Having just read the
NullPointerException-IllegalArgumentException-AssertionError thread, I
was just wondering if my use of AssertionError in one case was valid.
This is a very pared-down interface of the code:

import java.util.*;

public final class ClassPool {
    public interface SourceHandler {
        public boolean hasClass(String name);
    }

    private static List<SourceHandler> handlers =
        new LinkedList<SourceHandler>();

    static {
        // add a few handlers to the list...
        handlers.add(new SourceHandler() {
            public boolean hasClass(String name) {
                return true;
            }});
        // This is not really an anonymous inner class, but it is the
        // best way for me to make it compilable
    }

    // The user can add handlers but can never remove them.
    public static void addHandler(SourceHandler handler) {
        handlers.add(0, handler);
    }

    // Edited for simplicity
    public static void getClass(String name) {
        for (SourceHandler handler : handlers) {
             if (handler.hasClass(name))
                 return; // Use this handler as the class
        }
        // Since our last handler claims to handle everything, we should
        // never get here.
        throw new AssertionError();
    }
}

Where I throw the assertion error explicitly, I want to put an `assert
false;' statement in (with a comment, of course), but then I would need
to insert a `return null;' at the end of the method, which would
invalidate the method contract which forbids null as a result but
assertions may not be on.

Is it more appropriate to put a RuntimeException or other type of error
instead of using an AssertionError here?