Reflection in factory design patterns in Java or C#

Question

I came across a term called reflection. It is a feature commonly used in factory design patterns. I had a hard time understanding the concept because I’m still learning how to p

Answer 1

Java version for this question

Code:

public class TestReflectionFactoryDesign {

    public static void main(String[] args) throws Exception {
        Person student = PersonFactory.getPersonWithFullQualifiedClassName("com.test.reflectionFactoryDesign.Student");
        student.say();
        Person teacher = PersonFactory.getPersonWithClass(Teacher.class);
        teacher.say();
        Person student2 = PersonFactory.getPersonWithName("student");
        student2.say();
    }
}

class Student implements Person {
    @Override
    public void say() {
        System.out.println("I am a student");
    }
}

class Teacher implements Person {
    @Override
    public void say() {
        System.out.println("I am a teacher");
    }
}

interface Person {
    void say();
}

class PersonFactory {
    // reflection, by full qualified class name
    public static Person getPersonWithFullQualifiedClassName(String personType) throws Exception {
        Class personClass = Class.forName(personType);
        return getPersonWithClass(personClass);
    }

    // reflection, by passing class object
    public static Person getPersonWithClass(Class personClass) throws Exception {
        return (Person) personClass.newInstance();
    }

    // no reflection, the ordinary way
    public static Person getPersonWithName(String personType) {
        if (personType.equalsIgnoreCase("STUDENT")) {
            return new Student();
        } else if (personType.equalsIgnoreCase("TEACHER")) {
            return new Teacher();
        }

        return null;
    }
}

Output:

I am a student
I am a teacher
I am a student