using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp1
{

    public class MyObject
    {
        private string id;
        private DateTime date;

        public MyObject(string _id, DateTime _date)
        {
            this.id = _id;
            this.date = _date;
        }
        public string Id
        {
            get { return id; }
            set { id = value; }
        }

        public DateTime Date
        {
            get { return date; }
            set { date = value; }
        }
    }
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            List<MyObject> MyObjectList = new List<MyObject>();

            MyObjectList.Add(new MyObject("1", new DateTime(2021, 8, 30)));
            MyObjectList.Add(new MyObject("2", new DateTime(2021, 8, 05)));
            MyObjectList.Add(new MyObject("3", new DateTime(2021, 8, 28)));
            MyObjectList.Add(new MyObject("4", new DateTime(2021, 8, 10)));

            //Methode 1
            MyObject MaxObj1 =  MyObjectList.FirstOrDefault(x => x.Date == MyObjectList.Max(y => y.Date).Date);
            MessageBox.Show(MaxObj1.Id);

            //Methode 2
            MyObject MaxObj2 = MyObjectList.First(); // just initiation
            for (var i = 0; i < MyObjectList.Count; i++)
            {
                for (var j = 0; j < MyObjectList.Count; j++)
                {
                    if(MyObjectList[j].Date > MyObjectList[i].Date)
                    {
                        MaxObj2 = MyObjectList[j];
                        break;
                    }
                }
            }
            MessageBox.Show(MaxObj2.Id);

            //Methode 3
            MyObject MaxObj3 = MyObjectList.First(); // just initiation
            foreach (MyObject obj in MyObjectList)
            {
                foreach (MyObject obj2 in MyObjectList)
                {
                    if(obj2.Date > obj.Date)
                    {
                        MaxObj3 = obj2;
                        break;
                    }
                }
            }
            MessageBox.Show(MaxObj3.Id);
        }
    }
}