# Introduction

## Interfaces

Abstract class used to define object API.

Classes can then implement this API.

```
public interface Car {
    public void turn(blabla);
    blabla;
}
```

### Polymorphism

Most general interface is Object (like golangs interface{} ? ).

## Encapsulations

Hide internal details.
This can be done with getters and setters.

These getters and setters can then be used to to input validation.

## Private vs protected

Protected are accessible to subclasses which inherit from it.