How to catch a java unchecked/runtime exception (specifically SecurityException)

Question

Hi all,

I have java class with a method which gets an image from a website:

private Image image;
private int height;
private int width;
private String imageUri;

public Image getImage() {
 if (image == null) {
  log.info("Fetching image: " + imageUri);
  try {
   URL iURL = new URL(imageUri);
   ImageIcon ii = new ImageIcon(iURL);
   image = ii.getImage();
   height = image.getHeight(null);
   width = image.getWidth(null);
  } catch (SecurityException e) {
   log.error("Unable to fetch image: " + imageUri,e);
  } catch (MalformedURLException e) {
   log.error("Unable to fetch image: " + imageUri,e);
  }
 }
 return image;
}

The problem is that sometimes the imageUri I try to fetch gets redirected, causing the ImageIcon constructor to throw a java.lang.SecurityException - which is not caught by the catch clause, causing my program to terminate.

Can anyone suggest how I might catch this exception?

Thanks

Answer 1

If the exception indeed thrown from getImage(), your code should catch it. SecurityException is Exception. You've got it wrong somewhere. For instance, place ImageIcon constructor under try. If it doesn't help, try

catch( Throwable th )

It's a bad habit though. Try at least to re-throw it (or a wrapper exception) after logging it.

Answer 2

The exception is being thrown by the constructor, which is not wrapped in the try block.

new ImageIcon(new URL(imageUri))

Answer 3

I have discovered the issue: the ImageIcon constructor spawns a separate thread, and the exception is being thrown from there, hence I cannot catch it.

Answer 4

Using ImageIcon to load an image is sooooo 1998. You want ImageIO.read().

Answer 5

Due to ImageIcon being extremely old school, and spawning a new thread (which i do not want) , my solution is as follows:

public Image getImage() {
 if (image == null) {
  log.info("Fetching image: " + imageUri);
  try { 
   URL iURL = new URL(imageUri);
   InputStream is = new BufferedInputStream(iURL.openStream());
   image = ImageIO.read(is);
   height = image.getHeight();
   width = image.getWidth();
  } catch (MalformedURLException e) {
   log.error("Unable to fetch image: " + imageUri, e);
  } catch (IOException e) {
   log.error("Unable to fetch image: " + imageUri, e);
  }
 }
 return image;
}

Any issues with redirects, dead links etc are now handled gracefully.