构建工作正常，但媒体播放似乎未加载

Question

i'm working on an android app at the moment that has the purpose of playing a particular song at exactly midnight. I know that there might already be apps in the appstore that serve that purpose, but I'm new to coding and wanted to try to program the app myself. So now I reached the point where I don't know what to do anymore. I tried debugging the App on my LG H818P running Android 6.0. It posted, The Icon, the Name and everything were correct, but i didn't play the song, even when i set the time when it should've played it to two minutes after the start if the building.

So that's the code of the MainActivity.cs in Visual Studio 2017, can anyone find any errors?

using Android.App;
using Android.Widget;
using Android.OS;
using System;
using Android.Media;

namespace Name of the App
{
    [Activity(Label = "Name of the App", MainLauncher = true)]
    public class MainActivity : Activity


    {
        string text = "status";
        protected void onCreate(Bundle savedInstanceState)

        {


        }

        public void main()
        {
            try
            {

                string systemtime = DateTime.Now.ToString();

                for (int i = 0; i > 0; i++)
                {
                    if (systemtime == "09:07:00 pm")
                    {
                        StartPlayer();
                        player.Start();
                    }
                }
            }
            catch
            {
                text = "Error!";
            }
        }

        protected MediaPlayer player;
        public void StartPlayer()
        {
            if (player == null)
            {
                player = new MediaPlayer();
                player.SetDataSource("Ressources.raw.file2beplayed.mp3");
                player.Prepare();
                player.Start();
                text = "Playing!";
            }
            else
            {
                player.Reset();
                player.SetDataSource("Ressources.raw.file2beplayed.mp3");
                player.Prepare();
                player.Start();
            }
        }

    }


}

As I said, I'm a Noob in coding, so sorry for the maybe ugly code :) Thanks for your replies!

Answer 1

The default format for ToString in a DateTime is MM/dd/yyyy , so your comparation systemtime == "09:07:00 pm" will never be true.

You can use a TimeSpan and the property TimeOfDay from DateTime ;

if(DateTime.Now.TimeOfDay == new Timespan(21,7,0))
  //...

Also, your loop will never be executed as you initialize i as 0, so at the first check i will not be greater than 0 so the loop isn't executed.

Finally, Android does not use the main function, is an special type of program, your initialization code should be in the OnCreate function, but if you create an infinite loop in that function Android will close the application as it will not finish it's initialization, you need to use a timer and check the condition each second.