001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.lang;
018
019import java.lang.annotation.Documented;
020import java.lang.annotation.ElementType;
021import java.lang.annotation.Retention;
022import java.lang.annotation.RetentionPolicy;
023import java.lang.annotation.Target;
024
025import javax.annotation.Nonnull;
026import javax.annotation.meta.TypeQualifierNickname;
027
028/**
029 * A common Spring annotation to declare that annotated elements cannot be {@code null}.
030 *
031 * <p>Leverages JSR-305 meta-annotations to indicate nullability in Java to common
032 * tools with JSR-305 support and used by Kotlin to infer nullability of Spring API.
033 *
034 * <p>Should be used at parameter, return value, and field level. Method overrides should
035 * repeat parent {@code @NonNull} annotations unless they behave differently.
036 *
037 * <p>Use {@code @NonNullApi} (scope = parameters + return values) and/or {@code @NonNullFields}
038 * (scope = fields) to set the default behavior to non-nullable in order to avoid annotating
039 * your whole codebase with {@code @NonNull}.
040 *
041 * @author Sebastien Deleuze
042 * @author Juergen Hoeller
043 * @since 5.0
044 * @see NonNullApi
045 * @see NonNullFields
046 * @see Nullable
047 */
048@Target({ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD})
049@Retention(RetentionPolicy.RUNTIME)
050@Documented
051@Nonnull
052@TypeQualifierNickname
053public @interface NonNull {
054}