Class<?> arrayListClass = Class.forName("java.util.ArrayList"); Class<?> arrayListClass = Class.forName("java.util.ArrayList"); Method addMethod = arrayListClass.getDeclaredMethod("add", Object.class); ArrayList<Object> arrayList = new ArrayList<>(); addMethod.invoke(arrayList, "Hello"); Class<?> arrayListClass = Class.forName("java.util.ArrayList"); Field elementDataField = arrayListClass.getDeclaredField("elementData"); ArrayList<Object> arrayList = new ArrayList<>(); Object[] elementData = (Object[]) elementDataField.get(arrayList); elementDataField.set(arrayList, new Object[20]); Class<?> arrayListClass = Class.forName("java.util.ArrayList"); ArrayList<Object> arrayList = (ArrayList<Object>) arrayListClass.newInstance(); Class<?> myClass = Class.forName("com.myapp.MyClass"); MyClassAnnotation classAnnotation = myClass.getAnnotation(MyClassAnnotation.class); Method myMethod = myClass.getDeclaredMethod("myMethod"); MyMethodAnnotation methodAnnotation = myMethod.getAnnotation(MyMethodAnnotation.class); Field myField = myClass.getDeclaredField("myField"); MyFieldAnnotation fieldAnnotation = myField.getAnnotation(MyFieldAnnotation.class); methodAnnotation.setValue("New Value");