java 从枚举类型和序号中获取枚举值
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Get enum value from enum type and ordinal
提问by Distortum
public <E extends Enum> E decode(java.lang.reflect.Field field, int ordinal) {
// TODO
}
Assuming field.getType().isEnum()is true, how would I produce the enum value for the given ordinal?
假设field.getType().isEnum()是true，我将如何生成给定序数的枚举值？
回答by Louis Wasserman
field.getType().getEnumConstants()[ordinal]
suffices. One line; straightforward enough.
就够了。一条线; 够直接了。
回答by Pshemo
To get what you want you need to invoke YourEnum.values()[ordinal]. You can do it with reflection like this:
要获得您想要的东西，您需要调用YourEnum.values()[ordinal]. 你可以用这样的反射来做到这一点：
public static <E extends Enum<E>> E decode(Field field, int ordinal) {
try {
Class<?> myEnum = field.getType();
Method valuesMethod = myEnum.getMethod("values");
Object arrayWithEnumValies = valuesMethod.invoke(myEnum);
return (E) Array.get(arrayWithEnumValies, ordinal);
} catch (NoSuchMethodException | SecurityException
| IllegalAccessException | IllegalArgumentException
| InvocationTargetException e) {
e.printStackTrace();
}
return null;
}
UPDATE
更新
As @LouisWasserman pointed in his comment there is much simpler way
正如@LouisWasserman 在他的评论中指出的那样，有更简单的方法
public static <E extends Enum<E>> E decode(Field field, int ordinal) {
return (E) field.getType().getEnumConstants()[ordinal];
}
回答by AlexWien
ExampleTypeEnum value = ExampleTypeEnum.values()[ordinal]
回答by Sam Ginrich
According to title, suggest
根据标题，建议
public <E extends Enum> E decode(Class<?> enumType, int ordinal)
{
return enumType.getEnumConstants()[ordinal];
}
to be called by
被称为
YourEnum enumVal = decode(YourEnum.class, ordinal)
