Java: how to convert a List<?> to a Map<String,?> [duplicate]

Answer 1

Avoid reflection like the plague.

Unfortunately, Java's syntax for this is verbose. (A recent JDK7 proposal would make it much more consise.)

interface ToString {
    String toString(T obj);
}

public static  Map stringIndexOf(
    Iterable things,
    ToString toString
) {
    Map map = new HashMap();
    for (T thing : things) {
        map.put(toString.toString(thing), thing);
    }
    return map;
}

Currently call as:

Map map = stringIndexOf(
    things,
    new ToString() { public String toString(Thing thing) {
        return thing.getSomething();
    }
);

In JDK7, it may be something like:

Map map = stringIndexOf(
    things,
    { thing -> thing.getSomething(); }
);

(Might need a yield in there.)