collections/dictionary/0/prog.cs - A program working with Dictionary<Person,BankAccount>.

Lecture 12 - slide 27 : 36 Program 3

using System;
using System.Collections.Generic;

class DictionaryDemo{

  public static void Main(){

    IDictionary<Person, BankAccount> bankMap =                       
      new Dictionary<Person,BankAccount>(new PersonComparer());      

    // Make bank accounts and person objects
    BankAccount ba1 =  new BankAccount(0.01),  
                ba2 =  new BankAccount(0.02),  
                ba3 =  new BankAccount(0.03),
                ba4 =  new BankAccount(0.04);

    Person p1 = new Person("Kurt"),  
           p2 = new Person("Maria"),
           p3 = new Person("Francoi");

    ba1.Deposit(100); ba2.Deposit(200); ba3.Deposit(300);   
                                                            
    // Populate the bankMap: 
    bankMap.Add(p1, ba1);                                   
    bankMap.Add(p2, ba2);                                   
    bankMap.Add(p3, ba3);                                   
    ReportDictionary("Initial map", bankMap);

    // Print Kurt's entry in the map:
    Console.WriteLine("{0}\n", bankMap[p1]);                

    // Mutate Kurt's entry in the map
    bankMap[p1] = ba4;                                      
    ReportDictionary("bankMap[p1] = ba4;", bankMap);

    // Mutate Maria's entry in the map. PersonComparer crucial!
    ba4.Deposit(400);
    bankMap[new Person("Maria")] = ba4;                     
    ReportDictionary("ba4.Deposit(400);  bankMap[new Person(\"Maria\")] = ba4;", bankMap);

    // Add p3 yet another time to the map
    // Run-time error: An item with the same key has already been added.
/*  bankMap.Add(p3, ba1);
    ReportDictionary("bankMap.Add(p3, ba1);", bankMap); 
 */

    // Try getting values of some given keys
    BankAccount ba1Res = null,
                ba2Res = null;
    bool res1 = false,
         res2 = false;
    res1 = bankMap.TryGetValue(p2, out ba1Res);                        
    res2 = bankMap.TryGetValue(new Person("Anders"), out ba2Res);          
    Console.WriteLine("Account: {0}. Boolean result {1}", ba1Res, res1);   
    Console.WriteLine("Account: {0}. Boolean result {1}", ba2Res, res2);   
    Console.WriteLine();

    // Remove an entry from the map
    bankMap.Remove(p1);                                                    
    ReportDictionary("bankMap.Remove(p1);", bankMap);

    // Remove another entry - works because of PersonComparer
    bankMap.Remove(new Person("Francoi"));                                   
    ReportDictionary("bankMap.Remove(new Person(\"Francoi\"));", bankMap);   
  }

  public static void ReportDictionary<K, V>(string explanation,              
                                            IDictionary<K,V> dict){          
    Console.WriteLine(explanation);
    foreach(KeyValuePair<K,V> kvp in dict)
      Console.WriteLine("{0}: {1}", kvp.Key, kvp.Value);
    Console.WriteLine(); 
  }
}

public class PersonComparer: IEqualityComparer<Person>{                      

  public bool Equals(Person p1, Person p2){   
    return (p1.Name == p2.Name);                                             
  }                                                                          

  public int GetHashCode(Person p){
    return p.Name.GetHashCode();
  }
}