Question

我有这种代码的和平，并希望知道如何通过循环来使它更优雅。试图将列表和适配器放在一个对象数组中，但我无法用它调用.size()。

所以从这个：

int breakfastIndex = //get index.
if(breakfastIndex != -1 && breakfastFoodList.size() > breakfastIndex) {
    breakfastFoodList.remove(breakfastIndex);
    breakfastAdapter.notifyItemRemoved(breakfastIndex);
}

int lunchIndex = intent.getIntExtra("position", -1);
if(lunchIndex != -1 && lunchFoodList.size() > lunchIndex) {
    lunchFoodList.remove(lunchIndex);
    lunchAdapter.notifyItemRemoved(lunchIndex);
}

int dinnerIndex = intent.getIntExtra("position", -1);
if(dinnerIndex != -1 && dinnerFoodList.size() > dinnerIndex) {
    dinnerFoodList.remove(dinnerIndex);
    dinnerAdapter.notifyItemRemoved(dinnerIndex);
}

int snackIndex = intent.getIntExtra("position", -1);
if(snackIndex != -1 && snackFoodList.size() > snackIndex) {
    snackFoodList.remove(snackIndex);
    snackAdapter.notifyItemRemoved(snackIndex);
}

对此：

for(int i = 0; i < 4; i++) {
    int index = //get index.
    if(index != -1 && foodList[i].size() > index) {
        foodList[i].remove(index);
        adapter[i].notifyItemRemoved(index);
    }
}

Answer 1

你可以制作两个数组

List[] lists = {breakfastFoodList,...};
ArrayAdapter[] adapters = {breakfastAdapter,...};

然后，你写的那个循环看起来很好。

但是，如果您尝试一次性删除所有餐点，我觉得您应该存储一个列表，然后得到其余的

例如，

public class DailyMeal {
    Meal breakfast, lunch, dinner, snack;
}

然后，为您的列表

// In the Activity 
private List<DailyMeal> meals;
public List<Meal> getBreakfasts();  // return list of all  breakfasts
public List<Meal> getLunches();
// etc.

当您从膳食列表中删除DailyMeal对象时，您将自动删除每个Meal对象，以及＃34; day＆＃34;

Answer 2

有些人指出我的代码包含一个错误，事后看来这似乎是我的代码看起来“难看”的原因。

我决定使用一个简单的开关。

int index = intent.getIntExtra("position", -1);
String mealType = intent.getStringExtra("mealType");

switch(mealType) {
    case "BREAKFAST":
        if(index != -1 && breakfastFoodList.size() > index) {
            breakfastFoodList.remove(index);
            breakfastAdapter.notifyItemRemoved(index);
        }
    break;
    case "LUNCH":
        if(index != -1 && lunchFoodList.size() > index) {
            lunchFoodList.remove(index);
            lunchAdapter.notifyItemRemoved(index);
        }
        break;
    case "DINNER":
        if(index != -1 && dinnerFoodList.size() > index) {
            dinnerFoodList.remove(index);
            dinnerAdapter.notifyItemRemoved(index);
        }
        break;
   case "SNACK":
        if(index != -1 && snackFoodList.size() > index) {
            snackFoodList.remove(index);
            snackAdapter.notifyItemRemoved(index);
        }
        break;
}

如何循环自定义列表？

2 个答案: