Java 简明教程

Java - Enum class

Introduction

Java Enum 类是所有 Java 语言枚举类型的公共基类。

The Java Enum class is the common base class of all Java language enumeration types.

Class Declaration

java.lang.Enum 类声明如下：

Following is the declaration for java.lang.Enum class −

public abstract class Enum<E extends Enum<E>>
   extends Object
      implements Comparable<E>, Serializable

Class constructors

Sr.No.

Constructor & Description

1

protected Enum(String name, int ordinal) This is the single constructor.

Class methods

Sr.No.

Method & Description

1

int compareTo(E o)This method compares this enum with the specified object for order.

2

boolean equals(Object other)This method returns true if the specified object is equal to this enum constant.

3

Class<E> getDeclaringClass()This method returns the Class object corresponding to this enum constant’s enum type.

4

int hashCode()This method returns a hash code for this enum constant.

5

String name()This method returns the name of this enum constant, exactly as declared in its enum declaration.

6

int ordinal()This method returns the ordinal of this enumeration constant (its position in its enum declaration, where the initial constant is assigned an ordinal of zero).

7

String toString()This method returns the name of this enum constant, as contained in the declaration.

8

static <T extends Enum<T>> T valueOf(Class<T> enumType, String name)This method returns the enum constant of the specified enum type with the specified name.

Methods inherited

此类从以下类中继承方法：

This class inherits methods from the following classes −

  1. java.lang.Object

Example

下面的示例展示了在 if 和 switch 语句中使用枚举。

Following example showcases the usage of enum in if and switch statements.

package com.tutorialspoint;

public class EnumDemo {
   public static void main(String args[]) {

      //print an Enum
      System.out.println(Mobile.Motorola);

      Mobile mobile = Mobile.Samsung;
      //Usage in IF statment
      if(mobile == Mobile.Samsung) {
         System.out.println("Matched");
      }
      //Usage in Swith statment
      switch(mobile) {
         case Samsung:
            System.out.println("Samsung");
            break;
         case Nokia:
            System.out.println("Nokia");
            break;
         case Motorola:
            System.out.println("Motorola");
      }
   }
}
enum Mobile {
   Samsung,
   Nokia,
   Motorola
}

Output

让我们编译并运行上述程序，这将生成以下结果 −

Let us compile and run the above program, this will produce the following result −

Motorola
Matched
Samsung