Pretty Map Literals for Java 8

public class EZMap<T> {
    public static void main(String[] args) {
            Map<String,Object> m = hashMap(
                    bob -> 5,
                    TheGimp -> 8,
                    incredibleKoolAid -> "James Taylor",
                    heyArnold -> new Date()
            );
            System.out.println(m);
    }

    private final Map<String,T> map;

    private EZMap(Map<String,T> _map, Function<Object,T>[] entries) {
        map=_map;
        for( Function<Object,T> entry: entries ) {
            final Method m;
            try {
                m = entry.getClass().getDeclaredMethod("apply", Object.class);
            } catch (NoSuchMethodException nsme ) { throw new RuntimeException(nsme); }
            final Parameter p = m.getParameters()[0];
            final String key = p.getName();
            final T value = entry.apply(null);
            map.put(key,value);
        }
    }

    public static <R> Map<String,R> hashMap(Function<Object, R>... entries) {
        return new EZMap<R>(new HashMap<>(), entries).map;
    }

    public static <R> Map<String,R> treeMap(Function<Object, R>... entries) {
        return new EZMap<R>(new TreeMap<>(), entries).map;
    }

}

Your code is pretty similar to my all time favourite support function for simple array creation, so I'll just leave this here:

public static <T> T[] array(T...entries) {
    return entries;
}

With what java compiler does this actually work?

This only works in Java8 which supports lambdas.

For some reason I don't get my parameter names, I get "arg0" instead.

Great idea - but I'm having the same arg0 problem as @jagwire - see discussion on reddit: http://www.reddit.com/r/java/comments/2360is/pretty_map_literals_for_java_8/

Pretty, but expensive.

The trick is how to get the key from the lambda, looks good.

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Not bad! Here's a less evil, more compact, but slightly less pretty attempt: http://stackoverflow.com/a/39510693/13365