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I am attempting to dynamically add an image to my JLabel then add the JLabel to my panel. My code is throwing no errors, but the image is never shown.
public JFrameGamePlay(String playername, String playerselected) {
initComponents();
playerimage = "/Users/owner/Downloads/__Pikachu.png";
ImageIcon pimage = new ImageIcon(playerimage);
JLabel lblPlayer = new JLabel(pimage);
pnlPlayer.add(lblPlayer);
pnlPlayer.validate();
pnlPlayer.repaint();
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new JFrameGamePlay().setVisible(true);
}
});
}
EDIT
So from further googling I came up with this syntax
JLabel lblPlayer;
lblPlayer = new JLabel(new ImageIcon(getClass().getClassLoader().getResource("__Image1.png")));
pnlPlayer.add(lblPlayer);
pnlPlayer.validate();
pnlPlayer.repaint();
but when I run the code I get this debug error:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:217)
This is the GUI layout of how I want my data to appear - it is 1 panel on the left and 1 panel on the right - each with a label dynamically created and populated with an image. But no image is being populated.
EDIT 2
I added a black border around my 2 Panels, and when the JForm is loaded neither panel is being displayed. So it seems that what everyone is telling me that GUI designing in NetBeans is pretty buggy. How can I dynamically in my code behind add the two panels one left and one right with a size of 143, 246?
EDIT 3
Still no mustard and I'm using this syntax:
public JFrameGamePlay() {
initComponents();
JPanel leftpanel = new JPanel();
JPanel rightpanel = new JPanel();
JSplitPane pane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftpanel, rightpanel);
JLabel lblPlayer = new JLabel(new ImageIcon("/resources/__Image1.png"));
leftpanel.add(lblPlayer);
leftpanel.validate();
leftpanel.repaint();
}
Use ImageIO.read(File) to read the Image. Like,
File playerimage = new File("/Users/owner/Downloads/__Pikachu.png");
ImageIcon pimage = new ImageIcon(ImageIO.read(playerimage));
JLabel lblPlayer = new JLabel(pimage);
pnlPlayer.add(lblPlayer);
The NullPointerException comes from the getResource("__Image1.png") returning null because it didn't find the file. You should prefix it with the location from the classpath (after all, the ClassLoader loads the file). E.g. if the image is in a res directory in your jar (or in your classpath):
JFrameGamePlay.class.getClassLoader().getResource("/res/__Image1.png")));
Or you can directly give a complete path:
new JLabel(new ImageIcon("/images/thewall.png"));
Example:
public class JFrameGamePlay extends JFrame {
private static final long serialVersionUID = 1L;
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(100, 100, 450, 300);
JPanel contentPane = new JPanel(new BorderLayout());
frame.setContentPane(contentPane);
JLabel label = new JLabel(new ImageIcon("/images/thewall.png"));
contentPane.add(label, BorderLayout.CENTER);
JLabel label1 = new JLabel(new ImageIcon(JFrameGamePlay.class.getResource("/javax/swing/plaf/basic/icons/JavaCup16.png")));
contentPane.add(label1, BorderLayout.NORTH);
frame.setVisible(true);
}
}
My code is throwing no errors, but the image is never added.
Yes, this is unfortunately how ImageIcon works. It doesn't throw exceptions or anything if it's unable to read from the filename or URL you pass to it. The code runs without error but simply shows nothing.
playerimage = "/Users/owner/Downloads/__Pikachu.png";
If you want to read from a file at a fixed location like this, then it won't be helpful to mess with getClassLoader().getResource(). That could be helpful to read an image file that you package with your application, but not to read an image in the user's home directory. Your original new ImageIcon(imageLocation) approach is appropriate for that.
[note: I think it's a good idea to send the filename (or URL) directly to the ImageIcon, as your original code does. Other answers suggest ImageIO.read(), which can be helpful to see where it's going wrong, but you could change it back to ImageIcon(filenameOrUrl) once you get it working. But it's not a big deal.]
I am attempting to dynamically add an image to my JLabel then add the JLabel to my panel.
