如何实现枚举值映射为类属性值，并通过字符串触发枚举输出对应值

Let's break down how to meet all your requirements step by step. We'll enhance the enum to handle string-to-enum conversion, add a direct mapping to the MaterialWidgets class properties, and ensure you get the expected output.

Step 1: Enhance the Enum with Parsing and Mapping #

First, we'll update MaterialWidgetsEnum to include a method that converts a string to the corresponding enum value, plus a getter that returns the matching static property from MaterialWidgets:

enum MaterialWidgetsEnum {
  radio,
  button,
  navigator;

  // Convert a string to the matching enum value (case-insensitive)
  static MaterialWidgetsEnum? fromString(String value) {
    try {
      return values.firstWhere(
        (enumVal) => enumVal.name.toLowerCase() == value.toLowerCase(),
      );
    } catch (_) {
      return null; // Return null if no match, or throw an error if you prefer strict validation
    }
  }

  // Map the enum value to the corresponding static property in MaterialWidgets
  String get widgetValue {
    switch (this) {
      case MaterialWidgetsEnum.radio:
        return MaterialWidgets.radio;
      case MaterialWidgetsEnum.button:
        return MaterialWidgets.button;
      case MaterialWidgetsEnum.navigator:
        return MaterialWidgets.navigator;
    }
  }
}

class MaterialWidgets {
  static String radio = "radio";
  static String button = "button";
  static String navigator = "navigator";
}

Step 2: Implement the Logic in Main #

Now, in your main function, we'll use the string variable x to get the enum value, then retrieve both the enum's name (for your print requirement) and the corresponding MaterialWidgets property:

void main() {
  // Define your string variable x as required
  String x = "radio";

  // Get the enum value that matches x
  MaterialWidgetsEnum? selectedWidget = MaterialWidgetsEnum.fromString(x);

  if (selectedWidget != null) {
    // Print the enum's name (outputs "radio" as expected)
    print(selectedWidget.name);

    // Get and print the corresponding MaterialWidgets property value
    print(selectedWidget.widgetValue); // Also outputs "radio"
  } else {
    print("No matching widget found for '$x'");
  }
}

Key Explanations: #

• String to Enum Conversion: The fromString method searches through the enum values to find a match for your string x. It’s case-insensitive, so it works even if x is "Radio" or "RADIO".
• Enum to Class Property Mapping: The widgetValue getter uses a switch case to return the exact static string from MaterialWidgets that corresponds to the enum value.
• Expected Output: When you run print(selectedWidget.name), it outputs "radio" because that’s the identifier of the enum member. If you want to directly print the MaterialWidgets property value, use print(selectedWidget.widgetValue).

Alternative: Directly Get Class Property from String #

If you don’t need the enum and just want to fetch the MaterialWidgets property from x, you can use a helper function:

String? getMaterialWidgetValue(String key) {
  switch (key.toLowerCase()) {
    case "radio":
      return MaterialWidgets.radio;
    case "button":
      return MaterialWidgets.button;
    case "navigator":
      return MaterialWidgets.navigator;
    default:
      return null;
  }
}

// Usage in main:
print(getMaterialWidgetValue(x)); // Outputs "radio"

But since your requirements explicitly mention using the enum, the first approach is the best fit.

内容的提问来源于stack exchange，提问作者Mariam Albarghouti