Subclass constructors - Why must the default constructor exist for subclass constructors?

Question

Given a random class:

public class A {
    public T t;

    public A () {}  // <-- why is this constructor necessary for B?
    public A (T t) {
         


        

Answer 1

You may use your own constructor in A, but you have to call it explicitly from the B's constructor, e.g.:

public B(Integer i) {
  super(i);
  ...
}

If you don't do that, the compiler will attempt to instantiate A itself, by calling its default constructor.