Java 如何抑制“未知枚举常量”警告？
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How to suppress "unknown enum constant" warnings?
提问by Gili
The Checkers Frameworkreferences java.lang.annotation.ElementType.TYPE_USEwhich was added in JDK8. When I use it under JDK7, I get the following warning:
java.lang.annotation.ElementType.TYPE_USEJDK8 中添加的 Checkers Framework引用。当我在 JDK7 下使用它时，我收到以下警告：
unknown enum constant java.lang.annotation.ElementType.TYPE_USE
unknown enum constant java.lang.annotation.ElementType.TYPE_USE
This is a reasonable warning, but how do I suppress it for cases I believe are harmless?
这是一个合理的警告，但是对于我认为无害的情况，我该如何抑制它？
采纳答案by Gili
It turns out there is no such thing as a harmless unknown enum constant. Once I got past the compiler warnings, I ran into exceptions at runtime:
事实证明，没有无害的未知枚举常量这样的东西。一旦我通过编译器警告，我在运行时遇到了异常：
java.lang.ArrayStoreException: sun.reflect.annotation.EnumConstantNotPresentExceptionProxy
at sun.reflect.annotation.AnnotationParser.parseEnumArray(AnnotationParser.java:693) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseArray(AnnotationParser.java:482) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseMemberValue(AnnotationParser.java:306) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:241) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:88) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70) ~[na:1.7.0_40]
at java.lang.Class.initAnnotationsIfNecessary(Class.java:3168) ~[na:1.7.0_40]
at java.lang.Class.getAnnotation(Class.java:3127) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationType.<init>(AnnotationType.java:131) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationType.getInstance(AnnotationType.java:84) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:221) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:88) ~[na:1.7.0_40]
at sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70) ~[na:1.7.0_40]
at java.lang.reflect.Method.declaredAnnotations(Method.java:714) ~[na:1.7.0_40]
at java.lang.reflect.Method.getAnnotation(Method.java:700) ~[na:1.7.0_40]
at com.google.inject.spi.InjectionPoint.getAtInject(InjectionPoint.java:466) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.spi.InjectionPoint.getInjectionPoints(InjectionPoint.java:664) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.spi.InjectionPoint.forInstanceMethodsAndFields(InjectionPoint.java:356) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.MembersInjectorStore.createWithListeners(MembersInjectorStore.java:90) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.MembersInjectorStore.access unknown enum constant java.lang.annotation.ElementType.TYPE_USE
0(MembersInjectorStore.java:34) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.MembersInjectorStore.create(MembersInjectorStore.java:42) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.MembersInjectorStore.create(MembersInjectorStore.java:39) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.FailableCache.apply(FailableCache.java:39) ~[guice-3.0-no_aop.jar:na]
at com.google.inject.internal.util.$MapMaker$StrategyImpl.compute(MapMaker.java:549) ~[guice-3.0-no_aop.jar:na]
... 102 common frames omitted
Meaning, any code that uses java.lang.reflect.Method.getAnnotation()will fail at runtime.
意思是，任何使用的代码java.lang.reflect.Method.getAnnotation()都会在运行时失败。
In my case, this issue was caused by https://code.google.com/p/checker-framework/issues/detail?id=255
就我而言，此问题是由https://code.google.com/p/checker-framework/issues/detail?id=255引起的
回答by mernst
If you get this compile-time error:
如果您收到此编译时错误：
##代码##then you are compiling using a Java 7 JDK, but your code references an enum constant that is only defined in the Java 8 JDK. The problem might be that your code uses a library that references the enum constant. In particular, the type annotations shipped with the Checker Framework reference ElementType.TYPE_USE. You can use the Checker Framework, but still compile and run your code in a Java 7 JVM, by following the instructions in section "Class-file compatibility with Java 7" of the Checker Framework manual.
那么您正在使用 Java 7 JDK 进行编译，但是您的代码引用了一个仅在 Java 8 JDK 中定义的枚举常量。问题可能在于您的代码使用了一个引用枚举常量的库。特别是，Checker Framework 附带的类型注释引用ElementType.TYPE_USE。您可以使用 Checker 框架，但仍可以按照 Checker 框架手册的“类文件与 Java 7 的兼容性”部分中的说明在 Java 7 JVM 中编译和运行您的代码。
