car.java

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

public class Main 
{
 public static void main(String[] args)
 {
 Car car1 = new Car("audi", "blau");
 Car car2 = new Car("opel", "rot");

 car1.assignDriver("helmut", "lol");

 int anzahlCars = Integer.MAX_VALUE;
 System.out.println("Vorher: " + anzahlCars);

 List<Car> carList = new ArrayList<Car>();

 carList.add(car1);
 carList.add(car2);

 Car.showCars(carList);
 System.out.println("Nachher: " + Car.GesammtAnzahl(anzahlCars));
 }
}


public class Car
{
 private final String name;
 private final String color;
 public static int anzahl = 0;

 public Car(String name, String color)
 {
 this.name = Objects.requireNonNull(name, "name cannot be null");
 this.color = Objects.requireNonNull(color, "color cannot be null");
 anzahl++;
 }

 public void assignDriver(String license, String location)
 {
 Objects.requireNonNull(license, "license can not be null");
 Objects.requireNonNull(location, "license can not be null");
 }

 public String getCarName()
 {
 return name;
 }

 public static void showCars(List<Car> carList)
 {
 for (Car car : carList)
 {
 System.out.println(car.getCarName());
 }
 }

 public static int GesammtAnzahl(int x)
 {
 return x - anzahl;
 }
}