I've gone through every post I could find on this site and the Java tutorials and I still can't figure out why my code isn't working. Even when I copy/paste other peoples' code, it still doesn't work.
I've made a dummy program just to test this out and the code looks like so:
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
public class gui extends JFrame {
private JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
gui frame = new gui();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public gui() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 900, 700);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lblNewLabel = new JLabel(new ImageIcon("bg.png"));
contentPane.add(lblNewLabel);
}
}
The background image I'm trying to display, bg.png, is located in the project's root folder. I tried multiple formats for the path string with no success. What am I doing wrong?
What you're doing wrong is that when you call new ImageIcon("bg.png"), you try loading the bg.png file from the current directory. The current directory is the directory from which java is executed. And the current directory is probably not the directory you believe when you execute java from your IDE.
Use the following code to display the current directory:
File dir1 = new File (".");
System.out.println("current directory: " + dir1.getAbsolutePath());
You should probably load the png file from the classpath, using Class.getResource("/images/bg.png"). Create an images folder in your source directory, and put the file in this directory. Your IDE will copy it to the target folder, along with the .class files. If you're not using an IDE, then you'll have to copy it yourself.
EDIT:
After more investigations, it appeared that the root cause of the problem was the use of the null layout. The above still stands, though, because loading a file from the current directory is not a good idea.
You're looking for the image as a file. When you do that the searches are all done in a path relative to the user directory which you can get via
// code not tested
System.out.println(System.getProperty("user.dir"));
So you will likely have to adjust your image's path to get it as a file. The other option is to get it as a resource as noted by Siva Charan in which case the path is relative to the location of your class files.
Oh and once you study and use the layout managers, they become intuitive, and creating and especially maintaing your GUI's become much easier.
Try this way:-
ImageIcon icon = createImageIcon("bg.png", "image description");
protected ImageIcon createImageIcon(String path, String description) {
java.net.URL imgURL = getClass().getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL, description);
} else {
System.err.println("Couldn't find file:" +path);
return null;
}
}
Just simply put your bg.png, alongside your gui.class file. That will do, if you write this code
private ImageIcon getImage(String path)
{
URL url = getClass().getResource(path);
System.out.println(url);
if (url != null)
return (new ImageIcon(url));
return null;
}
More information can be found on Access to Resources
Here path = "bg.png"; or if it's inside some folder than path = "someFolder/bg.png";
So you be writing something like this :
JLabel lblNewLabel = new JLabel(getImage("bg.png"));
lblNewLabel.setBounds(30, 30, 100, 100);
Hope that might help.
Regards
You might need to debug it and check if the image file is loaded correctly. And then you need to check if the JLabel Component gets its size because adding the image to the JLabel wouldn't expand the JLabel.
First you should try to see the image handler has its width and height.
Related
I am having a error for my GUI. Trying to set title bar icon then be included in a Runnable JAR.
BufferedImage image = null;
try {
image = ImageIO.read(getClass().getClassLoader().getResource("resources/icon.gif"));
}
catch (IOException e) {
e.printStackTrace();
}
frame.setIconImage(image);
Here is the error I am getting:
Exception in thread "main" java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(Unknown Source)
at GUI.<init>(GUI.java:39)
at GUI.main(GUI.java:351)
The image is in the correct directory which "resources" folder is the root of the
project file
First of all, change this line :
image = ImageIO.read(getClass().getClassLoader().getResource("resources/icon.gif"));
to this :
image = ImageIO.read(getClass().getResource("/resources/icon.gif"));
More info, on as to where lies the difference between the two approaches, can be found on this thread - Different ways of loading a Resource
For Eclipse:
How to add Images to your Resource Folder in the Project
For NetBeans:
Handling Images in a Java GUI Application
How to add Images to the Project
For IntelliJ IDEA:
Right-Click the src Folder of the Project. Select New -> Package
Under New Package Dialog, type name of the package, say resources. Click OK
Right Click resources package. Select New -> Package
Under New Package Dialog, type name of the package, say images. Click OK
Now select the image that you want to add to the project, copy it. Right click resources.images package, inside the IDE, and select Paste
Use the last link to check how to access this file now in Java code. Though for this example, one would be using
getClass().getResource("/resources/images/myImage.imageExtension");
Press Shift + F10, to make and run the project. The resources and images folders, will be created automatically inside the out folder.
If you are doing it manually :
How to add Images to your Project
How to Use Icons
A Little extra clarification, as given in this answer's first
code example.
QUICK REFERENCE CODE EXAMPLE(though for more detail consider, A little extra clarification link):
package swingtest;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
/**
* Created with IntelliJ IDEA.
* User: Gagandeep Bali
* Date: 7/1/14
* Time: 9:44 AM
* To change this template use File | Settings | File Templates.
