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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()
private final Map<String,T> map;
private EZMap(Map<String,T> _map, Function<Object,T>[] entries) {
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);
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;
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henrik242 commented Feb 8, 2017

Not bad! Here's a less evil, more compact, but slightly less pretty attempt:

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