C# Xamarin Android - 在 onCreate() 之外更改按钮属性答案

【问题标题】：C# Xamarin Android - Change button properties outside of onCreate()C# Xamarin Android - 在 onCreate() 之外更改按钮属性
【发布时间】：2018-12-14 15:45:32
【问题描述】：

我用一些按钮设置了一个活动。一个按钮用于启动蓝牙连接。所以活动开始了，在某些时候用户点击“开始蓝牙”，然后蓝牙连接建立，完成后我想启用另一个按钮以获得更多选项。

我的问题：如何在活动的 onCreate() 函数之外将按钮从 Enabled = False 更改为 Enabled = True？我的代码：在 onActivityResult() 方法中，我想启用按钮 buttonConnect。我的解决方案似乎不起作用。

我只能找到 onClickListeners，但这不是我需要的...

using Android.App;
using Android.OS;
using Android.Support.V7.App;
using Android.Runtime;
using Android.Widget;
using Android.Bluetooth;
using Android.Util;

using Android.Content;
using System.Reflection;

namespace firstTry3
{
    [Activity(Label = "@string/app_name")]
    public class bluetoothConnectionActivity : AppCompatActivity
{
    BluetoothAdapter mBluetoothAdapter;
    const int REQUEST_ENABLE_BT = 1;        //necessary to start bluetooth, must be greater than 0
    string tag = "blueApp";


    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.activity_bluetoothConnection);

        Button buttonBluetoothOn = FindViewById<Button>(Resource.Id.bluetoothOn);
        Button buttonConnect = FindViewById<Button>(Resource.Id.connectButton);
        Button buttonDissconnect = FindViewById<Button>(Resource.Id.disconnectButton);

        mBluetoothAdapter = BluetoothAdapter.DefaultAdapter;

        buttonBluetoothOn.Click += (sender, e) =>
        {
            if (!mBluetoothAdapter.IsEnabled)
            {
                Log.Info(tag, MethodBase.GetCurrentMethod().Name + ": Device does not have bluetooth capabilities");
            }
            enableBluetooth();
        };
    }

    public void enableBluetooth() {
        if(mBluetoothAdapter == null)
        {
            Log.Warn(tag, MethodBase.GetCurrentMethod().Name + ": Device does not have bluetooth capabilities");
        }
        if (!mBluetoothAdapter.IsEnabled)
        {
            Intent enableBTIntent = new Intent(BluetoothAdapter.ActionRequestEnable);
            StartActivityForResult(enableBTIntent, REQUEST_ENABLE_BT);
        }
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if (resultCode == constants.RESULT_OK)
        {
            Log.Info(tag, MethodBase.GetCurrentMethod().Name + ": Bluetooth has been activated");
            Button buttonConnect = FindViewById<Button>(Resource.Id.connectButton);
            buttonConnect.Enabled = true;

        }
        if (resultCode == constants.RESULT_CANCELLED){
            Log.Info(tag, MethodBase.GetCurrentMethod().Name + ": Bluetooth has NOT been activated");
        }
        else
        {
            Log.Error(tag, MethodBase.GetCurrentMethod().Name + ": invalid resultCode");
        }
    }
}

}

【问题讨论】：

标签： c# xamarin button xamarin.android oncreate

【解决方案1】：

在activity 级别声明您的button 并在OnCreate 中初始化它，然后您可以在当前activity 的任何地方使用它。像这样

public class bluetoothConnectionActivity : AppCompatActivity
{
    Button buttonConnect;
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.activity_bluetoothConnection);
        buttonConnect = FindViewById<Button>(Resource.Id.connectButton);
    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        if (resultCode == constants.RESULT_OK)
        {
            Log.Info(tag, MethodBase.GetCurrentMethod().Name + ": Bluetooth has been activated");
            buttonConnect.Enabled = true;
        }
    }
}

【讨论】：