monodroid Timer

问题:

I want to use a timer in my C# monodroid program for android 2.2, but it doesnt work. here is my code:

using System;
using System.Timers;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using Android.Util;

namespace MonoAndroidApplication1
{
[Activity(Label = "MonoAndroidApplication1", MainLauncher = true, Icon=drawable/icon")]
public class Activity1 : Activity
{
    int count = 1;
    TextView txv1;
    System.Timers.Timer t1;
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);
        txv1 = FindViewById<TextView>(Resource.Id.txv1);
        DateTime dt = DateTime.Now;
        txv1.Text = dt.ToShortTimeString();
        t1 = new System.Timers.Timer(200);
        t1.Elapsed += new ElapsedEventHandler(OnTimeEvent);
        t1.Interval = 200;
        t1.Enabled = true;
        t1.Start();


    }
    private void OnTimeEvent(object source, ElapsedEventArgs e)
    {
        txv1.Text = count.ToString();
        count++;
    }
}
}

please help me.

回答1:

System.Timers.Timer will be running on a separate (non-UI) thread. Consequently, your OnTimeEvent() method is incorrect, as it will be updating a UI instance (txv1) from a non-UI thread.

You need to use Activity.RunOnUiThread() to update the UI from a background thread:

private void OnTimeEvent(object source, ElapsedEventArgs e)
{
    RunOnUiThread(delegate {
        txv1.Text = count.ToString ();
        count++;
    });
}