Xamarin C＃ - Android的 - 防止AlertDialog關閉PositiveButton點擊

Question

我是Xamarin新手，我不知道如何在c＃中執行以下操作。點擊Positive/Negative按鈕時，我想阻止alertdialog關閉。我需要首先對輸入進行驗證。如果輸入正確，對話框可以關閉，否則我將顯示帶有指示的消息。基本上，我有以下代碼：

private void CreateAddProjectDialog() { 
    //some code 
    var alert = new AlertDialog.Builder (this); 
    alert.SetTitle ("Create new project"); 
    alert.SetView (layoutProperties); 
    alert.SetCancelable (false); 
    alert.SetPositiveButton("Create", HandlePositiveButtonClick); 
    alert.SetNegativeButton("Cancel", HandelNegativeButtonClick); 
} 

private void HandlePositiveButtonClick (object sender, EventArgs e) { 
    //Do some validation here and return false (prevent closing of dialog) if invalid, else close.... 
} 

現在，我紅StackOverflow上以下職位：How to prevent a dialog from closing when a button is clicked

我認爲下面的代碼（從線程所）有解決方案，但我不知道如何重寫我的C＃代碼來實現Java：

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); 
builder.setMessage("Test for preventing dialog close"); 
builder.setPositiveButton("Test", 
    new DialogInterface.OnClickListener() 
    { 
     @Override 
     public void onClick(DialogInterface dialog, int which) 
     { 
      //Do nothing here because we override this button later to change the close behaviour. 
      //However, we still need this because on older versions of Android unless we 
      //pass a handler the button doesn't get instantiated 
     } 
    }); 
AlertDialog dialog = builder.create(); 
dialog.show(); 
//Overriding the handler immediately after show is probably a better approach than  OnShowListener as described below 
dialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() 
{ 

    @Override 
    public void onClick(View v) 
    { 
     Boolean wantToCloseDialog = false; 
     //Do stuff, possibly set wantToCloseDialog to true then... 
     if(wantToCloseDialog) 
       dismiss(); 
     //else dialog stays open. Make sure you have an obvious way to close the dialog especially if you set cancellable to false. 
    } 
}); 

如何在c＃中編碼？特別是setPositiveButton區域中的覆蓋部分...

Answer 1

這需要在盒子外面思考一下。你將不得不直接處理AlertDialog對象：

// Build the dialog. 
var builder = new AlertDialog.Builder(this); 
builder.SetTitle("Click me!"); 

// Create empty event handlers, we will override them manually instead of letting the builder handling the clicks. 
builder.SetPositiveButton("Yes", (EventHandler<DialogClickEventArgs>)null); 
builder.SetNegativeButton("No", (EventHandler<DialogClickEventArgs>)null); 
var dialog = builder.Create(); 

// Show the dialog. This is important to do before accessing the buttons. 
dialog.Show(); 

// Get the buttons. 
var yesBtn = dialog.GetButton((int)DialogButtonType.Positive); 
var noBtn = dialog.GetButton((int)DialogButtonType.Negative); 

// Assign our handlers. 
yesBtn.Click += (sender, args) => 
{ 
    // Don't dismiss dialog. 
    Console.WriteLine("I am here to stay!"); 
}; 
noBtn.Click += (sender, args) => 
{ 
    // Dismiss dialog. 
    Console.WriteLine("I will dismiss now!"); 
    dialog.Dismiss(); 
};