Java主要方法中的调用方法

Question

I have a question regarding to using method in main class, here is my code for a Race class:

import java.util.ArrayList;


public class Race {

    private ArrayList<Car>cars;


    public Race(){
         cars = new ArrayList<Car>();
    }

    public void addCars(Car car){
        cars.add(car);
    }
}

The above is what I have done to make an arraylist for the cars that I am ready to put in by using a main method in another class:

public class Test {

    public static void main(String[] args) {
        Car toyota = new Car("Toyota",1.0,1.0,2.0,2.0);
        cars.addCars(toyota);
    }
}

However, it has error in the last line, it shows "cars cannot be resolved",I am not sure how should I fix it, maybe writing a getter method in the Race class?

Answer 1

Create an instance of race and call addCars

Race race = new Race();
race.addCars(toyota);

Answer 2

cars does not exist in that context, you might want to stick to the convention on having lowercase variable names, as well.

Change your Test class to something similar to this:

public class Test {
    public static void main(String[] args) {
        Race race = new Race();
        Car toyota=new Car("Toyota",1.0,1.0,2.0,2.0);
        race.addCars(toyota);
    }
}

You want to add cars to the race , not cars (which does not exist). To add cars to a race, you first need to make one.

By adding cars to the race, it will internally add it to the cars list. (Because you made it so) You problem is basically that you are trying to use a variable that is outside the scope. (Somewhere else, basically)

Since I don't know your exact problem, I can't really help you further, but you might want to save the race in a field rather than a local variable, it all depends on what you want to do.