A Case Using Java Reflection

java

We have a class Person:

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package com.reflection;

public class Person {
    private String name;
    private Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

We also have a class Student:

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package com.reflection;

public class Student {
    private String name;
    private Integer age;
    private String number;
    private String grade;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }
}

The class Person and Student have same fields name of type String and age of Type Integer. Therefore, we can set a student’s fields using a person’s counterpart fields:

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package com.reflection;

public class Main {
    public static void main(String[] args) {
        Person person = new Person();
        person.setName("Eric");
        person.setAge(24);

        Student student = new Student();
        student.setName(person.getName());
        student.setAge(person.getAge());
    }
}

A more efficient way is to use reflection:

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package com.reflection;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    public static void main(String[] args) throws InvocationTargetException, IllegalAccessException {
        Person person = new Person();
        person.setName("Eric");
        person.setAge(24);

        Student student = new Student();

        Class<? extends Person> personClass = person.getClass();
        Class<? extends Student> studentClass = student.getClass();

        Method[] personClassDeclaredMethods = personClass.getDeclaredMethods();
        Method[] studentClassDeclaredMethods = studentClass.getDeclaredMethods();

        for (Method personMethod : personClassDeclaredMethods) {
            if (personMethod.getName().contains("get")) {
                String setterName = "set" + personMethod.getName().substring(3);// e.g. getAge => setAge
                Object getterValue = personMethod.invoke(person);// i.e. person.getAge()
                for (Method studentMethod : studentClassDeclaredMethods) {
                    if (studentMethod.getName().equals(setterName)) {
                        studentMethod.invoke(student, getterValue);// i.e. student.setAge(getterValue)
                    }
                }
            }
        }
    }
}