来自AlertDialog的c# Xamarin安卓返回响应bool
来自AlertDialog的c# Xamarin安卓返回响应bool
提问于 2018-06-19 20:50:47
如果用户从AlertDialog中选择yes，我会尝试返回一个布尔值true，反之亦然。
目前，它总是返回false。看起来布尔值“结果”永远不会被设定。
public bool AskForConfirmation(string messege, Context context)
{
bool result;
Android.Support.V7.App.AlertDialog.Builder dialog = new Android.Support.V7.App.AlertDialog.Builder(context);
dialog.SetPositiveButton("Yes", (sender, args) =>
{
result = true;
});
dialog.SetNegativeButton("No", (sender, args) =>
{
result = false;
}).SetMessage(messege).SetTitle("System Message");
dialog.Show();
return result;
}然后我调用这个方法
this.RunOnUiThread(() =>
{
bool response = ioManager.AskForConfirmation("Message", this);
Console.WriteLine("Response is " + response);
});回答 1
Stack Overflow用户
回答已采纳
发布于 2018-06-20 05:37:15
您可以通过ManualResetEvent或TaskCompletionSource创建一个Task-based对话框，因此您可以这样调用它：
通过TaskCompletionSource使用示例：
try
{
var result = await DialogAsync.Show(this, "StackOverflow", "Does it rock?");
Log.Debug("SO", $"Dialog result: {result}");
}
catch (TaskCanceledException ex)
{
Log.Debug("SO", $"Dialog cancelled; backbutton, click outside dialog, system-initiated, .... ");
}通过TaskCompletionSource的DialogAsync示例：
public class DialogAsync : Java.Lang.Object, IDialogInterfaceOnClickListener, IDialogInterfaceOnCancelListener
{
readonly TaskCompletionSource<bool?> taskCompletionSource = new TaskCompletionSource<bool?>();
public DialogAsync(IntPtr handle, Android.Runtime.JniHandleOwnership transfer) : base(handle, transfer) { }
public DialogAsync() { }
public void OnClick(IDialogInterface dialog, int which)
{
switch (which)
{
case -1:
SetResult(true);
break;
default:
SetResult(false);
break;
}
}
public void OnCancel(IDialogInterface dialog)
{
taskCompletionSource.SetCanceled();
}
void SetResult(bool? selection)
{
taskCompletionSource.SetResult(selection);
}
public async static Task<bool?> Show(Activity context, string title, string message)
{
using (var listener = new DialogAsync())
using (var dialog = new AlertDialog.Builder(context)
.SetPositiveButton("Yes", listener)
.SetNegativeButton("No", listener)
.SetOnCancelListener(listener)
.SetTitle(title)
.SetMessage(message))
{
dialog.Show();
return await listener.taskCompletionSource.Task;
}
}
}通过ManualResetEvent使用示例：
using (var cancellationTokenSource = new CancellationTokenSource())
{
var result = await DialogAsync.Show(this, "StackOverflow", "Does it rock?", cancellationTokenSource);
if (!cancellationTokenSource.Token.IsCancellationRequested)
{
Log.Debug("SO", $"Dialog result: {result}");
}
else
{
Log.Debug("SO", $"Dialog cancelled; backbutton, click outside dialog, system-initiated, .... ");
}
}通过ManualResetEvent的DialogAsync示例：
public class DialogAsync : Java.Lang.Object, IDialogInterfaceOnClickListener, IDialogInterfaceOnCancelListener
{
readonly ManualResetEvent resetEvent = new ManualResetEvent(false);
CancellationTokenSource cancellationTokenSource;
bool? result;
public DialogAsync(IntPtr handle, Android.Runtime.JniHandleOwnership transfer) : base(handle, transfer) { }
public DialogAsync() { }
public void OnClick(IDialogInterface dialog, int which)
{
switch (which)
{
case -1:
SetResult(true);
break;
default:
SetResult(false);
break;
}
}
public void OnCancel(IDialogInterface dialog)
{
cancellationTokenSource.Cancel();
SetResult(null);
}
void SetResult(bool? selection)
{
result = selection;
resetEvent.Set();
}
public async static Task<bool?> Show(Activity context, string title, string message, CancellationTokenSource source)
{
using (var listener = new DialogAsync())
using (var dialog = new AlertDialog.Builder(context)
.SetPositiveButton("Yes", listener)
.SetNegativeButton("No", listener)
.SetOnCancelListener(listener)
.SetTitle(title)
.SetMessage(message))
{
listener.cancellationTokenSource = source;
context.RunOnUiThread(() => { dialog.Show(); });
await Task.Run(() => { listener.resetEvent.WaitOne(); }, source.Token);
return listener.result;
}
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50928924
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