项目出现警告:未知的枚举常量 javax.annotation.meta.When.MAYBE

原创 创建时间:2019-04-19 访问量:2525 赞:1 踩:0

Warning:java: 未知的枚举常量 javax.annotation.meta.When.MAYBE

原因: 找不到javax.annotation.meta.When的类文件

出现这个警告,是由于Spring框架中的某些注解如Nullable引入了这些注解,如下所示:

/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.lang;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import javax.annotation.Nonnull;
import javax.annotation.meta.TypeQualifierNickname;
import javax.annotation.meta.When;

/**
 * A common Spring annotation to declare that annotated elements can be {@code null} under
 * some circumstance. Leverages JSR 305 meta-annotations to indicate nullability in Java
 * to common tools with JSR 305 support and used by Kotlin to infer nullability of Spring API.
 *
 * <p>Should be used at parameter, return value, and field level. Methods override should
 * repeat parent {@code @Nullable} annotations unless they behave differently.
 *
 * <p>Can be used in association with {@code @NonNullApi} or {@code @NonNullFields} to
 * override the default non-nullable semantic to nullable.
 *
 * @author Sebastien Deleuze
 * @author Juergen Hoeller
 * @since 5.0
 * @see NonNullApi
 * @see NonNullFields
 * @see NonNull
 */
@Target({ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Nonnull(when = When.MAYBE)
@TypeQualifierNickname
public @interface Nullable {
}

上面的类在IDEA中检测不到javax.annotation.meta包中的类,所以出现警告。

加入相关的jar包即可:

compile 'com.google.code.findbugs:annotations:3.0.1'

这样就可以消除警告了。

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