Using exceptions with Google Guava

Question

What is the best pattern for using Google Guava with methods that should throw exceptions?

Let's say I have:

public Sting someMethod(Integer i) throws SomeException;

And I want to do:

List<String> s=Lists.transform(is,new Function<String, Integer>() {
       public String apply(Integer i) {
         return someMethod(i);
       }
     });

I couldn't do the above because of the exception. Is there any nice pattern for handling it?

Answer 1

Propagate the checked exception as a RuntimeException:

try {
    return someMethod(i);
} catch (SomeException e) {
    throw new RuntimeException(e);
}

EDIT: Since the transformed list is lazily evaluated, the exception won't be thrown until you access the list elements. You can force the evaluation by copying the transformed list into a new list, like:

s = new ArrayList<>(s);

You could wrap that in a try-catch block that catches RuntimeException and handles it however you want; your original SomeException instance can be obtained by calling getCause() on the RuntimeException. Or you could just let the RuntimeException bubble up.

Answer 2

You can use

public interface FunctionWithException<T, R, E extends Exception> {
    public R apply(T t) throws E;
}