Dead simple view injection

ViewInjector.java

import android.app.Activity;
import android.support.annotation.IdRes;
import android.view.View;

import java.lang.annotation.Annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Field;

/**
* Usage: 
* add as field:
* @ViewInjector.Inject(R.id.view_id)
* View view;
*
* in onCreate / getView / onCreateView
* ViewInjector.inject(this, viewRoot);
*/
public final class ViewInjector {

    public static void inject(Object object, Activity viewRoot) {
        injectAsObject(object, viewRoot);
    }

    public static void inject(Object object, View viewRoot) {
        injectAsObject(object, viewRoot);
    }

    private static void injectAsObject(Object object, Object viewRoot) {
        for (final Field field : object.getClass().getFields()) {
            for (final Annotation annotation : field.getDeclaredAnnotations()) {
                if (annotation instanceof Inject) {
                    final int resourceId = ((Inject) annotation).value();
                    final View view = findView(viewRoot, resourceId);
                    setView(object, field, view);
                    break;
                }
            }
        }
    }

    private static View findView(Object viewRoot, int resourceId){
        if(viewRoot instanceof Activity){
            return ((Activity)viewRoot).findViewById(resourceId);
        } else if (viewRoot instanceof View){
            return ((View)viewRoot).findViewById(resourceId);
        }
        throw new RuntimeException("viewRoot must be a Activity or View");
    }

    private static void setView(Object object, Field field, View view){
        try {
            field.set(object, view);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

    @Retention(RetentionPolicy.RUNTIME)
    @Target(ElementType.FIELD)
    public @interface Inject {
        @IdRes int value();
    }
}