Question

Say I have the following line in a method:

 String encodedString = URLEncoder.encode(foo, "utf-8");

this method throws an UnsupportedEncodingException. Which is better:

/** @throws UnsupportedEncodingException umm...never
 */
public void myMethod() throws UnsupportedEncodingException {
   ...
   String encodedString = URLEncoder.encode(foo, "utf-8");
   ...
}

(forcing the caller to catch this himself) Or:

public void myMethod() {
   try {
     ...
     String encodedString = URLEncoder.encode(foo, "utf-8");
     ...
   catch(UnsupportedEncodingException e) {
      Logger.log("cosmic ray detected!");
   }

}

Or is there a more elegant way of handling exceptions which can’t really ever occur?

Answer 1

Never say never 😉

In the example above you could always catch the exception then throw a RuntimeException:

public void myMethod() {
   try {
      ...
      String encodedString = URLEncoder.encode(foo, "utf-8");
       ...
   } catch(UnsupportedEncodingException e) {
     throw new RuntimeException("This should not be possible",e);
   }

}

That way the caller isn’t forced to catch something you 99.999% sure will never happen, but in the crazy event that it does happen you still get an exception bubble up to a point where you’ll hopefully notice it and be able to quickly realize what’s changed and fix it.

HTH