What does enum mean in java

The enum in Java is a type that defines a fixed collection of constants and has the following characteristics: constants are fixed and limited; constants are unique and arranged in the order of declaration; type safety, forcing the use of defined enumeration values. Enumerations can be used to represent states, permission levels, or data types, improving code readability, maintainability, and type safety.

enum in Java

In Java, enum is a special key Word, used to define enumeration types. An enumeration type represents a fixed and limited set of constants.

Definition of enumeration

To define an enumeration type, you can use the following syntax:

<code class="java">enum EnumName {
    CONSTANT1,
    CONSTANT2,
    // 更多常量
}</code>

whereEnumName is the enumeration The name of the enumeration type, CONSTANT1, CONSTANT2, etc. are enumeration constants.

Characteristics of enumerations

• Fixed and limited constants: Enumeration constants are determined at compile time and cannot be modified.
• Uniqueness: Each constant in the enumeration has a unique name.
• Ordering: The enumeration constants are arranged in the order of declaration.
• Type safety: Enumeration types enforce type safety, ensuring that only defined enumeration values ​​can be used.

Usage of enumerations

Enumerations are widely used in Java, including:

• Used to represent status or options (for example: OrderStatus, PaymentStatus)
• is used to indicate the permission level (for example: UserRole, PermissionLevel )
• Used to represent data types (for example: DataType, FieldType)

Advantages of enumeration

Using enumerations has the following advantages:

• Readability and maintainability: Enumerations provide a clear and readable namespace for constants , improving code maintainability.
• Type safety: Enumerations enforce type safety to prevent the use of invalid values.
• Custom methods: Enumerations allow the definition of customized methods and fields, enhancing its functionality.

Example:

Define an enumeration type that represents the order status:

<code class="java">public enum OrderStatus {
    NEW,
    PROCESSING,
    SHIPPED,
    DELIVERED,
    CANCELLED
}</code>

Use enumeration constants:

<code class="java">OrderStatus status = OrderStatus.NEW;</code>

The above is the detailed content of What does enum mean in java. For more information, please follow other related articles on the PHP Chinese website!