在 Xamarin.Android 的广播接收器中使用 FindViewById 时出错

Question

我有一个 activity，里面有一个 BroadcastReceiver，如下代码所示：

public  class MyActivity : Activity
    {
       protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        // Create your application here
        SetContentView(Resource.Layout.activity_myActivity);

        int method = Intent.GetIntExtra(KEY_MYACTIVITY_METHOD, METHOD_MYACTIVITY);

        mAlgo= new algo(this);            
        intent = new Intent(this, typeof( BroadcastService) ); //*****
    }

     [BroadcastReceiver(Enabled = true)]
    [IntentFilter(new[] { Android.Content.Intent.ActionBootCompleted })]
    private  class broadcastReceiver : BroadcastReceiver
    {
        public override void OnReceive(Context context, Intent intent)
        {
            updateUI(intent);
        }
        private   void updateUI(Intent intent)
        {
            float mx = mAlgo.getmX();

            TextView startx =FindViewById<TextView>(Resource.Id.startx);  //ERROR


        }

    }
}

我遇到 FindViewById 错误，它告诉我属性、方法或非静态字段 Activity.FindViewById(int)' 需要对象引用。你能看出哪里出了问题吗？谢谢

Answer 1

您不能从嵌套的 class 调用 FindViewById。你可以：

1) 在嵌套的 broadcastReceiver class:

中持有对 activity 对象的引用

public class MyActivity : Activity {

    ...

    private class broadCastReceiver : BroadcastReceiver {
        private MyActivity act;

        public broadCastReceiver (MyActivity act) {
            this.act = act;
        }

        private void updateUI (Intent intent) {
            TextView startx = act.FindViewById<TextView> (Resource.Id.startx);
        }
    }
}

2) 或者在 activity 中保存对 TextView 的引用，并像第一个示例一样将其传递给广播接收器。

在 Xamarin.Android 的广播接收器中使用 FindViewById 时出错

Error with FindViewById used in a Broadcast receiver with Xamarin.Android

c#

xamarin.android

findviewbyid