我来到这个网站搜索 Dictionary 中的对象比较,我发现重写 GetHashCode 和 Equals 是在 C# 中进行对象比较的必须条件。
这是我一直试图使用 FOREACH 迭代方法解决的一段代码。但由于性能问题,我的老板说要在不使用任何迭代的情况下执行相同的操作(可能通过使用 containskey 或 containsvalue 方法)。非常欢迎任何帮助..
public class employee
{
public string empname { get; set; }
public string location { get; set; }
public double kinid { get; set; }
public double managerKin { get; set; }
public override bool Equals(object obj)
{
return base.Equals(obj);
}
public override int GetHashCode()
{
return base.GetHashCode();
}
}
public class manager
{
public string managername { get; set; }
public double kinid { get; set; }
public override int GetHashCode()
{
return 17 * managername.GetHashCode() + kinid.GetHashCode();
}
}
public class program
{
public static void Main()
{
employee emp = new employee();
employee emp2 = new employee();
manager mng = new manager();
manager mng2 = new manager();
emp.empname = "Deepak";
emp.location = "Pune";
emp.kinid = 36885;
emp.managerKin = 007;
emp2.empname = "Astha";
emp2.location = "Pune";
emp2.kinid = 30000;
emp2.managerKin = 007;
mng.kinid = 007;
mng.managername = "Gaurav";
mng2.kinid = 001;
mng2.managername = "Surya";
Dictionary<employee, manager> relations = new Dictionary<employee, manager>();
relations.Add(emp, mng);
relations.Add(emp2, mng2);
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("The Manager details are :");
foreach (var element in relations)
Console.WriteLine(" \n KINID : {0} \n Manager'sName : {1}",element.Value.kinid, element.Value.managername);
Console.WriteLine("Enter the details of the manager..");
Console.ForegroundColor = ConsoleColor.Gray;
Console.Write("\nManager's Kin : ");
double mkin = Convert.ToDouble(Console.ReadLine());
Console.Write("Manager's Name : ");
string mname = Console.ReadLine();
manager mng1 = new manager();
mng1.kinid = mkin;
mng1.managername = mname;
int hashvalue = 17 * mname.GetHashCode() + mkin.GetHashCode();
#region BY USING FOREACH LOOP
int i = 0;
foreach (var element in relations)
{
if (element.Value.GetHashCode() == hashvalue)
{
i += 1;
if (i == 1)
{
Console.WriteLine("The Following employees report to the Manager : {0}", mname);
}
Console.WriteLine(element.Key.empname + " " + element.Key.kinid + " " + element.Key.location + " " + element.Key.managerKin);
}
}
if (i == 0)
{
Console.WriteLine("sorry the manager's details you entered \"{0}\" \"{1}\" does not exist in our database..", mng1.managername, mng1.kinid);
}
#endregion
Console.ReadLine();
}
}
为了使用 ContainsKey 或 ContainsValue 关键字在字典中搜索对象,编译器使用两个隐式函数,即 GetHashCode() 和 Equals()。因此,当我们有一个要比较的对象时,我们需要重写这两个方法!
这是代码
#region USING DICTIONARY TO STORE CLASS OBJECTS (check employee existence and print manager's name)
public class employee
{
public string empname { get; set; }
public string location { get; set; }
public double kinid { get; set; }
public double managerKin { get; set; }
//public override bool Equals(object obj) // ANY OF THE TWO EQUALS METHOD WORKS.
//{
// employee otheremployee;
// otheremployee = (employee)obj;
// return (otheremployee.kinid == this.kinid && otheremployee.location == this.location && otheremployee.empname == this.empname && otheremployee.managerKin == this.managerKin);
//}
public override bool Equals(object obj) //When Running this entire code, put a break-point on both the Equals() and GetHashCode() methods, and see the execution flow.
{
employee otheremployee;
otheremployee = (employee)obj;
return (obj.GetHashCode() == otheremployee.GetHashCode());
}
public override int GetHashCode() //When Running this entire code, put a break-point on both the Equals() and GetHashCode() methods, and see the execution flow.
{
//int temp = base.GetHashCode(); // DONT USE THIS
//return base.GetHashCode();
int temp = empname.GetHashCode() + location.GetHashCode() + kinid.GetHashCode() + managerKin.GetHashCode();
return temp;
}
}
public class manager
{
public string managername { get; set; }
public double kinid { get; set; }
public override int GetHashCode()
{
return base.GetHashCode();
}
public override bool Equals(object obj)
{
return base.Equals(obj);
}
}
public class program
{
public static void Main()
{
employee emp = new employee();
employee emp2 = new employee();
manager mng = new manager();
manager mng2 = new manager();
emp.empname = "Deepak";
emp.location = "Pune";
emp.kinid = 36885;
emp.managerKin = 007;
emp2.empname = "Astha";
emp2.location = "Pune";
emp2.kinid = 30000;
emp2.managerKin = 001;
mng.kinid = 007;
mng.managername = "Gaurav";
mng2.kinid = 001;
mng2.managername = "Surya";
Dictionary<employee, manager> relations = new Dictionary<employee, manager>();
relations.Add(emp, mng); // put a BreakPoint here and see the execution flow
relations.Add(emp2, mng2);// put a BreakPoint here and see the execution flow
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("The Employee details are :");
foreach (var element in relations)
Console.WriteLine(" \n Employee Name : {0} \n Location : {1} \n Employee KinId : {2} \n Manager's KinId : {3} ",
element.Key.empname, element.Key.location, element.Key.kinid, element.Key.managerKin);
Console.WriteLine("Enter the details of the Employee..");
Console.ForegroundColor = ConsoleColor.Gray;
Console.Write("\nEmployee Name : "); string ename = Console.ReadLine();
Console.Write("Location : "); string elocn = Console.ReadLine();
Console.Write("Employee KinId : "); double ekinid = Convert.ToDouble(Console.ReadLine());
Console.Write("Manager's ID : "); double emngr = Convert.ToDouble(Console.ReadLine());
employee emp1 = new employee();
emp1.empname = ename;
emp1.location = elocn;
emp1.kinid = ekinid;
emp1.managerKin = emngr;
int i = 0; // This variable acts as a indicator to find whether the Employee Key exists or not.
if (relations.ContainsKey(emp1)) //Put a break point here and see the execution flow.
{
Console.WriteLine("the Employee : {0} exists..", emp1.empname);
Console.WriteLine("the Employee reports to the following manager : {0} \n and the Manager's KinId is {1}.", (relations[emp1]).managername, relations[emp1].kinid);
i = 1;
Console.ReadLine();
}
if (i == 0)
{
Console.WriteLine("the details of the employee named {0} does not exist !!", emp1.empname);
Console.ReadLine();
}
#endregion
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