如何将对象添加到数组中（如果该对象还不在数组中）

Question

我到处都找不到一个类似于我的问题的答案，在Java中。我使用的是数组，而不是数组列表。

每次在我的咖啡店下新的订单时，咖啡店必须添加到客户已经访问过的商店数组中，但它应该只出现一次，即使他们访问过两次说‘星巴克’。

我有一个main文件，一个CoffeeShop类，和一个Customer类，这三个文件都在OOP中协同工作。

secondCup.newOrder(bruno, latte); //bruno is a Customer object, latte is a Drink object.

public void newOrder(Customer c, Drink d)
{
    /* 
    double t = markUp*d.calculateCost();
    DrinkOrder o = new DrinkOrder(c, d, t);
    orders[pendingOrders++] = o;

    currentProfit += t - d.calculateCost();

    tracker[trackerSize++] = c;
    totalOrders++;
    */ //above is irrelevant 

    c.addStore(this); //Here is where im adding the store that called the 'newOrder()' method
}

我认为“this”应该是调用“.newOrder（）”的特定咖啡店，但大体上，当不同的商店调用newOrder（）时，让我们假设：

starBucks.newOrder(bruno, latte);

当我打印访问过的商店数组时，我会得到2个secondCups，而不是同时得到一个secondCups和一个star bucks（我认为这是因为我如何将我的CoffeeShop发送到addStore（）或者我如何将该商店添加到访问过的商店数组中）。

下面是我的方法，它应该检查存储区是否已经存在于数组中，如果不存在，则应该将其添加到数组中：

    public void addStore(CoffeeShop shop)
{
    size++;

    for (int i=0; i<size; i++)
    {
        if (visited[i] == null) //if the first position is null (which it will be, add their first shop visited
        {
            visited[i] = shop;
            break;
        }

        else if (visited[i].equals(shop)) //if if the index of the array equals the shop passed, then break the loop AKA dont add it to the array
        {
            break;
        }

        else //if none of the positions equal the shop, add it to the array
        {
            visited[i] = shop;
        }
    }
}

我尝试使用do while,如下所示,但得到的输出与上面的尝试完全相同：

for (int i=0; i<size; i++)
{
    do
    {
        visited[i] = shop; //complete atleast one action, because the customer hasnt visited anystore yet so the first store should always be added
    }
    while (!visited[i].equals(shop)); //add to the array as long as they're not equal

以下是我的输出：

Total coffee orders: 6

Swift, Taylor has visited:
Starbucks
Starbucks
Starbucks

Mars, Bruno has visited:
Second Cup
Second Cup

Ada, Lovelace has visited:
Second Cup

应该是这样的（泰勒光顾星巴克两次，但应该只加一次）：

Total coffee orders: 6

Swift, Taylor has visited:
Starbucks
Second Cup

Mars, Bruno has visited:
Starbucks
Second Cup

Ada, Lovelace has visited:
Second Cup

public void displayStoresVisited()
{
    for (int i=0; i<size; i++)
        System.out.println(visited[i].getName());
}

    for (int i=0; i<size; i++)
    {
        if (visited[i] == null)
        {
            visited[i] = shop;
            break;
        }

        else if (visited[i].equals(shop))
        {
            size -= 1;
        }

        else
        {
            continue;
        }
    }

Total coffee orders: 6

Swift, Taylor has visited:
Starbucks
Second Cup
Exception in thread "main" java.lang.NullPointerException
        at Customer.displayStoresVisited(Customer.java:105)
        at TestPhase4.main(TestPhase4.java:82)

Answer 1

int i=0;
while((i<size) && (!visited[i].equals(shop))){
  ++i;
}
if(i>=visited.length){
   //increase the size of your array here.
}
if(i >= size){
   visited[i] = shop;  
   size++;
}


/* get rid of this:
for (int i=0; i<size; i++)
{
    if (visited[i] == null)
    {
        visited[i] = shop;
        break;
    }

    else if (visited[i].equals(shop))
    {
        size -= 1;
    }

    else
    {
        continue;
    }
}
*/