Passing Optional.absent() values to methods concisely

Question

One problem with using Guava's Optional type as arguments of methods is that you can't simply write

// method declaration
public void foo(Optional<String> arg);

// compiler error
foo(Optional.absent());

due to type inference failing but instead have to add the type explicitly:

// real method call
foo(Optional.<String> absent());

How can I avoid it?

Answer 1

If you are dealing with a small set of Optional<> types (e.g., mostly strings or a handful of other types), just create some helper methods that bind the type argument for you:

public final class AbsentValues {
    public static Optional<String> absentString() {
        return Optional.<String>absent();
    }
}

You can even import these statically to result in cleaner code:

import static AbsentValues.*;

...

foo(absentString());

For less common Optional<> types, just specify the type argument explicitly. It may not be pretty, but it's correct.