedImage originalImage)
{
BufferedImage resizedImage = new BufferedImage(baseSize, baseSize, BufferedImage.TYPE_INT_RGB);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, baseSize, baseSize, null);
g.dispose();
return resizedImage;
}
public void setTarget(File reference)
{
try {
targetFile = reference;
targetImg = rescale(ImageIO.read(reference));
} catch (IOException ex) {
Logger.getLogger(MainAppFrame.class.getName()).log(Level.SEVERE, null, ex);
}
panel_1.setLayout(new BorderLayout(0, 0));
panel_1.add(new JLabel(new ImageIcon(targetImg)));
setVisible(true);
}
private void browseButtonActionPerformed(java.awt.event.ActionEvent evt) {
JFileChooser fc = new JFileChooser(basePath);
fc.setFileFilter(new JPEGImageFileFilter());
int res = fc.showOpenDialog(null);
// We have an image!
try {
if (res == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
setTarget(file);
} // Oops!
else {
JOptionPane.showMessageDialog(null,
"You must select one image to be the reference.", "Aborting...",
JOptionPane.WARNING_MESSAGE);
}
} catch (Exception iOException) {
}
}
}
//JPEGImageFileFilter.java
package GUI;
import java.io.File;
import javax.swing.filechooser.FileFilter;
/*
* This class implements a generic file name filter that allows the listing/selection
* of JPEG files.
*/
public class JPEGImageFileFilter extends FileFilter implements java.io.FileFilter
{
public boolean accept(File f)
{
if (f.getName().toLowerCase().endsWith(".jpeg")) return true;
if (f.getName().toLowerCase().endsWith(".jpg")) return true;
if(f.isDirectory())return true;
return false;
}
public String getDescription()
{
return "JPEG files";
}
}

Each time a new image is selected, you're creating components unnecessarily and in error here:
public void setTarget(File reference) {
//....
panel_1.setLayout(new BorderLayout(0, 0));
panel_1.add(new JLabel(new ImageIcon(targetImg)));
setVisible(true);
Instead I would recommend that you have all these components created from the get-go, before any file/image has been selected, and then in this method, create an ImageIcon from the Image, and then simply use this Icon to set the Icon of an already existng JLabel rather than a new JLabel. This is done simply by calling myLabel.setIcon(new ImageIcon(targetImg));

Create an ImageViewer with method like ImageViewer.setImage(Image), display the image in a JLabel.
ImageViewer
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.util.Random;
public class ImageViewer {
JPanel gui;
/** Displays the image. */
JLabel imageCanvas;
/** Set the image as icon of the image canvas (display it). */
public void setImage(Image image) {
imageCanvas.setIcon(new ImageIcon(image));
}
public void initComponents() {
if (gui==null) {
gui = new JPanel(new BorderLayout());
gui.setBorder(new EmptyBorder(5,5,5,5));
imageCanvas = new JLabel();
JPanel imageCenter = new JPanel(new GridBagLayout());
imageCenter.add(imageCanvas);
JScrollPane imageScroll = new JScrollPane(imageCenter);
imageScroll.setPreferredSize(new Dimension(300,100));
gui.add(imageScroll, BorderLayout.CENTER);
}
}
public Container getGui() {
initComponents();
return gui;
}
public static Image getRandomImage(Random random) {
int w = 100 + random.nextInt(400);
int h = 50 + random.nextInt(200);
BufferedImage bi = new BufferedImage(
w,h,BufferedImage.TYPE_INT_RGB);
return bi;
}
public static void main(String[] args) throws Exception {
Runnable r = new Runnable() {
#Override
public void run() {
JFrame f = new JFrame("Image Viewer");
// TODO Fix kludge to kill the Timer
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final ImageViewer viewer = new ImageViewer();
f.setContentPane(viewer.getGui());
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);
ActionListener animate = new ActionListener() {
Random random = new Random();
#Override
public void actionPerformed(ActionEvent arg0) {
viewer.setImage(getRandomImage(random));
}
};
Timer timer = new Timer(1500,animate);
timer.start();
}
};
SwingUtilities.invokeLater(r);
}
}

I modified your code , I hope it will fulfill your requirement. I use MigLayout (it is a Layout manager) to arrange the component.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.BoxLayout;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import net.miginfocom.swing.MigLayout;
public class MyFileChooser
{
JFrame frame;
JPanel panel;
JButton btnBrowse;
JButton change;
JLabel imglabel;
File targetFile;
BufferedImage targetImg;
private static final int baseSize = 128;
private static final String basePath ="/images/fimage";
JPanel panel_1;
ImageIcon icon;
public MyFileChooser()
{
// TODO Auto-generated constructor stub
frame =new JFrame();
frame.setLayout(new MigLayout());
frame.setSize(300, 300);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel=new JPanel(new MigLayout());
panel_1 = new JPanel();
panel_1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(5, 5, 5), 1, true));
panel_1.setBackground(Color.pink);
btnBrowse=new JButton("browse");
btnBrowse.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
browseButtonActionPerformed(e);
}
});
change=new JButton("Delete");
change.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
changeButtonActionPerformed(e);
}
private void changeButtonActionPerformed(ActionEvent e)
{
// TODO Auto-generated method stub
imglabel.revalidate(); //ADD THIS AS WELL
imglabel.repaint(); //ADD THIS AS WELL
imglabel.setIcon(null);
System.out.println("delete button activated");
}
});
imglabel=new JLabel("Image");
imglabel.setSize(100, 100);
imglabel.setBackground(Color.yellow);
frame.add(panel_1,"span,pushx,pushy,growx,growy");
frame.add(btnBrowse);
frame.add(change,"");
//frame.pack();
}
protected void browseButtonActionPerformed(ActionEvent e)
{
JFileChooser fc = new JFileChooser(basePath);
fc.setFileFilter(new JPEGImageFileFilter());
int res = fc.showOpenDialog(null);
// We have an image!
try {
if (res == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
imglabel.setIcon(null);
setTarget(file);
} // Oops!
else {
JOptionPane.showMessageDialog(null,
"You must select one image to be the reference.", "Aborting...",
JOptionPane.WARNING_MESSAGE);
}
} catch (Exception iOException) {
}
}
public BufferedImage rescale(BufferedImage originalImage)
{
BufferedImage resizedImage = new BufferedImage(baseSize, baseSize, BufferedImage.TYPE_INT_RGB);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, baseSize, baseSize, null);
g.dispose();
return resizedImage;
}
public void setTarget(File reference)
{
try {
targetFile = reference;
targetImg = rescale(ImageIO.read(reference));
} catch (IOException ex) {
// Logger.getLogger(MainAppFrame.class.getName()).log(Level.SEVERE, null, ex);
}
panel_1.setLayout(new BorderLayout(0, 0));
icon=new ImageIcon(targetImg);
imglabel=new JLabel(icon);
panel_1.add(imglabel);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
new MyFileChooser();
}
});
}
}
JPEGImageFileFilter class , you can keep this class in same pakage
import java.io.File;
import javax.swing.filechooser.FileFilter;
public class JPEGImageFileFilter extends FileFilter implements FileFilter
{
public boolean accept(File f)
{
if (f.getName().toLowerCase().endsWith(".jpeg")) return true;
if (f.getName().toLowerCase().endsWith(".jpg")) return true;
if(f.isDirectory())return true;
return false;
}
public String getDescription()
{
return "JPEG files";
}
}