如何从静态方法中获取总数

Question

好的,所以我已经发布了第一部分(我没有获得热狗机销售的正确输出)并获得了大量的帮助,但现在我无法想出从所有不同的展台返回正确的总数.我通过使用'this'关键字让支架增加,但我无法弄清楚如何让静态getTotal正确地增加所有支架.

public class HotDogStand {

    //instance variable declaration
    private int IDNumber;
    private int hotDogsSold=0;
    private static int totalSold=0;
    //constructor
    public HotDogStand(int ID, int sold)
    {
        this.IDNumber=ID;
        this.hotDogsSold=sold;
    }
    //sets ID for all the stands
    public void setID(int ID)
    {
        this.IDNumber=ID;
    }
    public int getID()
    {
        return IDNumber;
    }
    //invoked each time a stand makes a sale
    public void justSold()
    {
            this.hotDogsSold++;
            totalSold=hotDogsSold;
    }
    //gets the totals for the different stands
    public int getSold()
    {
        return this.hotDogsSold;
    }

    // returns total sales of all stands
    public static int getTotal()
    {
        return totalSold;
    }

}

和我的测试课

public class HotDogTest {
public static void main(String[]args){
    HotDogStand stand1=new HotDogStand(1, 1);
    HotDogStand stand2=new HotDogStand(2, 2);
    HotDogStand stand3=new HotDogStand(3, 7);

    stand1.getID();
    stand2.getID();
    stand3.getID();
    stand1.setID(1);
    stand2.setID(2);
    stand3.setID(3);
    stand1.justSold();
    stand2.justSold();
    stand3.justSold();
    stand1.justSold();
    stand1.justSold();
    stand1.justSold();
    stand3.justSold();

    System.out.println("Stand " + stand1.getID() + " sold " + stand1.getSold());
    System.out.println("Stand " + stand2.getID() + " sold " + stand2.getSold());
    System.out.println("Stand " + stand3.getID() + " sold " + stand3.getSold()); 

    System.out.println("The total amount of hotdogs sold by all the stands was "+HotDogStand.getTotal());

}

}

返回:第1站售出5第2站售出3第3站售出9所有看台售出的热狗总数为9

因此它正确地调用justSold方法并正确递增,但它只是从一个支架中拉出总数.

Answer 1

每次调用justSold()时都会更改totalSold,而不是根据需要递增它.即改变这个:

public void justSold()
{
        this.hotDogsSold++;
        totalSold=hotDogsSold;
}

对此:

public void justSold()
{
        this.hotDogsSold++;
        totalSold++;
}