enum valueof_Java Enum valueOf（）方法与示例

妖狐艹你老母 2023-03-05 12:48 54阅读 0赞

enum valueof

## 枚举类valueOf()方法 **(**Enum Class valueOf() method**)** ##

*  **valueOf() method** is available in java.lang package.
    
    **valueOf()方法**在java.lang包中可用。
 *  **valueOf() method** is used to retrieve the enum constants of the given parameter en\_ty(enum type) with the given parameter en\_name(enum name) and we need to remember one thing the enum name specified in the method must be the same as declared as enum constant in this enum type.
    
    **valueOf()方法**用于检索具有给定参数en\_name(枚举名称)的给定参数en\_ty(枚举类型)的枚举常量，我们需要记住一件事，该方法中指定的枚举名称必须与声明为相同此枚举类型的枚举常量。
 *  **valueOf() method** is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
    
    **valueOf()方法**是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
 *  **valueOf() method** may throw an exception at the time of retrieving enum constants:
    
    在检索枚举常量时， **valueOf()方法**可能会引发异常：
    
     *  **IllegalArgumentException**: When the given enum type does not contain enum constants with the given name.**IllegalArgumentException** ：当给定的枚举类型不包含具有给定名称的枚举常量时。
     *  **NullPointerException**: When the given first parameter represents null.**NullPointerException** ：当给定的第一个参数表示null时。

**Syntax:**

**句法：**

public static T valueOf(Class<T> en_ty , String en_name);

**Parameter(s):**

**参数：**

*  Class<T> en\_ty – represents the Class object of the enum type which return a constant.
    
    Class <T> en\_ty –表示枚举类型的Class对象，该对象返回一个常量。
 *  String en\_name – represents the name of enum constants.
    
    字符串en\_name –表示枚举常量的名称。

**Return value:**

**返回值：**

The return type of this method is T, it returns enum constant along with the given enum name.

此方法的返回类型为T ，它返回枚举常量以及给定的枚举名称。

**Example:**

**例：**

// Java program to demonstrate the example 
    // of T valueOf(Class<T> en_ty , String en_name)
    // method of Enum 
    
    enum Month {
        
        JAN,
        FEB,
        MAR,
        APR,
        MAY;
    }
    
    public class ValueOf {
        
        public static void main(String args[]) {
        
    
            Month m1 = Month.valueOf("JAN");
            Month m2 = Month.valueOf("FEB");
            Month m3 = Month.valueOf("MAR");
            Month m4 = Month.valueOf("APR");
            Month m5 = Month.valueOf("MAY");
    
            System.out.println("Display value: ");
    
            // By using valueOf() method is to return the value of
            // enum constant 
            System.out.println("Month.valueOf(JAN) " + " " + m1.toString());
            System.out.println("Month.valueOf(FEB) " + " " + m2.toString());
            System.out.println("Month.valueOf(MAR)" + " " + m3.toString());
            System.out.println("Month.valueOf(APR)" + " " + m4.toString());
            System.out.println("Month.valueOf(MAY)" + " " + m5.toString());
        }
    }

**Output**

**输出量**

Display value: 
    Month.valueOf(JAN)  JAN
    Month.valueOf(FEB)  FEB
    Month.valueOf(MAR) MAR
    Month.valueOf(APR) APR
    Month.valueOf(MAY) MAY

> 翻译自: [https://www.includehelp.com/java/enum-valueof-method-with-example.aspx][https_www.includehelp.com_java_enum-valueof-method-with-example.aspx]

enum valueof

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