注释属性Min.value的值必须是一个常量表达式 [英] The value for annotation attribute Min.value must be a constant expression

问题描述

Eclipse不断给我错误:

Eclipse keeps giving me the error:

The value for annotation attribute Min.value must be a constant expression

但是我绝对可以给注解一个常量.

But I am most definitely giving the annotation a constant.

private static final int MIN_YEAR = Calendar.getInstance().get(Calendar.YEAR) - 1;

@Min(MIN_YEAR)

如果我将其更改为

private static final int MIN_YEAR = 2013;

很高兴，但我不必这样做.有人知道为什么如果我的MIN_YEAR常量是用评估表达式而不是纯数字声明的，为什么我的MIN_YEAR常量不被视为常量?

It's perfectly happy, but I shouldn't have to do that. Does anyone know why or how my MIN_YEAR constant isn't considered a constant if it's declared with an evaluated expression instead of a plain number?

推荐答案

表达式

private static final int MIN_YEAR = Calendar.getInstance().get(Calendar.YEAR) - 1;

仅在运行时确定，但

private static final int MIN_YEAR = 2013;

是在编译时确定的，因此允许使用，因为注释中的值应在编译时而不是在运行时解析.

is determined in compilation time, so it's allowed since the values in the annotations should be resolved at compilation time and not runtime.

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