根据选择返回枚举值

Question

我有一个枚举

public enum Operation
{
    Add = 1,
    Substract = 2,
    Multiply = 3,
    Divide = 4
}

我有四个单选按钮：加、减、乘、除。

根据选择，我想返回对应的 Enum 值。我所有的单选按钮都出现在一个组合框中。

我知道这是一件简单的事情，但很长一段时间我都无法做到。谢谢。

编辑

这就是我尝试过的......

    public Operation Operation
    {
        get
        {
            foreach (Control control in gbxOperation.Controls)
            {
                var radioButton = control as radioButton;
                if (radioButton != null && radioButton.Checked)
                {
                    if(radioButton.Text.ToLower() == "add")
                        return Operation.Add;
                    if (radioButton.Text.ToLower() == "subtract")
                        return Operation.Substract;
                    if (radioButton.Text.ToLower() == "multiply")
                        return Operation.Multiply;
                    if (radioButton.Text.ToLower() == "divide")
                        return Operation.Divide;
                }
            }
            return Operation.Add;
        }
    }

Answer 1

你的问题不是很清楚，但是如果你有一个像"Add"这样的字符串，并且你想将它转换为Operation，你可以使用Enum.Parse()。比如：

Operation op = (Operation)Enum.Parse(typeof(Operation), s);

但可能更好的选择是将单选按钮与枚举值直接关联，而不是通过按钮的文本。具体如何操作取决于您使用的是哪种 UI 库。

Answer 2

您可以为此目的使用 RadioButton 的 Tag 属性：

在InitializeComponent()之后的构造函数中：

addButton.Tag = Operation.Add;
subtractButton.Tag = Operation.Subtract;
addButton.Tag = Operation.Multiply;
addButton.Tag = Operation.Divide;

public Operation Operation         
{             
  get             
  {
    RadioButton checkedButton = gbxOperation.Controls.OfType<RadioButton>().
                                             Where(button => button.Checked).First();
    return (Operation)(checkedButton.Tag);
  }
}   

Answer 3

我会选择将字符串 .Tag 添加到 RadioButton 控件与 Enum 中的名称的简单组合，并在按钮更改时解析事件中的字符串：

public Operation Operation { get; private set; }

private void rb_CheckedChanged(object sender, EventArgs e)
{
    var rb = sender as RadioButton;
    if (rb.Checked)
    {
        this.Operation = (Operation)Enum.Parse(typeof(Operation), rb.Tag as string);
        ...
    }
}

Answer 4

我假设您使用的是 Windows 窗体。在下面的示例中，您可以使用多种方法中的两种：

1. 使用用于自定义用户数据的 Tag 属性。然后，您可以将 Tag 值转换为已选中的单选按钮的枚举。

2. 或者，只需在单选按钮和枚举之间创建一个字典。您可以使用单选按钮作为键，使用操作枚举作为您的值。

问候。

public class MyForm : Form
{
    public MyForm()
    {
        InitializeComponent();


        // Method 1) The Tag property on any control can be user as user data
        radioButton1.Tag = Operation.Add;
        radioButton2.Tag = Operation.Subtract;
        radioButton3.Tag = Operation.Multiply;
        radioButton4.Tag = Operation.Divide;

        // Method 2) Use a Dictionary
        radioButtonToOperation = new Dictionary<RadioButton, Operation> 
            {
                { radioButton1, Operation.Add },
                { radioButton2, Operation.Subtract },
                { radioButton3, Operation.Multiply },
                { radioButton4, Operation.Divide },
            };
    }

    // Fields
    GroupBox groupBox1;
    RadioButton radioButton1;
    RadioButton radioButton2;
    RadioButton radioButton3;
    RadioButton radioButton4;
    Dictionary<RadioButton, Operation> radioButtonToOperation;

    private void InitializeComponent()
    {   
        groupBox1 = new GroupBox();
        radioButton1 = new RadioButton();
        radioButton2 = new RadioButton();
        radioButton3 = new RadioButton();
        radioButton4 = new RadioButton();

        groupBox1.Text = "Operations";
        groupBox1.Dock = DockStyle.Fill;

        radioButton1.Text = "Add";
        radioButton1.Dock = DockStyle.Top;
        radioButton1.CheckedChanged += radioButtons_CheckedChanged;

        radioButton2.Text = "Subtract";
        radioButton2.Dock = DockStyle.Top;
        radioButton2.CheckedChanged += radioButtons_CheckedChanged;

        radioButton3.Text = "Multiply";
        radioButton3.Dock = DockStyle.Top;
        radioButton3.CheckedChanged += radioButtons_CheckedChanged;

        radioButton4.Text = "Divide";
        radioButton4.Dock = DockStyle.Top;
        radioButton4.CheckedChanged += radioButtons_CheckedChanged;

        groupBox1.Controls.Add(radioButton4);
        groupBox1.Controls.Add(radioButton3);
        groupBox1.Controls.Add(radioButton2);
        groupBox1.Controls.Add(radioButton1);
        Controls.Add(groupBox1);
    }

    void radioButtons_CheckedChanged(object sender, EventArgs e)
    {
        RadioButton radioButton = sender as RadioButton;
        if (radioButton == null) return;  // Not a radio button
        if (!radioButton.Checked) return; // Radio button isn't checked

        // Method 1) Get the Operation from the Tag property
        Operation? operationFromTag = GetOperationFromTag(radioButton);
        Console.WriteLine("From Tag: " + (operationFromTag == null ? "(none)" : operationFromTag.ToString() ));

        // OR Method 2) Get the Operation from the Dictionary
        Operation? operationFromDictionary = GetOperationUsingDictionary(radioButton);
        Console.WriteLine("From Dictionary: " + (operationFromDictionary == null ? "(none)" : operationFromDictionary.ToString()) );
    }

    private Operation? GetOperationFromTag(RadioButton radioButton)
    {
        if (radioButton == null) return null;

        if (radioButton.Tag is Operation)
        {
            Operation operationFromTag = (Operation)radioButton.Tag;
            return operationFromTag;
        }

        return null;
    }


    private Operation? GetOperationUsingDictionary(RadioButton radioButton)
    {
        if (radioButton == null) return null;

        Operation operationFromDictionary;
        return
            radioButtonToOperation.TryGetValue(radioButton, out operationFromDictionary)
            ? operationFromDictionary
            : (Operation?)null;
    }

    public Operation? SelectedOperation
    {
        get
        {
            // You must include System.Linq in your using block at the top of the file for the following
            // extension methods to be picked up by the compiler:
            // * Enumerable.OfType<T> is an extension method on IEnumerable. 
            // * Enumerable.SingleOrDefault<T> is an extension method on IEnumerable<T>

            RadioButton selectedRadioButton = 
                groupBox1.Controls                                                      // Go through each of the groupbox child controls
                    .OfType<RadioButton>()                                          // Need to convert Controls, which is IEnumerable, to IEnumerable<Control>
                    .Where(radioButton => radioButton.Checked)  // Filter through only the checked radio buttons
                    .SingleOrDefault();                         // Get the single result, or none. (Exception if there are more than one result)

            return GetOperationUsingDictionary(selectedRadioButton);
        }
    }       
}

public enum Operation
{
        Add = 1,
        Subtract = 2,
        Multiply = 3,
        Divide = 4
}