public static void main(String[] args) {
        Class<Person> personClass = Person.class;
        Constructor<Person> constructor;

        try {
            constructor = personClass.getDeclaredConstructor(ReflectionAPI.Person.class);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        }

        PersonData personData = constructor.getAnnotation(PersonData.class);
        String[] names = personData.persons();
        int [] ages = personData.ageOfPersons();
        for (int i = 0; i < names.length; i  ) {
            System.out.println(names[i]);
            System.out.println(ages[i]);
        }
    }

I dont know what to do I tried different things, I think the problem is the Parameter in the getDEclaredConstructor. Please help!

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Discover
public class Person {

    private String name;
    private int age;

    @PersonData(persons = {"Fritz", "Hans", "Peter"}, ageOfPersons = {69, 86, 99})
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

}

Here's the Person class. I dont see whats wrong, Im still learning so please have mercy!

CodePudding user response：

The arguments to getDeclaredConstructor are the types of the parameters for the constructor. So here, your code would be looking for something like

public Person(Person arg) {
   ...
}

If your class doesn't have a constructor like that, you'll get the NoSuchMethodException.

Based on your Person class, you might want something like

personClass.getDeclaredConstructor(String.class, int.class);