How do Java enum types work with reflection mechanism?

Answer: Java enumeration types combined with the reflection mechanism can dynamically obtain enumeration information and create instances. Detailed description: The reflection mechanism allows Java programs to inspect and modify their own state. Enumeration types can represent fixed values ​​and provide advanced access when combined with reflection. We can use reflection to obtain enumeration values, type information and create enumeration instances.

Java enumeration types and reflection mechanism

Background

Java Enumeration A type is a special data type that represents a known, fixed set of values. When used in conjunction with the reflection mechanism, enumerations can provide high-level access to enum instances and related information.

Reflection mechanism

Reflection allows a Java program to examine and modify its own state. It provides a series of APIs that can be used to:

• Get information about a class, including its fields, methods and annotations
• Create a new instance or call a method
• Modify Accessibility of fields or methods

Enumeration and reflection

We can use reflection to dynamically obtain information about the enumeration class and its constants. This is useful in the following situations:

• Getting enumeration values: We can get all the constants of an enumeration using the Class.getEnumConstants() method as EnumConstant Array.
• Get enumeration type information: Enum.getClass() The method returns the Class object of the enumeration class, which we can use to retrieve More information, such as fields and methods.
• Create an enumeration instance: Using the Enum.valueOf(Class, String) method, we can create an enumeration instance by its name.

Practical case

Suppose we have a Season enumeration, which defines the constants of the season:

public enum Season {
    SPRING,
    SUMMER,
    AUTUMN,
    WINTER
}

Get enumeration constants:

Class<Season> seasonClass = Season.class;
EnumConstant<Season>[] constants = seasonClass.getEnumConstants();

Get enumeration type information:

Field[] fields = seasonClass.getDeclaredFields();
Method[] methods = seasonClass.getDeclaredMethods();

Create enumeration instance:

Season spring = Enum.valueOf(Season.class, "SPRING");

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