Question

I’ve got an object ‘Foo Action’ which is of type FooProcess (interface) [null object].
I want to initialize ‘Foo Action’ as an object of a subclass [FooOne or FooTwo] of FooProcess.

Using the Spring Framework, I am able to create ArrayList FooList (a list of names of subclasses of FooProcess), now I would like to initialize FooAction as one of the subclasses. (Given a parameter selected to define which class I want it to initialize as)

All subclasses of FooProcess have a constructor which accepts a String.

My problem is specifically on this line

    FooAction = component.getClass().getConstructor(f);

Full Method:

public FooProcess Load(String selected, String f) throws ClassCastException, InstantiationException, IllegalAccessException, ClassNotFoundException{
    ArrayList<String> FooList = new ArrayList<String>();
    final ClassPathScanningCandidateComponentProvider provider = new ClassPathScanningCandidateComponentProvider(true);
    provider.addIncludeFilter(new AssignableTypeFilter(FooProcess.class));
    for (BeanDefinition component : provider.findCandidateComponents("org.project.foomodule.systems")) {
        if(selected == component.getBeanClassName()){
        FooAction = component.getClass().getConstructor(f);
    } }
    return FooAction;
}

Answer 1

Look at this, it works the same

import java.awt.Rectangle;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

public class SampleInstance {

    public static void main(String[] args) {

        Rectangle rectangle;
        Class rectangleDefinition;
        Class[] intArgsClass = new Class[] { int.class, int.class };
        Integer height = new Integer(12);
        Integer width = new Integer(34);
        Object[] intArgs = new Object[] { height, width };
        Constructor intArgsConstructor;

        try {
            rectangleDefinition = Class.forName("java.awt.Rectangle");
            intArgsConstructor = rectangleDefinition
                    .getConstructor(intArgsClass);
            rectangle = (Rectangle) createObject(intArgsConstructor, intArgs);
        } catch (ClassNotFoundException e) {
            System.out.println(e);
        } catch (NoSuchMethodException e) {
            System.out.println(e);
        }
    }

    public static Object createObject(Constructor constructor,
            Object[] arguments) {

        System.out.println("Constructor: " + constructor.toString());
        Object object = null;

        try {
            object = constructor.newInstance(arguments);
            System.out.println("Object: " + object.toString());
            return object;
        } catch (InstantiationException e) {
            System.out.println(e);
        } catch (IllegalAccessException e) {
            System.out.println(e);
        } catch (IllegalArgumentException e) {
            System.out.println(e);
        } catch (InvocationTargetException e) {
            System.out.println(e);
        }
        return object;
    }
}