排序自定义类字典C＃ [英] Sorting custom class dictionary C#

问题描述

我有一个嵌套的公共类KeyCountMap

I have a nested public class KeyCountMap

public KeyCountMap<T>  
{ 
   private IDictionary<T, MutableInt> map = new Dictionary<T, MutableInt>();
   public KeyCountMap()
   { }

   public KeyCountMap(Type dictionaryType)
   {
      if (!typeof(IDictionary<T, MutableInt>).IsAssignableFrom(dictionaryType))
      {
         throw new ArgumentException("Type must be a IDictionary<T, MutableInt>", "dictionaryType");
      }
      map = (IDictionary<T, MutableInt>)Activator.CreateInstance(_dictionaryType);
   }  

   public HashSet<KeyValuePair<T, MutableInt>> EntrySet()
   {
      return map.ToSet();
   }  
   //... rest of the methods...
}

要以值的降序排列地图中的值，如果我们使用Java，我们可以将方法写为：

To sort out the values in map in descending order of values, if we use Java we can write method as:

public static <T> KeyCountMap<T> sortMapByDescendValue(KeyCountMap<T> map) 
{
   List<Entry<T, MutableInt>> list = new LinkedList<>(map.entrySet());
   Collections.sort(list, new Comparator<Entry<T, MutableInt>>() 
   {
      @Override
      public int compare(Entry<T, MutableInt> o1, Entry<T, MutableInt> o2)  
      {
         return (-1) * (o1.getValue().get()).compareTo(o2.getValue().get());
      }
   });

   KeyCountMap<T> result = new KeyCountMap<T>();
   for (Entry<T, MutableInt> entry : list) 
   {
      result.put(entry.getKey(), entry.getValue());
   }
   return result;
}

如果我们使用C＃，我们可以将方法定义为：

If we use C#, we can defined method as:

public static KeyCountMap<T> SortMapByDescendValue<T>(KeyCountMap<T> map)
{
   List<KeyValuePair<T, MutableInt>> list = new List<KeyValuePair<T, MutableInt>>(map.EntrySet());  
   // map.EntrySet() returns of type HashSet<KeyValuePair<T, MutableInt>>  

   list = list.OrderByDescending(x => x.Value).ToList();

   KeyCountMap<T> result = new KeyCountMap<T>();
   foreach (KeyValuePair<T, MutableInt> entry in list)
   {
      result.Put(entry.Key, entry.Value);

   }
   return result; 
}

此方法是否正常工作，或者有必要覆盖 CompareTo（）方法（这里不用）排序？

Will this method work or is it necessary to override CompareTo() method (not used here) for sorting?

编辑

public class MutableInt
{
   internal int _value = 1; // note that we start at 1 since we're counting

   public void Increment()
   {
      _value++;
   }

   public void Discrement()
   {
      _value--;
   }

   public int Get()
   {
      return _value;
   }
}

推荐答案

字典（哈希表）没有订单。尝试通过控制插入顺序来排序哈希集不会奏效。如果您想订购，请勿使用字典作为后备店。

Dictionaries (hashtables) don't have an order. Trying to order a hashset by controlling the order of insertion just won't work. If you want ordering, don't use a dictionary as your backing store.

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