如果我在编译时不知道该类，那么如何获得枚举值？ [英] How do I get the value of an Enum, if I don't know the class at compile time?

问题描述

我正在尝试执行以下操作：

I'm trying to do the following:

Class<?> cls = unknownClass;
if(cls.isEnum()){
    @SuppressWarnings("unchecked")
    Class<? extends Enum<?>> enumClass = (Class<? extends Enum<?>>) cls;
    Object val = Enum.valueOf(enumClass, "NAME1");
}

但是我收到以下错误：

Bound mismatch: The generic method valueOf(Class<T>, String) of type Enum<E> is 
not applicable for the arguments (Class<capture#5-of ? extends Enum<?>>, String). 
The inferred type capture#5-of ? extends Enum<?> is not a valid substitute for 
the bounded parameter <T extends Enum<T>>   

有人可以告诉我我做错了什么？

Can someone tell me what I am doing wrong?

推荐答案

鉴于演员不会真正正在检查内容，我会使用完整的原始版本：

Given that the cast won't really be checking things, I'd go with the completely raw version:

if (cls.isEnum()){
    @SuppressWarnings("unchecked")
    Object val = Enum.valueOf(cls, "NAME1");
}

似乎有效。完整的例子：

That seems to work. Complete example:

public class Test
{
    enum Foo
    {
        BAR, BAZ
    }


    public static void main(String[] args)
    {
        @SuppressWarnings("rawtypes")
        Class cls = Foo.class;

        if (cls.isEnum())
        {        
            @SuppressWarnings("unchecked")
            Object value = Enum.valueOf(cls, "BAR");
            System.out.println(value);
        }
    }
}

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