If you declare any constructor, what happens to the default no-argument constructor?

If you declare any constructor, what happens to the default no-argument constructor?

• A. The compiler does not generate a default no-argument constructor
• B. The compiler always generates a default no-argument constructor
• C. The compiler generates a default constructor with parameters
• D. You must manually create a no-argument constructor

Answer: (A)

When you declare any constructor, the language stops automatically providing a default no-argument constructor. The compiler only adds that default when you haven’t defined any constructors at all. If you want to create objects without arguments, you must define a no-argument constructor yourself. For example: class Widget { Widget(int size) { /* ... */ } } Without a no-argument constructor, new Widget() won’t compile. If you add one: class Widget { Widget() { /* default init */ } Widget(int size) { /* ... */ } } then new Widget() is allowed. So the default no-argument constructor is not generated once you declare any constructor; you must define it yourself if you need it.

When you declare any constructor, the language stops automatically providing a default no-argument constructor. The compiler only adds that default when you haven’t defined any constructors at all. If you want to create objects without arguments, you must define a no-argument constructor yourself.

For example:

class Widget {

Widget(int size) { /* ... */ }

}

Without a no-argument constructor, new Widget() won’t compile. If you add one:

class Widget {

Widget() { /* default init */ }

Widget(int size) { /* ... */ }

}

then new Widget() is allowed.

So the default no-argument constructor is not generated once you declare any constructor; you must define it yourself if you need it.