Practical usage of Find<T> Method in Generic List<T> using Predicate

Step 1: Used Namespaces:

using System;
using System.Collections.Generic;

Step 2: Used Collection for demo:

// <summary>
/// This is static collection used in this tutorials
/// </summary>
/// <returns></returns>
private List<CompanyProduct> AddCollection()
{
    list.Add(new CompanyProduct("MS Word", 1, "Microsoft", new DateTime(2012, 10, 31)));
    list.Add(new CompanyProduct("MS Excel", 2, "Microsoft", new DateTime(2011, 10, 31)));
    list.Add(new CompanyProduct("MS Powerpoint", 3, "Microsoft", new DateTime(2010, 10, 31)));
    list.Add(new CompanyProduct("Visual Studio", 2, "Microsoft", new DateTime(2011, 10, 31)));
    list.Add(new CompanyProduct("Sql Server", 3, "Microsoft", new DateTime(2010, 10, 31)));
    list.Add(new CompanyProduct("Oracle", 4, "Oracle", new DateTime(2011, 10, 31)));
    list.Add(new CompanyProduct("Sharepoint", 6, "Microsoft", new DateTime(2012, 10, 31)));
    list.Add(new CompanyProduct("MS Outlook", 7, "Microsoft", new DateTime(2011, 10, 31)));
    return list;
}

Step 3: Printing the collection:

    List<CompanyProduct> list = AddCollection();
    PrintList(list, "Available Collection");

Filtering the first product by company name using Predicate
 
    //Filter the first product by company name.
    CompanyProduct cp = list.Find(delegate(CompanyProduct item) { return item.CompanyName == "Microsoft"; });
    Response.Write("<br/>");
    Response.Write(string.Format("  Product={0} >>> CompanyName={1}",
    cp.Product, cp.CompanyName));

Step 4: Filtering the first product by product id using Predicate

    //Filter the first product by product id.
    cp = list.Find(delegate(CompanyProduct item) { return item.ProductID == 1; });
    Response.Write("<br/>");
    Response.Write(string.Format("  Product={0} >>> CompanyName={1}",
    cp.Product, cp.CompanyName));

Step 5: Filtering the first product by productRegisterDate using Predicate

    //Filter the first product by productRegisterDate.
    cp = list.Find(delegate(CompanyProduct item) { return item.ProductRegisterDate == new DateTime(2010, 10, 31); });
    Response.Write("<br/>");
    Response.Write(string.Format("  Product={0} >>> CompanyName={1}",
    cp.Product, cp.CompanyName));

Step 6: Used for printing the results:

    /// <summary>
    /// This is used to display the list after editing list.
    /// </summary>
    private void PrintList(List<CompanyProduct> list, string header)
    {
        Response.Write("<br/>");
        Response.Write(" " + header);
        Response.Write("<br/>");
 
        foreach (CompanyProduct cp in list)
        {
            //Response.Write(string.Format("Product={0} >>> ProductId={1} >>> CompanyName={2} >>> RegisterDate={3}",
            //   cp.Product, cp.ProductID, cp.CompanyName, cp.ProductRegisterDate));
 
            Response.Write(string.Format("  Product={0} >>> CompanyName={1}",
            cp.Product, cp.CompanyName));
 
            Response.Write("<br/>");
        }
 
        Response.Write("<br/>");
    }
}

Step 7: Used Class for Demo

class CompanyProduct
{
 
    public CompanyProduct(string product, int productID, string companyName, DateTime productRegisterDate)
    {
        this.product = product;
        this.productID = productID;
        this.companyName = companyName;
        this.productRegisterDate = productRegisterDate;
    }
 
    private string product;
    public string Product
    {
        get { return this.product; }
        set { this.product = value; }
    }
 
    private int productID;
    public int ProductID
    {
        get { return this.productID; }
        set { this.productID = value; }
    } 

    private string companyName;
    public string CompanyName
    {
        get { return this.companyName; }
        set { this.companyName = value; }
    }
 
    private DateTime productRegisterDate;
    public DateTime ProductRegisterDate
    {
        get { return this.productRegisterDate; }
        set { this.productRegisterDate = value; }
    }
}

Thanks for reading this blog. Have a nice day.