Typecasting af ukendt subklasse

Enten kan du bare caste dit fpObject eller så skal du angive nogle generiske parametre.

Demo:

import java.lang.reflect.Constructor;

public class GenFun {
    private static P giveMe1(String clznam, int v) throws Exception {
        Class clz = Class.forName(clznam);
        Constructor ctor = clz.getConstructor(int.class);
        return (P)ctor.newInstance(v);
    }
    private static P giveMe2(String clznam, int v) throws Exception {
        Class<? extends P> clz = Class.forName(clznam).asSubclass(P.class);
        Constructor<? extends P> ctor = clz.getConstructor(int.class);
        return ctor.newInstance(v);
    }
    public static void main(String[] args) throws Exception {
        P o1 = giveMe1("C", 123);
        System.out.println(o1);
        P o2 = giveMe2("C", 123);
        System.out.println(o2);
    }
}

class P {
    protected int v;
    public P(int v) {
        this.v = v;
    }
    @Override
    public String toString() {
        return "P: " + v;
    }
}

class C extends P {
    public C(int v) {
        super(v);
    }
    @Override
    public String toString() {
        return "C: " + v;
    }
}

Av, det var en ordentlig omgang... Løste det selv for at par min siden til flg.:

public static FPClass getSubFP(String subClass, LinkedList<FuncPart> args) {
    try {
        Class<? extends FPClass> fpClass = Class.forName(subClass).asSubclass(FPClass.class);
        Constructor fpConstructor = fpClass.getConstructor(LinkedList.class);
        Object fpObject = fpConstructor.newInstance(new Object[]{args});
        return fpClass.cast(fpObject);
    } catch (Exception e) {
        System.out.println("Error... Could not find class");
    }   

    return null;
}

Du smider selv. bare et svar hvis du vil have point for din deltagelse.

Class<? extends FPClass> fpClass = Class.forName(subClass).asSubclass(FPClass.class);
        Constructor fpConstructor = fpClass.getConstructor(LinkedList.class);
        Object fpObject = fpConstructor.newInstance(new Object[]{args});
        return fpClass.cast(fpObject);

må kunne laves ligesom min kode 2:

        Class<? extends FPClass> fpClass = Class.forName(subClass).asSubclass(FPClass.class);
        Constructor<? extends FPClass> fpConstructor = fpClass.getConstructor(LinkedList.class);
        return fpConstructor.newInstance(new Object[]{args});

og et svar