Loading resources like images while running project distributed as JAR archive

Question

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

Answer 1

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()); 

Answer 2

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);     } }