如何在Java的新类中创建特定类型的属性？

Question

I'm a Java Newbie and my Task is to create a taxi project with driver, passengers, seats and so on...

I am stuck in this point: Create a class called Taxi which represents a taxi. Because every taxi has a driver, every Taxi object should have a driver attribute (of type Human). Additionally, the Taxi can have passengers who are also represented by Human objects.

My already existing code:

public class Main {

public static void main(String[] args){

    Human human1 = new Human("Max", "Mustermann");

    // System.out.println(human1.getForename() + " " + human1.getName());
    System.out.println("This is " + human1 + ".");

    Taxi taxi1 = new Taxi();

    Human driver1 = new
}

}

public class Human {

private String name;
public String forename;

public Human(String forename, String name){
    this.name = name;
    this.forename = forename;
}

public String getName(){
    return name;
}

public String getForename(){
    return forename;
}

public String toString(){
    return this.forename + " " + this.name;
}
}




public class Taxi {


}

How to create driver and passengers of type human in the class Taxi?

Thank you.

Answer 1

Try something like:

public class Taxi {
    private Human driver;//Taxi has a driver
    public Taxi(Human driver) {
        this.driver = driver;
    }
}

---

// in main
Taxi taxi = new Taxi(human1);//pass that driver in constructor

Answer 2

I think that you should avoid mixing Human and Taxi concepts in your classes.
Human is really too broad. This is fine for biology or philosophy model domain not for taxi model domain.
You have some drivers ? Create a Driver class.
You have some passengers ? Create a Person or a Passenger class.

Separating concepts allow to settle things as the domain is.

Then provide methods in Taxi to fulfill your requirements :

• having a driver
• adding/removing passengers

For example :

public class Taxi {
    private Driver driver;
    private List<Passenger> passengers = new ArrayList<>();

    public Taxi(Driver driver) {
        this.driver = driver;
    }

    public addPassenger(Passenger passenger){
        this.passengers.add(passenger);
    }

    public removePassenger(Passenger passenger){
        this.passengers.remove(passenger);
    }
}

Here the Taxi instance may only be "driven" by a Driver instance and it may "accept" only Passenger instances.
If you have only the Human class, you are stuck as anybody may drive a taxi.

If the Driver may also be a Passenger, you may replace the Passenger class by a Person class.