When do you need to explicitly call a superclass constructor?

Question

So say I have a subclass that extends a superclass. In what scenarios do I need to explicitly type `super()` to get the superclass constructor to run? I'm looking at an example in a book about abstract classes and when they extend it with a non-abstract subclass, the subclass's default constructor is blank and there's a comment that says the superclass's default constructor will be called. At the same time I've also seen instances on here where someone's problem was not explicitly calling `super()`. Is the distinction from calling the superclass's default/non-default constructor from the subclass's default/non-default constructor?

Accepted Answer

You never need just

```
super();
```

That's what will be there if you don't specify anything else. You only need to specify the constructor to call if:

- You want to call a superclass constructor which has parameters

- You want to chain to another constructor in the same class instead of the superclass constructor

You claim that:

At the same time I've also seen instances on here where someone's problem was not explicitly calling super().

Could you give any examples? I can't imagine how that's possible...

When do you need to explicitly call a superclass constructor?

Solution

Problem