InjectMoreThanOneQualifier
Using more than one qualifier annotation on the same element is not allowed.

Category
INJECT
Severity
ERROR
Maturity

The problem

An element can be qualified by at most one qualifier.

Suppression

Suppress false positives by adding an @SuppressWarnings("InjectMoreThanOneQualifier") annotation to the enclosing element.


Positive examples

MoreThanOneQualifierPositiveCases.java

/*
 * Copyright 2013 Google Inc. All Rights Reserved.
 *
 * 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 com.google.errorprone.bugpatterns.inject.testdata;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.inject.BindingAnnotation;
import java.lang.annotation.Retention;
import javax.inject.Qualifier;

/**
 * @author sgoldfeder@google.com (Steven Goldfeder)
 */
public class MoreThanOneQualifierPositiveCases {


  /**
   * A class in which the class, a constructor, a field, a method, and a method parameter each have
   * two com.google.inject.BindingAnnotation annotations.
   */
  // BUG: Diagnostic contains: remove
  @Foo1 
  // BUG: Diagnostic contains: remove
  @Foo2
  public class TestClass1 {
    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Foo2
    private int n;

    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Foo2
    public TestClass1() {}

    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Foo2
    public void setN(
        // BUG: Diagnostic contains: remove
        @Foo1 
        // BUG: Diagnostic contains: remove
        @Foo2 
        int n) {}
  }

  /**
   * A class in which the class, a constructor, a field, a method, and a method parameter each have
   * two javax.inject.Qualifier annotations.
   */

  // BUG: Diagnostic contains: remove
  @Bar1 
  // BUG: Diagnostic contains: remove
  @Bar2
  public class TestClass2 {
    // BUG: Diagnostic contains: remove
    @Bar1 
    // BUG: Diagnostic contains: remove
    @Bar2
    private int n;

    // BUG: Diagnostic contains: remove
    @Bar1
    // BUG: Diagnostic contains: remove
    @Bar2
    public TestClass2() {}

    // BUG: Diagnostic contains: remove
    @Bar1 
    // BUG: Diagnostic contains: remove
    @Bar2
    public void setN(
        // BUG: Diagnostic contains: remove
        @Bar1 
        // BUG: Diagnostic contains: remove
         @Bar2
         int n) {}
  }

  /**
   * A class in which the class, a constructor, a field, a method, and a method parameter each have
   * one javax.inject.Qualifier annotation and one com.google.inject.BindingAnnotation annotation.
   */

  // BUG: Diagnostic contains: remove
  @Foo1 
  // BUG: Diagnostic contains: remove
  @Bar1
  public class TestClass3 {
    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Bar1
    private int n;

    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Bar1
    public TestClass3() {}

    // BUG: Diagnostic contains: remove
    @Foo1 
    // BUG: Diagnostic contains: remove
    @Bar1
    public void setN(
        // BUG: Diagnostic contains: remove
        @Foo1 
        // BUG: Diagnostic contains: remove
        @Bar1 
        int n) {}
  }

  @Qualifier
  @Retention(RUNTIME)
  public @interface Foo1 {}
  
  @Qualifier
  @Retention(RUNTIME)
  public @interface Foo2 {}
  
  @BindingAnnotation
  @Retention(RUNTIME)
  public @interface Bar1 {}
  
  @BindingAnnotation
  @Retention(RUNTIME)
  public @interface Bar2 {}
}

Negative examples

MoreThanOneQualifierNegativeCases.java

/*
 * Copyright 2013 Google Inc. All Rights Reserved.
 *
 * 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 com.google.errorprone.bugpatterns.inject.testdata;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.inject.BindingAnnotation;
import javax.inject.Qualifier;
import java.lang.annotation.Retention;

/**
 * @author sgoldfeder@google.com (Steven Goldfeder)
 */
public class MoreThanOneQualifierNegativeCases {
  /**
   * A class in with no annotations on any of its members.
   */
  public class TestClass1 {
    private int n;

    public TestClass1() {}

    public void setN(int n) {}
  }

  /**
   * A class in which a single javax.inject.Qualifier annotation is on the class, on a constructor,
   * on a field, on a method, and on a method parameter.
   */
  @Foo
  public class TestClass2 {
    @Foo
    private int n;

    @Foo
    public TestClass2() {}

    @Foo
    public void setN(@Foo int n) {}
  }

  /**
   * A class in which a single com.google.inject.BindingAnnotation annotation is on the class, on a
   * constructor, on a field, on a method, and on a method parameter.
   */
  @Bar
  public class TestClass3 {
    @Bar
    private int n;

    @Bar
    public TestClass3() {}

    @Bar
    public void setN(@Bar int n) {}
  }

  @Qualifier
  @Retention(RUNTIME)
  public @interface Foo {}
  
  @BindingAnnotation
  @Retention(RUNTIME)
  public @interface Bar {}
}