试图缩短我的程序,以便不重复代码

Question

我正在编写一个程序,使用可观察的集合将膳食类型过滤到不同的类别.我正在使用枚举对膳食进行分类,并且我有三个单独的方法使用相同的代码,在单击各自的按钮时将它们分成新的集合.三种枚举类型是素食,肉类和鱼类.我有两个可观察的收藏品,餐和过滤餐.我试图创建另一种方法,然后传递类别作为参数,但我无法让它工作!任何帮助将不胜感激.

private void btnVegetarian_Click(object sender, RoutedEventArgs e)
    {
        filteredMeals = new ObservableCollection<Meal>();
        Meal newMeal = new Meal();

        for (int i = 0; i < meals.Count; i++)
        {
            newMeal = meals[i];
            if (newMeal.Category == MealCategory.Vegetarian)
            {
                filteredMeals.Add(newMeal);
            }
        }
        lbxMeals.ItemsSource = filteredMeals;
    }

    private void btnMeat_Click(object sender, RoutedEventArgs e)
    {
        filteredMeals = new ObservableCollection<Meal>();
        Meal newMeal = new Meal();

        for (int i = 0; i < meals.Count; i++)
        {
            newMeal = meals[i];
            if (newMeal.Category == MealCategory.Meat)
            {
                filteredMeals.Add(newMeal);
            }
        }
        lbxMeals.ItemsSource = filteredMeals;

    }

    private void btnFish_Click(object sender, RoutedEventArgs e)
    {
       filteredMeals = new ObservableCollection<Meal>();
        Meal newMeal = new Meal();

        for (int i = 0; i < meals.Count; i++)
        {
            newMeal = meals[i];
            if (newMeal.Category == MealCategory.Fish)
            {
                filteredMeals.Add(newMeal);
            }
        }
        lbxMeals.ItemsSource = filteredMeals;
    }

Answer 1

您需要创建一个采用MealCategory参数的新方法.将代码移动到那里,并为每个按钮单击处理程序传递适当的MealCategory.

然后代码可能如下所示:

private void btnVegetarian_Click(object sender, RoutedEventArgs e)
{
    FilterMeals(MealCategory.Vegatarian);
}

private void btnMeat_Click(object sender, RoutedEventArgs e)
{
    FilterMeals(MealCategory.Meat);
}

private void btnFish_Click(object sender, RoutedEventArgs e)
{
   FilterMeals(MealCategory.Fish);
}

private void FilterMeals(MealCategory category)
{
    filteredMeals = new ObservableCollection<Meal>();
    Meal newMeal = new Meal();

    for (int i = 0; i < meals.Count; i++)
    {
        newMeal = meals[i];
        if (newMeal.Category == category)
        {
            filteredMeals.Add(newMeal);
        }
    }
    lbxMeals.ItemsSource = filteredMeals;
}

一旦你有了工作,你可以尝试重构你的FilterMeals方法更短.您可以使用LINQ来表示过滤器,并且ObservableCollection构造函数有一个重载IEnumerable<T>,它可以简化它:

private void FilterMeals(MealCategory category)
{
    var filteredMeals = meals.Where(m => m.Category == category);
    lbxMeals.ItemsSource = new ObservableCollection<Meal>(filteredMeals);
}