java.lang.NoSuchMethodException: main [class [Ljava.lang.String;]

Question

I don't know what is wrong with the code below when I carefully follow the module given to me. pls, teach me why I'm getting that error. I'm totally a newbie on java while my professor not replying to me.

  public class Member{
  String name;
  int age;
  String number;
  String address;
  int salary;

  public void printSalary(){
    System.out.println(salary);
  }

}

class Employee extends Member{
  String specialization;
}

class Manager extends Member{
  String department;
}

class Ans{
  public static void main(String[] args){
    Employee e = new Employee();
    e.name = "Lado";
    e.age = 21;
    e.number = "0919467670";
    e.address = "Tunasan";
    e.salary = 10000;
    e.specialization = "Computer Coding";

    Manager m = new Manager();
    m.name = "Lala";
    m.age = 23;
    m.number = "09216t767";
    m.address = "Tunasan";
    m.salary = 0;
    m.department = "CITS Office";
  }
  

Answer 1

// Remove "public"
 class Member{
  String name;
  int age;
  String number;
  String address;
  int salary;

  public void printSalary(){
    System.out.println(salary);
  }

}

class Employee extends Member{
  String specialization;
}

class Manager extends Member{
  String department;
}

// Add "public", don't forget that the name of this java file must be "Ans.java"
public class Ans{
  public static void main(String[] args){
    Employee e = new Employee();
    e.name = "Lado";
    e.age = 21;
    e.number = "0919467670";
    e.address = "Tunasan";
    e.salary = 10000;
    e.specialization = "Computer Coding";

    Manager m = new Manager();
    m.name = "Lala";
    m.age = 23;
    m.number = "09216t767";
    m.address = "Tunasan";
    m.salary = 0;
    m.department = "CITS Office";
  }