如何在類數組中分配元素

Question

我有一個名為Tire的類，它有一個函數。 我在Car課上稱之為。 一輛汽車有 4 個輪胎，所以我需要在Car類中將輪胎聲明為一個數組，以便我可以調用在Tire類中實現的函數。 我該怎么做？

class Tire {
    public void pumpAir(int psi) {}
}

public class Car {
    private Tire[] tires = new Tire[4];
}

public static void main(String[] args) {

    Car car = new Car();

    car.tires ... // how to call 3rd tire and pump it?
}

Answer 1

一種選擇是為它創建一個吸氣劑：

public class Car {
    private Tire[] tires = new Tire[4];

    public Tire getTire(int i) {
        if (i >= 0 && i < tires.length) {
           return tires[i];
        }
        return null;
    }
}

在你的主要代碼中：

Tire t = car.getTire(3);
if (t != null) {
   t.pumpAir(42);
}

Answer 2

為輪胎創建一個 getter 並使用下標作為其私有訪問它。
或者將訪問說明符更改為public並使用下標運算符訪問它。

public class Car {
    private Tire[] tires = new Tire[4];

    public Tire getTire(int number) {
         if(number >= 0 && number < tires.length) {
              return tires[number];
         } else {
              return null;
         }
    }

}

public static void main(String[] args) {

    Car car = new Car();

    car.getTire(2) ... // how to call 3rd tire and pump it?
}

Answer 3

 public class Tire 
    {
        public void pumpAir(int psi) {
                 System.out.println("Tire number " + psi + " pumped.");
         }
    }



 public class Car {
        private Tire[] tires = new Tire[4];



 public Car()
    {
     for(int i=0;i<4;i++)
         this.tires[i]=new Tire(); 
    }

public Tire[] getTiers()

   {
     return tires;
   }
}

public static void main(String[] args) {



 Car car = new Car();

// how to call 3rd tire and pump it?
car.getTiers()[2].pumpAir(2 + 1);

}

Answer 4

最好的選擇是在 Car 類中創建一個 getter

public class Car 
{
    private Tire[] tires = new Tire[4];

    public Tire[] getTires() 
    {
        return tires;
    }
}

然后在主要，您可以通過以下方式訪問第三個輪胎

car.getTires()[2].pumpAir(someInt);