Dictionaries are so commonplace that it's no wonder that each of the languages we are examining supports them with concrete implementations. Here are some examples of initializing a dictionary, adding a few key/value pairs to the collection, and then removing one of those pairs from the collection.

C#

C# provides a concrete implementation of the dictionary data structure through the Dictionary<TKey, TValue> class. Since this class is generic, the caller may define the types used for both the keys and values. Here is an example:

    Dictionary<string, int> dict = new Dictionary<string, int>(); 

This example initializes a new dictionary where the keys will be string types, and the values will be int types:

    dict.Add("green", 1); 
    dict.Add("yellow", 2);  
    dict.Add("red", 3); 
    dict.Add("blue", 4); 
    dict.Remove("blue"); 
    Console.WriteLine("{0}", dict["red"]); 

    // Output: 3 

Java...