Creating a personal exception class.

We're supposed to create a program for a class wherein it accepts an input for an age, then if the age is less than 0 throws an exception and stops the program. I cannot figure out how exception classes work for the life of me. Any help on where I'm going wrong? Thanks!

Code:

---

import java.util.Scanner;

public class A {


        public static void checkAge(int age) throws Exception{
                if(age < 0){
                        ageException b = new ageException("Invalid.");
                }
        }
       
        public static void main(String[] args) throws Exception {
                A a = new A();
                Scanner keyboard = new Scanner(System.in);
                System.out.print("Enter your age: ");
                int age = 0;
                try{
                        age = keyboard.nextInt();
                        checkAge(age);
                }
                catch (ageException b) {
                        System.out.println(b.v);
                }
                        System.out.println("Thanks. You say you are "+ age + " years old.");
        }

}

---

Exception:

Code:

---


public class ageException extends Exception {
       
        String v;

        public ageException(){
               
        }
        ageException(String z){
                String v = z;
        }
       
        public static void main(String[] args) {
               
        }

}

---

Your overloaded constructor on line 8 is missing the the scope - it should also be public. In your checkAge method, you need to throw a new exception:

Code:

---

throw new ageException("My message here");

---

Also, this is just a style note (but an important one), your class names should never start with a lowercase letter - lowercase is reserved for methods, variables, and key words.