Java - ImageIO throws IllegalArgumentException

Question

Hello Java Developers,

So I have recently encountered this problem. Here's and SSCCE:

public class SampleClass extends JPanel{

    private Image img;
    private final String IMG_DIRECTORY = ("/res/BG.png");

    public SampleClass(){

        try{
            img = ImageIO.read(getClass().getResource(IMG_DIRECTORY));
        } catch (IOException ioEx) {
            ioEx.printStackTrace();
        }
    }

    @Override
    public void paintComponent(Graphics g){
        super.paintComponent(g);

        g.drawImage(img, 0, 0, null);
    }

}

This line throws the exception

img = ImageIO.read(getClass().getResource(IMG_DIRECTORY));

Here's the StackTrace:

Exception in thread "main" java.lang.IllegalArgumentException: input == null!
    at javax.imageio.ImageIO.read(Unknown Source)
    at com.forte.project.chatservice.uicomponent.FrameBackground.<init>(FrameBackground.java:27)
    at com.forte.project.chatservice.ui.MainFrame.<init>(MainFrame.java:27)
    at com.forte.project.chatservice.ChatService.main(ChatService.java:18)

I have done the following:
- Google.
- Updated my Java
- .getResourceAsStream(IMG_DIRECTORY);
- this.getClass().getResource(IMG_DIRECTORY));
- MainClass.class.getClass().getResource(IMG_DIRECTORY);

print `getClass().getResource(IMG_DIRECTORY)` what does it produces? — Nikolay Kuznetsov, Jan 27 '13 at 05:46
@sansix Line 27 is: img = ImageIO.read(getClass().getResource(IMG_DIRECTORY)); and 18 @ MainClass is: SampleClass sample= new SampleClass(); — Michael 'Maik' Ardan, Jan 27 '13 at 05:52
Try removing the preceding / from IMG_DIRECTORY ie IMG_DIRECTORY = "res/BG.png";. Based on its current value, it may be trying to access a resource in the base directory. — Sinkingpoint, Jan 27 '13 at 06:24
1) Edit the output from `jar -tvf the.jar` into the question. 2) An [SSCCE](http://sscce.org/) requires a `main(String[])` to be an SSCCE (unless it is an applet, servlet etc.). 3) `g.drawImage(img, 0, 0, null);` should be `g.drawImage(img, 0, 0, this);` 4) But see [`ImageViewer`](http://stackoverflow.com/a/13512826/418556). Image(s) centered in a scroll pane. — Andrew Thompson, Jan 27 '13 at 06:32
Try copy pasting your `BG.png` in your package directly,and then use `IMG_DIRECTORY = ("BG.png")` does it still gives you an NP Exception? — joey rohan, Jan 27 '13 at 08:01

score 0 · Accepted Answer · answered Jan 27 '13 at 08:49

0

Placing res folder to src folder fixed the problem.

answered Jan 27 '13 at 08:49

Michael 'Maik' Ardan

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Java - ImageIO throws IllegalArgumentException

1 Answers1