代码之家 › 专栏 › 技术社区 › Soham Dasgupta

要列出的IEnumerable集合

.net c#

Soham Dasgupta · 技术社区 · 14 年前

我编写了一个CustomerCollection类,它实现了IEnumerable和IEnumerator接口。现在,我希望customerCollection类对象可以通过where()和find()函数进行搜索,还希望从customerCollection类中获取customer类型的列表对象。请帮忙。另外,接口的实现是否正确。

public class Customer
{
    private int _CustomerID;
    private string _CustomerName;

    public Customer(int customerID)
    {
        this._CustomerID = customerID;
    }

    public int CustomerID
    {
        get
        {
            return _CustomerID;
        }
        set
        {
            _CustomerID = value;
        }
    }

    public string CustomerName
    {
        get
        {
            return _CustomerName;
        }
        set
        {
            _CustomerName = value;
        }
    }
}

public class CustomerController
{
    public ArrayList PopulateCustomer()
    {
        ArrayList Temp = new ArrayList();

        Customer _Customer1 = new Customer(1);
        Customer _Customer2 = new Customer(2);

        _Customer1.CustomerName = "Soham Dasgupta";
        _Customer2.CustomerName = "Bappa Sarkar";

        Temp.Add(_Customer1);
        Temp.Add(_Customer2);

        return Temp;
    }
}

public class CustomerCollection : IEnumerable, IEnumerator
{
    ArrayList Customers = null;
    IEnumerator CustomerEnum = null;

    public CustomerCollection()
    {
        this.Customers = new CustomerController().PopulateCustomer();
        this.CustomerEnum = Customers.GetEnumerator();
    }

    public void SortByName()
    {
        this.Reset();
    }

    public void SortByID()
    {
        this.Reset();
    }

    public IEnumerator GetEnumerator()
    {
        return (IEnumerator)this;
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return (IEnumerator)this;
    }

    public void Reset()
    {
        CustomerEnum.Reset();
    }

    public bool MoveNext()
    {
        return CustomerEnum.MoveNext();
    }

    public object Current
    {
        get
        {
            return (Customer)CustomerEnum.Current;
        }
    }

}

6 回复 | 直到 14 年前

Daniel Dyson 14 年前

这会满足你的需要。注意,我抽象了IEnumerable,使其可重用,并降低了所有其他类的复杂性。

//Write your Test first
public class Test
{
    public void TestEnumerator()
    {
        var customers = new CustomerCollection();
        var qry = 
            from c in customers
            select c;

        foreach (var c in qry)
        {
            Console.WriteLine(c.CustomerName);
        }

        //Create a new list from the collection:
        var customerList = new List<Customer>(customers);
    }
}

public abstract class MyColl<T> : IEnumerable<T>
{
    protected T[] Items;
    public IEnumerator<T> GetEnumerator()
    {
        foreach (T item in Items)
        {
            yield return item;
        }
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }
}

public class Customer
{
    public Customer(int customerID)
    {
        CustomerID = customerID;
    }
    public int CustomerID { get; set; }
    public string CustomerName { get; set; }
}

public class CustomerController
{
    public Customer[] PopulateCustomer() {
       return new [] {new Customer(1) {CustomerName = "Soham Dasgupta"},
                      new Customer(2) {CustomerName = "Bappa Sarkar"}};
    }
}

public class CustomerCollection : MyColl<Customer>
{

    public CustomerCollection()
    {
        Items = new CustomerController().PopulateCustomer();
    }
}

Matt Greer 14 年前

你可以打电话 Cast<Customer>() 在你的IEnumerable上,它会给你一个 IEnumerable<Customer> 或者只是执行 IEnumerable<客户> 首先。Linq几乎完全被 IEnumerable<T> 不是 IEnumerable . 一旦你做到了这一点,你就可以免费得到所有的物品。

abatishchev Karl Johan 14 年前

我建议使用 OfType<T>() 而不是 Cast<T>() 因为如果你的收藏包含T1和T2, collection.Cast<T1>() 将引发错误 collection.OfType<T1>() 将返回 IEnumerable<T1> 仅包含T1而不是T2的实例

chugh97 14 年前

public class CustomerController 
{ 
    public List<Customer> PopulateCustomer() 
    { 
        List<Customer> Temp = new ArrayList(); 

        Customer _Customer1 = new Customer(1); 
        Customer _Customer2 = new Customer(2); 

        _Customer1.CustomerName = "Soham Dasgupta"; 
        _Customer2.CustomerName = "Bappa Sarkar"; 

        Temp.Add(_Customer1); 
        Temp.Add(_Customer2); 

        return Temp; 
    } 
} 


public class CustomerCollection : List<Customer>
{  
    List<Customer> Customers = new List<Customer>();  


    public CustomerCollection()  
    {  
        this.Customers = new CustomerController().PopulateCustomer();  
    }    

}

manixrock 14 年前

new List<Customer>(myCustomerEnumerator);

Cameron MacFarland 14 年前

建议用于创建自己的集合实现的基类是 System.Collections.ObjectModel.Collection<T>

(来自MSDN)
提供这个基类是为了使实现人员更容易创建自定义集合。鼓励实现者扩展这个基类,而不是创建自己的基类。

public class CustomerCollection : Collection<Customer>
{
}