Parent Class Error in Java

[shivam_bhatele]

Hello Everyone, I am working on a java project and getting some errors which I mentioned below. I have this class, Person:

public class Person{
  String firstname;
  String lastname;

  public Person(String fname, String lname){

  }
  public String toString(){

  }
}

And this subclass, Student:

public class Student extends Person{
  Student(){
    super();
  }
  int studentID;
  int level;

  public Student(String fName, String lName, int gLevel){

  }
  public int getLevel(){

  }
  public String toString(){

  }
}

When I compile this code on Interviewbit, I get the error:

cannot find symbol 
symbol  : constructor Person() 
location: class Person

I am confused what the problem is. It’s my understanding that the use of the super() constructor should resolve this problem, and that it’s not even necessary in the code but I’m continuing to get this error.

[yayaya (Ya Ya)]

Because Person has no defaut constructor. public Person(String fname, String lname){} has overwritten defaut constructor. Defaut constructor is public Person(){}.

super() (without parameter) calls to method public Person(){} but it doesn’t exist.

You can view this topic with google translate.

Tại sao mọi class con cần gọi đến default constructor của class cha?

Không phải gọi đên default của class cha. Mà bơi vì Child không có construcctor, nên nó sẽ tạo ngầm default Child() { super(); } em mở file .class lên sẽ thấy nó tạo ra contructor như thế. Mà supper của Child là Parrent, mà parrent hiện tại không có contrunsctor Parrent(), nên lỗi là đúng rồi.

and these 3 articles

Does creating an instance of a subclass automatically run the superclass's constructor?

Does subclass use always super-class's default constructor?

https://www.quora.com/In-Java-does-every-object-constructor-automatically-call-super-in-object-before-its-own-constructors

[yayaya (Ya Ya)]

A question for you

public class Person {
	protected static int count = 0;
	String firstname;
	String lastname;

	public Person() {
		count++;
	}

	public Person(String fname, String lname) {
	}

	public String toString() {
		return null;
	}
}

---

class Student extends Person {

	public Student(String fName, String lName, int gLevel) {
		count++;
	}

	public int getLevel() {
		return 0;

	}

	public String toString() {
		return null;
	}

	public static void main(String[] args) {
		System.out.println(count);
		Student st = new Student(null, null, 0);
		System.out.println(count);
	}
}

What does the console output?