I am trying to intercept an Exception thrown by my algorithm in Java, and change the text to another language, and show it to the user. Is this possible in java?
Sorry by my English.
You can catch an exception, and then throw a new one of the same type (or a different type if you prefer). Then translate the message from the original exception and pass it into the new exception. Something like the following (not tested):
try {
// do something
}
catch (Exception e) {
throw new Exception(translate(e.getMessage()))
}
public String translate(String message) { /* translation code */ }
Update in response to comment:
If you can modify the application (and particularly if the application uses custom exceptions derived from a few base classes) then you might be able to modify these to retrieve translated messages (but if you could do that, you could build in the translated messages, or full internationalisation, from the start!).
Intercepting and replacing all Exceptions globally is probably not possible, although it looks like you can at least detect them globally using debug hooks - see this answer. It's conceivable that you could modify the Exception message on-the-fly using reflection, but this sounds pretty nasty.
One final possibility is to use Aspect-Oriented Programming (AOP) to compile-in extra behaviour around code that throws an exception (see this question, for example). You'd need to recompile the whole application using AOP tools though, and would probably still need to modify the application code a bit.