NullPointerException JApplet with getClass().getResource

Question

I want to add an image to JPanel in JApplet (so that I could create the jar file), so I used :

Image x = Toolkit.getDefaultToolkit().getImage(
  getClass().getResource("D:/THANH_TAI LIEU/niet/hinhtu.jpg"));

but the java.lang.NullPointerException occured. I'm sure the image path is correct, because the applet run fine when I used :

Image image = ImageIO.read(new File("D:/THANH_TAI LIEU/niet/hinhtu.jpg"));

The exceptions :

    Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at sun.awt.SunToolkit.getImageFromHash(SunToolkit.java:830)
at sun.awt.SunToolkit.getImage(SunToolkit.java:887)
at applet$CustomPanel.paintComponent(applet.java:65)
at javax.swing.JComponent.paint(JComponent.java:1029)
at javax.swing.JComponent.paintChildren(JComponent.java:862)
at javax.swing.JComponent.paint(JComponent.java:1038)
at javax.swing.JComponent.paintChildren(JComponent.java:862)
at javax.swing.JComponent.paint(JComponent.java:1038)
at javax.swing.JComponent.paintChildren(JComponent.java:862)
at javax.swing.JComponent.paint(JComponent.java:1038)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:567)

The code:

  import java.awt.BorderLayout;
  import java.awt.Color;
  import java.awt.Graphics;
  import java.awt.Image;
  import java.awt.Toolkit;
  import java.io.File;
  import java.io.IOException;

  import javax.imageio.ImageIO;
  import javax.swing.BorderFactory;
  import javax.swing.ImageIcon;
  import javax.swing.JApplet;
  import javax.swing.JButton;
  import javax.swing.JLabel;
  import javax.swing.JPanel;

  public class applet extends JApplet {
  public void init() {
    //Execute a job on the event-dispatching thread:
    //creating this applet's GUI.
    try {
        javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
                createGUI();
            }
        });
    } catch (Exception e) {

        e.printStackTrace();
    }
}

  private void createGUI() {
    JPanel panel = new JPanel(new BorderLayout());
    JButton button = new JButton("CLICK ME");
    panel.add(button, BorderLayout.SOUTH);
    panel.add(new CustomPanel(), BorderLayout.CENTER);

    add(panel);
    }

public class CustomPanel extends JPanel{

    public void paintComponent(Graphics g) {

        Image image = null;
        try {
            image = ImageIO.read(new File("D:/THANH_TAI LIEU/niet/hinhtu.jpg"));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Image x = Toolkit.getDefaultToolkit().getImage(getClass().getResource("D:/THANH_TAI LIEU/niet/hinhtu.jpg"));
        g.drawImage(x, 0, 0, null); 

    }   



}
}

What could be the problem?

I guess `getClass().getResource(...)` demands relative path with respect to your class file. So depending on that you need to specify, where you image is located. How come your `Toolkit` will know where is `Drive D`. Check this link for further help : [How to add images](http://stackoverflow.com/questions/9864267/load-icon-image-exception/9866659#9866659). — nIcE cOw, Apr 12 '12 at 05:25
Yeah, the problem solved. I put the pic into the same path with the class file, and getResource("/hinhtu.jpg")); - it worked!! — TU_HEO DAKAI, Apr 12 '12 at 05:33
That code still has some problems, even if the resource is found. 1) Trying to load 2 images in `paintComponent()` - never load resources in that method. 2) Using `null` as the `ImageObserver` for the drawing, when `this` (the `JPanel`) **is an** `ImageObserver`. -- Is it intended to add any components on top of `CustomPanel`, or to draw anything else to it? If not, just put the image in a label and add it to the CENTER of the parent panel. — Andrew Thompson, Apr 12 '12 at 08:01

score 3 · Accepted Answer · answered Apr 12 '12 at 05:42

3

getClass().getResource()
Works only for the class path of the project.
You need to put the image file on the class path in order to find
Where ImageIO.read() can read whatever is passed in the params as input stream.

answered Apr 12 '12 at 05:42

GingerHead

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NullPointerException JApplet with getClass().getResource

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