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Updating the Jlabel text by a loop in java Swing?

I want to update the Jlabel text in every second as long as the loop is running. how could I do this? I want to do as this fromat.
JPanel jpnl=new JPanel();
jfrm.add(jpnl);
String[] fonts=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames();
jlab = new JLabel("This is Label");
jpnl.add(jlab);
for(int i=0;i<fonts.length;i++){
System.out.println(fonts[i]);
jlab.setText(fonts[i]);
jlab.setFont(new Font(fonts[i],Font.PLAIN,30));
jlab.setForeground(Color.DARK_GRAY);
}

Swing's single threaded nature precludes using a loop or Thread.sleep in the way you seem to be trying. Doing so, will simply block the UI and prevent it from been painted/updated until the loop is completed.
Because Swing is not thread safe, you can't simply use another Thread and the above approaches to update the UI, without jumping through some hoops
The conical answer to your question is to use a Swing Timer, which triggers an update at a regular bases. Because these updates are triggered within the context of the Event Dispatching Thread, it makes it safe to use when you want to update the UI.
Take a closer look at How to use Swing Timers for more details
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
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 {
private String[] fonts;
private final JLabel jlab;
private int index = 0;
public TestPane() {
setLayout(new GridBagLayout());
fonts = GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames();
jlab = new JLabel("This is Label");
add(jlab);
Timer timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
updateFont();
index++;
if (index >= fonts.length) {
((Timer)e.getSource()).stop();
}
}
});
timer.setInitialDelay(0);
timer.start();
}
protected void updateFont() {
System.out.println(fonts[index]);
jlab.setText(fonts[index]);
jlab.setFont(new Font(fonts[index], Font.PLAIN, 30));
jlab.setForeground(Color.DARK_GRAY);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}

How to change images in jlable automatically

I am trying to display different images in 3 different jlables. There is a folder with images in them. I have display the images in the jlable and the image has to change after 60 seconds. No matter what I try I cannot do it. Can somebody help me.

The simple answer is, use a Swing Timer, it allows you to schedule a callback in the future, which is delivered within the context of the Event Dispatching Thread, making it safe to update the UI from, for example...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
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 {
private JLabel label;
private File[] images;
private int imageIndex;
public TestPane() {
setLayout(new BorderLayout());
label = new JLabel();
label.setHorizontalAlignment(JLabel.CENTER);
label.setVerticalAlignment(JLabel.CENTER);
add(label);
images = new File("...").listFiles();
imageIndex = -1;
nextImage();
Timer timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
nextImage();
}
});
timer.start();
}
protected void nextImage() {
if (images.length > 0) {
imageIndex++;
if (imageIndex >= images.length) {
imageIndex = 0;
}
try {
BufferedImage image = ImageIO.read(images[imageIndex]);
label.setIcon(new ImageIcon(image));
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
}
}
Have a look at How to use Swing Timers for more details.
If your images are large or are coming from a slow service (like over the internet), you might consider using a SwingWorker instead, this allows you to perform long running or blocking operations in the background (off the EDT), but which are easier to synchronise updates back to the EDT with. Have a look at Refresh Image in JLabel with Timer for more details

Making a slideshow program

I am trying to make a slideshow program. I want the next slide to appear when I click (There are only two slides not, but I will add more once the errors r sorted out).
The code compiles fine. But when i click, nothing happens.
What could possibly go wrong?
package project;
import java.awt.BorderLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Frame extends JFrame{
Frame() {
setLayout(new BorderLayout());
ImageIcon slide = new ImageIcon("E:\\Books\\Computer\\Java\\Introduction to Java Programming\\exercise9e\\image\\slide0.jpg");
JLabel slidesLabel = new JLabel(slide);
add(slidesLabel,BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
}
public void nextSlide() {
ImageIcon slide = new ImageIcon("E:\\Books\\Computer\\Java\\Introduction to Java Programming\\exercise9e\\image\\slide1.jpg");
JLabel slidesLabel = new JLabel(slide);
add(slidesLabel,BorderLayout.CENTER);
System.out.println("x");
}
public static void main(String args[]) {
Frame frame = new Frame();
frame.setSize(800,600);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setVisible(true);
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}

