Java class

class look for nouns in the process
methods: verbs
each method is the responsibility of a single class

  private int numberOfPassengers;

    public void addPassenger(int n)
    {
        if (numberOfPassengers + 1 < numberOfSeats)
        {
          numberOfPassengers++;
        }
    }
    public int getPassengerCount()
    {
        return numberOfPassengers;
    }

import java.util.ArrayList;

public class Car
{
    private int numberOfSeats;
    private ArrayList passengers;
    private int numberOfPassengers;


    public Car(int numberOfSeats)
    {
        this.numberOfSeats = numberOfSeats;
        passengers = new ArrayList();
    }

   /**
    *  Adds a passenger to this car, provided that there is space.
    *  @param name the name of the passenger
    */
    public void addPassenger(String name)
    {
        if(getPassengerCount() + 1 < numberOfSeats)
        {
          passengers.add(name);
        }
        
    }

    public int getPassengerCount()
    {
        return passengers.size();
    }

    public String getPassengerList()
    {
        return passengers.toString();
    }
    
}