Why does ClassCastException occur this code?

import java.util.Arrays;
class Person {
    String name;
    int age;
    public Person(String name, int age) {
        this.name = name; this.age = age;
    }
    @Override
    public String toString() {
        return name + ": " + age;
    }
}
class ObjSort {
    public static void main(String[] args) {
        Person[] arr = new Person[3];
        arr[0] = new Person("Stephen", 31);
        arr[1] = new Person("Richard", 24);
        arr[2] = new Person("Bachman", 50);
        Arrays.sort(arr);
        for (Person p : arr)
            System.out.println(p);
    }
}

I want to sort in descending order by age.
When I run it, the problem occurs with Arrays.sort(arr);
How should I fix the Person class?

Exception in thread "main" java.lang.ClassCastException: class Person cannot be cast to class java.lang.Comparable (Person is in unnamed module of loader 'app'; java.lang.Comparable is in module java.base of loader 'bootstrap')
    at java.base/java.util.ComparableTimSort.countRunAndMakeAscending(ComparableTimSort.java:320)
    at java.base/java.util.ComparableTimSort.sort(ComparableTimSort.java:188)
    at java.base/java.util.Arrays.sort(Arrays.java:1040)
    at ArrayObjSort.main(ArrayObjSort.java:25)

Added error log.

>Solution :

The Arrays.sort() is expecting an array of objects that are comparable.

You need to make your Person class comparable.

class Person implements Comparable<Person> {
    String name;
    int age;
    public Person(String name, int age) {
        this.name = name; this.age = age;
    }
    @Override
    public String toString() {
        return name + ": " + age;
    }

    public int compareTo(Person p){
        return name.compareTo(p.name);
    }
}