So, the "main" problem is BorderLayout will only manage a single component within any of the five available locations it manages.
Adding another component into the position tends to cause issues, where the component that was first added won't be displayed, or in your case, will remain and could interfere with the new component
"A" solution would be to re-use the same JLabel for each slide, simply supply a new value for the icon property (or in this example, the text property)
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Frame extends JFrame {
private JLabel slidesLabel = new JLabel("Apple");
public Frame() {
setLayout(new BorderLayout());
add(slidesLabel, BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
}
public void nextSlide() {
slidesLabel.setText("Banana");
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Frame frame = new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}
This approach would allow you to place each icon into an array and simply have a counter which determines which slide is current, so when you click for the next slide, you simply increment the counter, get the next value from the array and apply it to the label
A better (and more appropriate) solution would be to actually use a CardLayout, see How to Use CardLayout for more details
With icons...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Frame extends JFrame {
private JLabel slidesLabel = new JLabel();
private Icon[] icons;
private int currentSlide = -1;
public Frame() {
try {
// Personally, I'd use File#listFiles to list all the
// images in a directory, but that might be consider
// using our initiative...
icons = new Icon[]{
new ImageIcon(ImageIO.read(new File("..."))),
new ImageIcon(ImageIO.read(new File("..."))),
new ImageIcon(ImageIO.read(new File("...")))
};
slidesLabel.setVerticalAlignment(JLabel.CENTER);
slidesLabel.setHorizontalAlignment(JLabel.CENTER);
setLayout(new BorderLayout());
add(slidesLabel, BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
nextSlide();
} catch (IOException exp) {
exp.printStackTrace();
}
}
public void nextSlide() {
if (currentSlide < icons.length - 1) {
currentSlide++;
slidesLabel.setIcon(icons[currentSlide]);
}
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Frame frame = new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}
Why simply adding components to a BorderLayout is bad...
All I did was when nextSlide was called, create a new JLabel assign it the next icon and add it to the Frame (which is using a BorderLayout) and then re-sized the frame. Because the labels are transparent, they remain visible...
This is why you shouldn't simply add new components to a BorderLayout, but, in your case, simply update the properties of the existing JLabel to meet the changing needs.

How I can define a JRadioButton with large size?

I'm learning java. for my GUI program need to large radio buttons (larger than the standard). What can I do?
I use Java Netbeans IDE - the latest version.

You can supply you're own images for radio button, see JRadioButton#setIcon, JRadioButton#setSelectedIcon and How to Use Buttons, Check Boxes, and Radio Buttons for more details...
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class RadioButtonTest {
public static void main(String[] args) {
new RadioButtonTest();
}
public RadioButtonTest() {
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() {
try {
BufferedImage checked = ImageIO.read(getClass().getResource("/Checked.png"));
Image unchecked = ImageIO.read(getClass().getResource("/Unchecked.png")).getScaledInstance(300, 300, Image.SCALE_SMOOTH);
JRadioButton btn = new JRadioButton("I'm not fat, I'm just big boned");
btn.setSelectedIcon(new ImageIcon(checked));
btn.setIcon(new ImageIcon(unchecked));
btn.setHorizontalTextPosition(JRadioButton.CENTER);
btn.setVerticalTextPosition(JRadioButton.BOTTOM);
setLayout(new GridBagLayout());
add(btn);
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
}

KeyListener not working

public class KL implements KeyListener {
public static void main(String[] args) {
final JPopupMenu popup = new JPopupMenu();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 200);
frame.setVisible(true);
}
#Override
public void keyPressed(KeyEvent arg0) {
System.out.println(arg0.getKeyChar());
}
#Override
public void keyReleased(KeyEvent e) {
System.out.println(e.getKeyChar());
}
#Override
public void keyTyped(KeyEvent e) {
System.out.println(e.getKeyChar());
}
}
That's my class, it's probably something really stupid on my part, but my KeyListener here is not working. Nothing comes up on the console.

Let's start with the fact that you're not attached the listener to anything, then move on to the fact that you really should be using Key Bindings
And with example
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestTableEditing {
public static void main(String[] args) {
new TestTableEditing();
}
public TestTableEditing() {
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 TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JLabel key;
private int counter = 0;
public TestPane() {
key = new JLabel("...");
add(key);
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0), "A.pressed");
am.put("A.pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("A was pressed");
key.setText("A was pressed " + (++counter));
}
});
}
}
}

I know this is an old post but I wanted to put this online so someone like myself can find it....
I worked on this problem for hours before figuring it out. Make sure that your Component has focus. For example I have all of my activity going on in a custom JPanel named SpaceShipPanel:
class SpaceShipPanel
{
//instance variables
//Now my constructor
SpaceShipPanel(){
//bla bla blah
setFocusable(true);//THIS LINE IS WHAT SAVED ME!!
}
}
From what I hear, keyBindings are the best route but the class I'm taking didn't cover this topic. Hopefully this will save someone hours of beating their heads against the wall.