如何返回

Question

我創建了一個custimazibale提示，只有當「OK」點擊值

public static class Prompt 
{ 
    public static string ShowDialog(int columnnumber, string columnname) 
    { 
     Form prompt = new Form(); 
     prompt.Width = 500; 
     prompt.Height = 150; 
     prompt.FormBorderStyle = FormBorderStyle.FixedDialog; 
     prompt.Text = columnname; 
     prompt.StartPosition = FormStartPosition.CenterScreen; 
     Label textLabel = new Label() { Left = 50, Top = 20 }; 
     ComboBox comboBox = new ComboBox() { Left = 50, Top = 50, Width = 400 }; 
     comboBox.Items.AddRange(new string[] { "a","b","c" }); 
     comboBox.DropDownStyle = ComboBoxStyle.DropDownList; 
     comboBox.SelectedItem = columnname; 
     Button confirmation = new Button() { Text = "Ok", Left = 350, Width = 100, Top = 80 }; 
     confirmation.Click += (sender, e) => { prompt.Close(); }; 
     textLabel.Text = "Colonne " + (columnnumber + 1).ToString() + " : " + columnname; 
     prompt.Controls.Add(comboBox); 
     prompt.Controls.Add(confirmation); 
     prompt.Controls.Add(textLabel); 
     prompt.AcceptButton = confirmation; 
     prompt.ShowDialog(); 
     prompt.AcceptButton = confirmation; 

     return comboBox.Text; 
    } 
} 

然後我把它在我的主要形式被點擊

private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) 
{ 
    dt.Columns[e.ColumnIndex].ColumnName = Prompt.ShowDialog(e.ColumnIndex, dataGridView1.Columns[e.ColumnIndex].Name); 
} 

問題的標題時，即使點擊按鈕關閉，我的文字也會變化。 但我希望它只在用戶點擊「確定」按鈕時才能更改。

Answer 1

您可以設定當確認一個布爾值，並用它來返回null如果沒有被證實，像這樣：

public static string ShowDialog(int columnnumber, string columnname) 
{ 
    Form prompt = new Form(); 
    prompt.Width = 500; 
    prompt.Height = 150; 
    prompt.FormBorderStyle = FormBorderStyle.FixedDialog; 
    prompt.Text = columnname; 
    prompt.StartPosition = FormStartPosition.CenterScreen; 
    Label textLabel = new Label() 
    { 
     Left = 50, 
     Top = 20 
    }; 
    ComboBox comboBox = new ComboBox() 
    { 
     Left = 50, 
     Top = 50, 
     Width = 400 
    }; 
    comboBox.Items.AddRange(new string[] { "a", "b", "c" }); 
    comboBox.DropDownStyle = ComboBoxStyle.DropDownList; 
    comboBox.SelectedItem = columnname; 
    Button confirmation = new Button() 
    { 
     Text = "Ok", 
     Left = 350, 
     Width = 100, 
     Top = 80 
    }; 

    bool confirmed = false; 

    confirmation.Click += (sender, e) => 
    { 
     prompt.Close(); 
     confirmed = true; 
    }; 
    textLabel.Text = "Colonne " + (columnnumber + 1).ToString() + " : " + columnname; 
    prompt.Controls.Add(comboBox); 
    prompt.Controls.Add(confirmation); 
    prompt.Controls.Add(textLabel); 
    prompt.AcceptButton = confirmation; 
    prompt.ShowDialog(); 
    prompt.AcceptButton = confirmation; 

    return confirmed ? comboBox.Text : null; 
} 

調用代碼將需要檢查返回值零，只有在返回的值不爲空時纔會執行某些操作。

Answer 2

你可以評估DialogResult，並返回null如果不是OK：

public static class Prompt 
{ 
    public static string ShowDialog(int columnnumber, string columnname) 
    { 
     using (Form prompt = new Form()) 
     { 
      // other code 
      return prompt.DialogResult == DialogResult.OK ? comboBox.Text : null; 
     } 
    } 
} 

，然後在你的另一種方法：

private void dataGridView1_ColumnHeaderMouseClick(object sender, EventArgs e) 
{ 
    var result = Prompt.ShowDialog(e.ColumnIndex, 
            dataGridView1.Columns[e.ColumnIndex].Name); 
    if (result != null) 
     dt.Columns[e.ColumnIndex].ColumnName = result; 
} 

而且你裏面prompt你應該相應地設置DialogResult：

confirmation.Click += (sender, e) => 
    { 
     prompt.DialogResult = DialogResult.OK; 
     prompt.Close(); 
    }; 

建議：而不是result != null也可以使用!String.IsNullOrWhiteSpace(result)更新列名稱，如果輸入了內容。

Answer 3

我會去這樣的事情：

using(Form prompt = new Form()) 
{ 
    //Initialize the components of your form 

    DialogResult result = prompt.ShowDialog(); 
    if(result == DialogResult.OK) 
    { 
     //return whatever it is you want to return 
    } 
} 

內，您的表格，您可以通過prompt.DialogResult = DialogResult.OK設置的DialogResult和一些更多的選擇（DialogResult.Cancel，DialogResult.Retry等）