What is Implicit constructors on Java

Question

Is it mandatory to call base class constructor in Java? In C++ it was optional, so I am asking this.

When I extend ArrayAdapter, I get this error:

Answer 1

It's not necessary to call the no-args constructor of super class. If you want to call a constructor with args, user super keyword like show below:

super(arg1, ...);

Answer 2

The no-args constructor is called implicitly if you don't call one yourself, which is invalid if that constructor doesn't exist. The reason it is required to call a super constructor is that the superclass usually has some state it expects to be in after being constructed, which may include private variables that can't be set in a sub-class. If you don't call the constructor, it would leave the object in a probably invalid state, which can cause all kinds of problems.