/*
 * Copyright (C) 2009 The JSR-330 Expert Group
 *
 * 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 javax.inject;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import java.lang.annotation.Documented;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;

Identifies qualifier annotations. Anyone can define a new qualifier. A qualifier annotation:
  • is annotated with @Qualifier, @Retention(RUNTIME), and typically @Documented.
  • can have attributes.
  • may be part of the public API, much like the dependency type, but unlike implementation types which needn't be part of the public API.
  • may have restricted usage if annotated with @Target. While this specification covers applying qualifiers to fields and parameters only, some injector configurations might use qualifier annotations in other places (on methods or classes for example).

For example:

  @java.lang.annotation.Documented
  @java.lang.annotation.Retention(RUNTIME)
  @javax.inject.Qualifier
  public @interface Leather {
    Color color() default Color.TAN;
    public enum Color { RED, BLACK, TAN }
  }
See Also:
/** * Identifies qualifier annotations. Anyone can define a new qualifier. A * qualifier annotation: * * <ul> * <li>is annotated with {@code @Qualifier}, {@code @Retention(RUNTIME)}, * and typically {@code @Documented}.</li> * <li>can have attributes.</li> * <li>may be part of the public API, much like the dependency type, but * unlike implementation types which needn't be part of the public * API.</li> * <li>may have restricted usage if annotated with {@code @Target}. While * this specification covers applying qualifiers to fields and * parameters only, some injector configurations might use qualifier * annotations in other places (on methods or classes for example).</li> * </ul> * * <p>For example: * * <pre> * &#064;java.lang.annotation.Documented * &#064;java.lang.annotation.Retention(RUNTIME) * &#064;javax.inject.Qualifier * public @interface Leather { * Color color() default Color.TAN; * public enum Color { RED, BLACK, TAN } * }</pre> * * @see javax.inject.Named @Named */
@Target(ANNOTATION_TYPE) @Retention(RUNTIME) @Documented public @interface Qualifier {}