If by "dynamically" you mean to do this when some event occurs, after the panel is already visible on the screen, then I suggest not doing that.
That is, instead of doing this...
JLabel lblPlayer = new JLabel(pimage);
pnlPlayer.add(lblPlayer);
pnlPlayer.validate();
pnlPlayer.repaint();
...you could add the JLabel to your panel (invisible because no text or image) at the very start, before your panel is shown on screen. Then dynamically add the ImageIcon to the already-extant JLabel. All you need to call is existingLabel.setIcon(...). There would be no need to call validate() or repaint().
Related
I hope everyone is doing alright this fine day.
I'm learning swing and I was confused by how to reference an image. I understand that I should use a JLabel and then add that JLabel to the Frame using this.add();, but even looking at the oracle documentation here:
https://docs.oracle.com/javase/6/docs/api/javax/swing/ImageIcon.html
It is still unclear how to reference a file without giving the entire path like
C:\Users\someUser\eclipse-workspace\andSoOn.png
And I can't do that. I have to send my work to my teacher once I'm done, and the code won't reference the file like it does on my system. I tried several things, and I ended up making a new folder in the src in eclipse called ImageAssets and moving the files there, but nothing seems to work. Here is what it looks like
Here is an example of my attempt to display an image from within the package.
import java.awt.*;
import javax.swing.*;
public class Hangman extends JFrame
{
JButton playGameButton,
OptionsButton;
private ImageIcon hangman7;
private JLabel mainLabel;
public static void main(String[] args)
{
new Hangman();
}
public Hangman()
{
this.setSize(1000,800);
this.setLocationRelativeTo(null);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Hangman");
this.setResizable(false);
playGameButton = new JButton("Start Game");
OptionsButton = new JButton("Options");
//hangman7 = new ImageIcon(getClass().getResource("Images\\ hangman7.png"));//just an attempt at something
mainLabel = new JLabel();
mainLabel.setIcon(new ImageIcon("hangman7.png"));
JPanel somePanel = new JPanel();
somePanel.setLayout(new BorderLayout());
somePanel.add(playGameButton, BorderLayout.WEST);
somePanel.add(OptionsButton, BorderLayout.EAST);
somePanel.add(mainLabel, BorderLayout.CENTER);
this.add(somePanel);
this.validate();
}
Thank you so much for taking the time to help me. I tried to be very detailed; if anything is unclear please ask.
In your case, you want let the class loader find the resource, like this:
mainLabel.setIcon(
new ImageIcon(getClass().getResource("/ImageAssets/hangman7.png")));
I'm having a problem that seems a little bit strange. When I'm adding a new ImageIcon and try to run the program it just gives me a gray screen and no objects are added.
public class Ctester {
public Ctester(){
Frame();
}
public void Frame(){
JFrame fr = new JFrame();
fr.setVisible(true);
fr.setSize(500, 500);
fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fr.setResizable(false);
JPanel p = new JPanel(new GridBagLayout());
ImageIcon icon = new ImageIcon(getClass().getResource("zippo.jpg"));
JLabel l = new JLabel(icon)
JButton bm1 = new JButton("hellu");
p.add(l);
p.add(bm1);
fr.add(p);
}
public static void main(String[]args){
new Ctester();
}
}
But if I remove the line:
ImageIcon icon = new ImageIcon(getClass.getResource("zippo.jpg"));
then it works perfect.
I'm not getting any error messages and i been looking for a while but I could only find that the problem might be something with the gridbaglayout.
How can i solve it or do I have to change layout?
(this is just a simple code based of the original as an example so any solutions that not include having to change layout is highly appreciated)
Most of the code is wrong:
Swing components should be create on the Event Dispatch Thread (EDT).
The frame should be made visible AFTER all the components have been added to the frame.
You are attempting to use a GridBagLayout, but you aren't using any GridBagConstraints when you add the components.
Method names (Frame) should NOT start with an upper case character.
Read the Swing Tutorial for Swing basics.