*/
public class ImageExample {
private MyPanel contentPane;
private void displayGUI() {
JFrame frame = new JFrame("Image Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
contentPane = new MyPanel();
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private class MyPanel extends JPanel {
private BufferedImage image;
public MyPanel() {
try {
image = ImageIO.read(MyPanel.class.getResource("/resources/images/planetbackground.jpg"));
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return image == null ? new Dimension(400, 300): new Dimension(image.getWidth(), image.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this);
}
}
public static void main(String[] args) {
Runnable runnable = new Runnable() {
#Override
public void run() {
new ImageExample().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
There's a much easier way to load and set an image as a frame icon:
frame.setIconImage(
new ImageIcon(getClass().getResource("/resources/icon.gif")).getImage());
And thats all :)! You don't even have to use a try-catch block because ImageIcon does not throw any declared exceptions. And due to getClass().getResource(), it works both from file system and from a jar depending how you run your application.
If you need to check whether the image is available, you can check if the URL returned by getResource() is null:
URL url = getClass().getResource("/resources/icon.gif");
if (url == null)
System.out.println( "Could not find image!" );
else
frame.setIconImage(new ImageIcon(url).getImage());
The image files must be in the directory resources/ in your JAR, as shown in How to Use Icons and this example for the directory named images/.
Well basically I tried to display a .gif using a url but it's given me a null pointer exception and I'm not really sure why since my url is correct and there's no other problems with my code(At least none that I can see).
import javax.swing.*;
import java.net.*;
public class image {
public image() {
}
public static void main(String[] args) {
URL url = image.class.getResource("<http://cdn.osxdaily.com/wp-content/uploads/2013/07/dancing-banana.gif>");
ImageIcon imageIcon = new ImageIcon(url);
JLabel label = new JLabel(imageIcon);
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.add(label);
frame.add(panel);
frame.setTitle("Title");
frame.setSize(700,500);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
URL url = image.class.getResource("<http://cdn.osxdaily.com/wp-content/uploads/2013/07/dancing-banana.gif>");
is not how you reference an image from a web resources. You would use this method to load resources that are embedded within your application (within the context of the applications classpath)
URL url = new URL("http://cdn.osxdaily.com/wp-content/uploads/2013/07/dancing-banana.gif");
would probably work better...
Remember, that downloading and loading the image may take some time, you may want to use a MediaTracker to track the progress, this would allow you to provide feedback to the user and know when to update the screen with the image once it's available, for example.
Before anyone asks, I choose not to use ImageIO to load an animated gif, because that is just a lot more work (as demonstrated here - not for the faint hearted). In this case, the MediaTracker could be used to check for errors
I am having trouble with this simple example code from the book. It is supposed to represent the same image 2 times in one window (north and south labels), one above the other. When I run it, it displays this instead of this (I am sorry for not cutting the images or resizing them) Below is my code. I am running Eclipse Juno on Ubuntu 13.04.
package gui;
import java.awt.BorderLayout;
import javax.swing.*;
public class Gui {
public static void main(String[] args) {
JLabel northLabel = new JLabel ( "North" );
ImageIcon labelIcon = new ImageIcon ("GUItip.gif");
JLabel centerLabel = new JLabel (labelIcon);
JLabel southLabel = new JLabel (labelIcon);
southLabel.setText("South");
JFrame application = new JFrame();
application.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
application.add(northLabel, BorderLayout.NORTH);
application.add(centerLabel, BorderLayout.CENTER);
application.add(southLabel, BorderLayout.SOUTH);
application.setSize(300, 300);
application.setVisible(true);
}
}
You need to concentrate on the following statement:
ImageIcon labelIcon = new ImageIcon ("GUItip.gif");
When initiating new ImageIcon.. it searches the provided address in execution folder by default i.e. in this case "GUItip.gif" shall be searched within workspace/user directory.
One solution is to make available GUItip.gif image in you workspace (program execution) folder.
Another solution would be to provide absolute path.. eg.
C:\USER\Workspace\project_name\GUItip.gif
Though a better approach would be to create a specific folder where you save all images used in your project. Create a final static String variable with absolute path to your folder. Now it would be easy for any programmer in that project to know where to look for images.
There are good approaches to use this mapping.. through XML to be loaded in the beginning.. through resourcebundle etc but that is a different topic altogether.
The image probably isn't loading properly. Try using a try/catch block to see if that's the case.
Ex:
Image img;
File f = new File(//image url);
try {
img = ImageIO.read(f);
} catch (IOException e) {
String curr_dir = System.getProperty("user.dir");
throw new IllegalArgumentException("Image could not be found from " + curr_dir);
}
ImageIcon labelIcon = new ImageIcon(img);
I am having a error for my GUI. Trying to set title bar icon then be included in a Runnable JAR.
