Windows Service to Check if any folder is containing any files

using Microsoft.SharePoint;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.ServiceProcess;
using System.Text;
using System.Threading.Tasks;

namespace HelloworldService
{
    public partial class Service1 : ServiceBase
    {
        System.Timers.Timer timer =  new System.Timers.Timer();
        public Service1()
        {
            InitializeComponent();
        }

        protected override void OnStart(string[] args)
        {
            System.IO.StreamWriter file = new System.IO.StreamWriter("C:\\abhas.txt", true);
            file.WriteLine(DateTime.Now + "Service Has Started");
         
            timer.Interval = 60000; // 60 seconds
            timer.Enabled = true;

            timer.Elapsed += new System.Timers.ElapsedEventHandler(this.OnTimer);
            timer.Start();

         
            String fileName = string.Empty; String filePath;
         
            filePath = System.Configuration.ConfigurationManager.AppSettings["Folderpath"].ToString();
            string[] filePaths = Directory.GetFiles(filePath);



            DirectoryInfo di = new DirectoryInfo("C:\\Dropbox");
            FileInfo[] fi = di.GetFiles("*", SearchOption.AllDirectories);
            if (Convert.ToInt32(fi.Length)>0)
            {
                file.WriteLine(DateTime.Now + "There ares ome files");
            }
            else
            {
                file.WriteLine(DateTime.Now + "No Files Present");
            }
         
            file.Close();
         

        }

        private void OnTimer(object sender, System.Timers.ElapsedEventArgs e)
        {
            System.IO.StreamWriter file = new System.IO.StreamWriter("C:\\abhas.txt", true);
            String fileName = string.Empty; String filePath;
         
            filePath = System.Configuration.ConfigurationManager.AppSettings["Folderpath"].ToString();
            string[] filePaths = Directory.GetFiles(filePath);



            DirectoryInfo di = new DirectoryInfo("C:\\Dropbox");
            FileInfo[] fi = di.GetFiles("*", SearchOption.AllDirectories);
            if (Convert.ToInt32(fi.Length) > 0)
            {
                file.WriteLine(DateTime.Now + "There ares Some files");
            }
            else
            {
                file.WriteLine(DateTime.Now + "No Files Present");
            }
            file.Close();
        }

     

        protected override void OnStop()
        {
        }
    }
}