You can find working examples in:
How to Use GridBagLayout
How to Use Icons
so any solutions that not include having to change layout is highly appreciated
Start with the working examples and make changes for your requirements. If you start with better structured code you will have less problems.
If something draws correctly after a window resize or minimize/maximize that is a sure sign of a race condition because you are not starting your GUI on the event dispatcher thread. Your main problem is you are calling setVisible() way to early, don't call setVisible() until after you have added all components to your top-level container. The other problem is you are not starting your GUI on the event dispatcher thread. Please see the main method below in the fixed code:
public class Ctester {
public Ctester() {
Frame();
}
public void Frame() {
JFrame fr = new JFrame();
fr.setSize(500, 500);
fr.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fr.setResizable(false);
JPanel p = new JPanel(new GridBagLayout());
JLabel l = new JLabel("label");
JButton bm1 = new JButton("hellu");
p.add(l);
p.add(bm1);
fr.add(p);
fr.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Ctester();
}
});
}
}
Try this code you might want to put that first line of code in a try catch just in case that it doesn't find the image.
URL iconURL = getClass().getResource("/some/package/favicon.png");
// iconURL is null when not found
ImageIcon icon = new ImageIcon(iconURL);
fr.setIconImage(icon.getImage());
Also use a .ico file if you are only using this program on Windows but use a .png if it is going to be multi-platform
i recently code a system homepage that include the background image. After i set the background, the button that i created cannot show properly. It just appear after i use the mouse and point to the buttons' location. Can someone teach me how to fix this problem? Your help are appreciated. The codes are as below:
public class HomePage extends JFrame{
private JPanel button = new JPanel();
private JButton time = new JButton("Bus Schedule");
private JButton reserve = new JButton("Booking");
private JButton info = new JButton("About Us");
Container con = getContentPane();
public HomePage(){
setTitle("Bus Reservation System");
setSize(650,500);
setLocation(360,100);
setVisible(true);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setBackground();
setButton();
}
public void setBackground(){
JLabel background = new JLabel(new ImageIcon("C:/User/Desktop/Assignment/bg.jpg"));
con.add(background);
background.setLayout(new FlowLayout());
con.add(button);
}
public void setButton(){
Font but = new Font("Serif" , Font.ITALIC , 20);
info.setFont(but);
time.setFont(but);
reserve.setFont(but);
button.add(info);
button.add(time);
button.add(reserve);
con.add(button);
}
After you call setVisible(true), if you perform certain actions, you must manually validate() or revalidate() your window.
It is simpler to just call setVisible() after you have initialized all of the desired settings and membership of the window.
/* setVisible(true); -- wrong place */
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setBackground();
setButton();
setVisible(true); // proper place
Simple mistake (probably a typo?), you are setting the layout of the JLabel, you intended to set the layout of the Container. Do con.setLayout(new FlowLayout()); instead of background.setLayout(...)
Also, I believe your path to the file is incorrect. For testing, just put the file in the project and do a path like "bg.jpg", if that works, we can verify this. For me that works. The reason I believe this is the issue is because you specify C:/Users, but then never give the folder for the specific User. A correct path would be C:/Users/Your_name/Desktop/Assignment/bg.jpg
I don't know for sure on that path part, since I'm not on your system. However, for me, if I run your code in my eclipse, this fixes it.
edit:
One last thing, the image isn't really going to be a "background" image with the current code because it will move the buttons underneath it instead of on top of it with the FlowLayout. You may want to use a different Layout.
First of all as already noted, all components should be added to the frame BEFORE invoking setVisible(true) on the JFrame.