BufferedImage image = null;
try {
image = ImageIO.read(getClass().getClassLoader().getResource("resources/icon.gif"));
}
catch (IOException e) {
e.printStackTrace();
}
frame.setIconImage(image);
Here is the error I am getting:
Exception in thread "main" java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(Unknown Source)
at GUI.<init>(GUI.java:39)
at GUI.main(GUI.java:351)
The image is in the correct directory which "resources" folder is the root of the
project file
First of all, change this line :
image = ImageIO.read(getClass().getClassLoader().getResource("resources/icon.gif"));
to this :
image = ImageIO.read(getClass().getResource("/resources/icon.gif"));
More info, on as to where lies the difference between the two approaches, can be found on this thread - Different ways of loading a Resource
For Eclipse:
How to add Images to your Resource Folder in the Project
For NetBeans:
Handling Images in a Java GUI Application
How to add Images to the Project
For IntelliJ IDEA:
Right-Click the src Folder of the Project. Select New -> Package
Under New Package Dialog, type name of the package, say resources. Click OK
Right Click resources package. Select New -> Package
Under New Package Dialog, type name of the package, say images. Click OK
Now select the image that you want to add to the project, copy it. Right click resources.images package, inside the IDE, and select Paste
Use the last link to check how to access this file now in Java code. Though for this example, one would be using
getClass().getResource("/resources/images/myImage.imageExtension");
Press Shift + F10, to make and run the project. The resources and images folders, will be created automatically inside the out folder.
If you are doing it manually :
How to add Images to your Project
How to Use Icons
A Little extra clarification, as given in this answer's first
code example.
QUICK REFERENCE CODE EXAMPLE(though for more detail consider, A little extra clarification link):
package swingtest;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
/**
* Created with IntelliJ IDEA.
* User: Gagandeep Bali
* Date: 7/1/14
* Time: 9:44 AM
* To change this template use File | Settings | File Templates.
*/
public class ImageExample {
private MyPanel contentPane;
private void displayGUI() {
JFrame frame = new JFrame("Image Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
contentPane = new MyPanel();
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private class MyPanel extends JPanel {
private BufferedImage image;
public MyPanel() {
try {
image = ImageIO.read(MyPanel.class.getResource("/resources/images/planetbackground.jpg"));
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return image == null ? new Dimension(400, 300): new Dimension(image.getWidth(), image.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this);
}
}
public static void main(String[] args) {
Runnable runnable = new Runnable() {
#Override
public void run() {
new ImageExample().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
There's a much easier way to load and set an image as a frame icon:
frame.setIconImage(
new ImageIcon(getClass().getResource("/resources/icon.gif")).getImage());
And thats all :)! You don't even have to use a try-catch block because ImageIcon does not throw any declared exceptions. And due to getClass().getResource(), it works both from file system and from a jar depending how you run your application.
If you need to check whether the image is available, you can check if the URL returned by getResource() is null:
URL url = getClass().getResource("/resources/icon.gif");
if (url == null)
System.out.println( "Could not find image!" );
else
frame.setIconImage(new ImageIcon(url).getImage());
The image files must be in the directory resources/ in your JAR, as shown in How to Use Icons and this example for the directory named images/.
My goal is to have an imageIcon and add it so a JLabel so it will appear on my GUI. So far my code is:
package classes;
import javax.swing.*;
public class Picture extends JFrame {
private ImageIcon _image1;
private JLabel _mainLabel;
public Picture(){
_image1 = new ImageIcon("picture1.jpg");
_mainLabel = new JLabel(_image1);
add(_mainLabel);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
package classes;
public class Driver {
public static void main(String[] args) {
Picture p = new Picture();
}
}
The problem is the picture does not appear on my GUI. If anyone has any suggestions please let me know thanks!
Are you sure that Java is looking in the right location for your picture1.jpg file? Is this file located in the current working directory?
Put this code somewhere in your program so that it gets called when the program is run:
// show the current working directory
System.out.println("current working directory is: " + System.getProperty("user.dir"));
The String returned will tell you where Java is looking, where your current working directory is located. You can then use that information to adjust your path or you could always just use the full path to the image file.
Edit:
Also, don't forget to pack your JFrame so that it will layout the components and size itself accordingly:
public Picture() {
_image1 = new ImageIcon(IMAGE);
_mainLabel = new JLabel(_image1);
add(_mainLabel);
pack(); // to tell the layout managers to set up the GUI
setLocationRelativeTo(null); // center things
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
For setting image to jlabel simple put one line code in your program :
yourlabel.setIcon(new javax.swing.ImageIcon(getClass().getResource("your image location here")));
we can set Jlabel with image and text also.