Why we create abstract method insted of normal method? At the first place

Question

abstract class A {
abstract void display ();
}
class B extends A {
void display(){
System.out.println(" Why i am not created on the first place? ");
}
}
class Main{
public static void main (String[]ar){
A obj = new A();
obj.display();
}
}

Answer 1

In some cases, there's no common behavior for a method in the super class and you want each sub class to have its own implementation of that method, you'd make that method in super class abstract.