Java 8 Lambda function that throws exception?

Question

I know how to create a reference to a method that has a String parameter and returns an int, it\'s:

Function         


        

Answer 1

Disclaimer: I haven't used Java 8 yet, only read about it.

Function doesn't throw IOException, so you can't put any code in it that throws IOException. If you're calling a method that expects a Function, then the lambda that you pass to that method can't throw IOException, period. You can either write a lambda like this (I think this is the lambda syntax, not sure):

(String s) -> {
    try {
        return myMethod(s);
    } catch (IOException ex) {
        throw new RuntimeException(ex);
        // (Or do something else with it...)
    }
}

Or, if the method you're passing the lambda to is one you wrote yourself, you can define a new functional interface and use that as the parameter type instead of Function:

public interface FunctionThatThrowsIOException {
    O apply(I input) throws IOException;
}