When do superclasses not have a default constructor?

Question

According to the Java tutorial on constructors:

You don\'t have to provide any constructors for your class, but you must be careful when doing this.

Answer 1

And in the main method of a driver class you do

A obj1 = new A();

a default constructor will be created

There is nothing you can do in the main method of a driver to create a default constructor. If it is defined, you can use it; if it is not defined, you get a compile error.

So when will the superclass not have a no-argument constructor?

When it has other constructors, all of which taking some arguments. Here is an example:

class SuperA {
    public SuperA(String str) { ... }
    public SuperA(int num) { ... }
}

Above, SuperA has two constructors - one taking a String, and another one taking an int. Neither of them is default, because they take parameters.

If you make a derived class DerivedB extends SuperA and do not define any constructors, you would get a compile error.