EnumsUtil

This tutorial provides an overview of the EnumsUtil class, which is part of the lightweight-component/aj-util library. The EnumsUtil class provides a way to retrieve enum instances and their associated messages (or other values) based on a code, when the enums implement the IEnum interface. This is particularly useful when you have enums where each constant has a code and a corresponding descriptive message, and you need to look up the enum by its code.

The IEnum Interface

Before diving into EnumsUtil, let's understand the IEnum interface. Enums that work with EnumsUtil are expected to implement this interface:

package com.ajaxjs.util.enums;

public interface IEnum<E, V> {
    E getCode();
    V getMsg();
}

Where:

• E is the type of the code (e.g., String, Integer).
• V is the type of the message (or associated value).

Methods

1. of(E code, Class<T> clz)

Retrieves an Optional<T> containing the enum instance that matches the given code.

• Parameters:
  • code: The code to search for.
  • clz: The Class object representing the enum type.
• Returns: An Optional<T> containing the enum instance if found, or Optional.empty() if no matching enum is found.

Example:

Optional<TypeEnum> type = EnumsUtil.of("YES", TypeEnum.class);
if (type.isPresent()) {
    TypeEnum enumValue = type.get();
    System.out.println("Found enum: " + enumValue);
} else {
    System.out.println("Enum not found for code YES");
}

2. ofMsg(E code, Class<T> cla)

Retrieves the message (or associated value) of the enum instance that matches the given code.

• Parameters:
  • code: The code to search for.
  • cla: The Class object representing the enum type.
• Returns: The message (or associated value) of the enum instance, or null if no matching enum is found.

Example:

String message = EnumsUtil.ofMsg("YES", TypeEnum.class);
System.out.println("Message for YES: " + message); // Output: Message for YES: 是

Usage Example

Here's a complete example, including the enum definition:

import com.ajaxjs.util.enums.EnumsUtil;
import com.ajaxjs.util.enums.IEnum;
import java.util.Optional;

public class Example {

    public enum TypeEnum implements IEnum<String, String> {
        YES("YES", "是"),
        NO("NO", "否");

        private final String code;
        private final String msg;

        TypeEnum(String code, String msg) {
            this.code = code;
            this.msg = msg;
        }

        @Override
        public String getCode() {
            return this.code;
        }

        @Override
        public String getMsg() {
            return this.msg;
        }
    }

    public static void main(String[] args) {
        Optional<TypeEnum> type = EnumsUtil.of("YES", TypeEnum.class);
        if (type.isPresent()) {
            TypeEnum enumValue = type.get();
            System.out.println("Found enum: " + enumValue);
            System.out.println("Code: " + enumValue.getCode());
            System.out.println("Message: " + enumValue.getMsg());
        } else {
            System.out.println("Enum not found for code YES");
        }

        String message = EnumsUtil.ofMsg("NO", TypeEnum.class);
        System.out.println("Message for NO: " + message);
    }
}

Unit Test Example

Here's the unit test code:

package com.ajaxjs.util.enums;

import org.junit.jupiter.api.Test;

public class TestEnumsUtil {
    public enum TypeEnum implements IEnum<String, String> {
        YES("YES", "是"),
        NO("NO", "否");

        private final String code;
        private final String msg;

        TypeEnum(String code, String msg) {
            this.code = code;
            this.msg = msg;
        }

        @Override
        public String getCode() {
            return this.code;
        }

        @Override
        public String getMsg() {
            return this.msg;
        }
    }

    @Test
    public void test() {
        System.out.println(EnumsUtil.ofMsg("YES", TypeEnum.class));
    }
}

Conclusion

The EnumsUtil class provides a convenient way to work with enums that implement the IEnum interface, allowing you to easily retrieve enum instances and their associated values based on a code. This can be particularly useful in applications where you need to map codes to enum values and their corresponding messages.

Important Note: The search results may be incomplete. To view more results, you can use this link: https://github.com/lightweight-component/aj-util/search?q=symbol%3AEnumsUtil in the GitHub UI.