JLabel background = new JLabel(new ImageIcon("C:/User/Desktop/Assignment/bg.jpg"));
con.add(background);
background.setLayout(new FlowLayout());
con.add(button);
Based on the above code you are adding two components to the content pane so the hierarchy of your GUI looks like this:
- frame
- content pane
- background
- button
It seems to me you want your GUI to look like this:
- frame
- content pane
- background
- button
So your code should be:
JLabel background = new JLabel(new ImageIcon("C:/User/Desktop/Assignment/bg.jpg"));
con.add(background);
background.setLayout(new FlowLayout());
//con.add(button);
background.add( button );
I am very confused. Why would this method not work for displaying an image:
private void showImage(final BufferedImage image){
SwingUtilities.invokeLater(
new Runnable(){
#Override
public void run(){
ImageIcon icon = new ImageIcon(image);
JLabel label = new JLabel();
label.setIcon(icon);
add(label, BorderLayout.CENTER);
}
}
);
}
My class extends JFrame, so that's why I'm not doing something like:
frame.add(label);
I am very confused. I have tried this without the whole SwingUtilities thing and also I have tried label.setVisible(true)
What the heck am I doing wrong here? When I run it I know this method is being called with a completely okay BufferedImage (I had it output something in the method). I expected a JLabel to come up with my image on it, but just the JFrame came up, no image in sight.
add(label, BorderLayout.CENTER);
When you add (or remove) a component from a visible GUI the basic code is:
panel.add(...);
panel.revalidate();
panel.repaint();
In your case you would revidate the frame since you are adding the label to the content pane of the frame.
That is you need to invoke the layout manager, otherwise the component has a size of (0, 0) so there is nothing to paint.
However, a better solution would probably be to add the label to the GUI when you create the frame.
Then to change the icon you just do:
label.setIcon(...);
No need to create a new JLabel every time you want to change the image.
I'm very new to Java and I'm trying to create a small program that reverses text (That part I've figured out).
Where I'm getting stuck on is my GUI, my envisioned plan for the gui is a window with a centered text field for user input then under it in the directly middle of the window a button that reverses the text from the above text box and outputs it in a text box below the button.
Right now I'm using JTextField boxes and after trying to make them look the way I want I'm getting the feeling that there's an easier way to do it, but I don't know it.
Here's my GUI class:
public class ReverseTextGUI extends ReverseRun implements ActionListener {
public static JFrame frame;
private JPanel northFlowLayoutPanel;
private JPanel centerFlowLayoutPanel;
private JPanel southFlowLayoutPanel;
private final JButton reverse = new JButton("Reverse");
private final JTextField userInput = new JTextField(50);
private final JTextField reverseOutput = new JTextField(50);
public void actionPerformed(ActionEvent e) {
reverse.addActionListener((ActionListener) reverse);
reverse.setActionCommand("Reverse");
if ("algorithm".equals(e.getActionCommand())) {
System.out.println("test");
}
}
public void initUI() {
northFlowLayoutPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
northFlowLayoutPanel.add(userInput);
userInput.setPreferredSize(new Dimension(150,100));
centerFlowLayoutPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
centerFlowLayoutPanel.add(reverse);
southFlowLayoutPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
southFlowLayoutPanel.setBorder(BorderFactory.createTitledBorder("Output text"));
southFlowLayoutPanel.add(reverseOutput);
reverseOutput.setPreferredSize(new Dimension(150,100));
JFrame frame = new JFrame("Backwardizer");
frame.setLayout(new BorderLayout()); // This is the default layout
frame.add(northFlowLayoutPanel, BorderLayout.PAGE_START);
frame.add(centerFlowLayoutPanel, BorderLayout.CENTER);
frame.add(southFlowLayoutPanel, BorderLayout.PAGE_END);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setSize(750, 500);
}
Any ideas how to either move the cursor to the start of the box (it shows up in the middle as of now) or a better way to accomplish what I'm trying to do?
For the reversing aspect, you can add the text from the first box to a string builder
StringBuilder rev = new StringBuilder(firstBox.getText());
String reversedText = rev.reverse().toString();
secondBox.setText(reversedText);
Something along those line should get the desired result if you nest it in the button action.
Any ideas how to either move the cursor to the start of the box (it shows up in the middle as of now) or a better way to accomplish what I'm trying to do?
JTextField#setCaretPosition, call this AFTER you've updated the text of the field
Make the field readonly, JTextField#setEditable and pass it false
Additionally, you could use a JList or JTextArea if you want to store multiple rows/lines of text
You should also avoid using setPreferredSize, see Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing? for more details