GuiceAssistedParameters
A constructor cannot have two @Assisted parameters of the same type unless they are disambiguated with named @Assisted annotations.

Category
Severity
ERROR
Maturity

The problem

See https://google.github.io/guice/api-docs/latest/javadoc/com/google/inject/assistedinject/FactoryModuleBuilder.html

Suppression

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


Positive examples

AssistedParametersPositiveCases.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.guice.testdata;

import com.google.inject.assistedinject.Assisted;
import java.util.List;
import javax.inject.Inject;

/**
* @author sgoldfeder@google.com(Steven Goldfeder)
*/

public class AssistedParametersPositiveCases {

/**
* Class has constructor with two @Assisted parameters of the same type.
*/

public class TestClass1 {
@Inject
// BUG: Diagnostic contains: java.lang.String: x, y
public TestClass1(int n, @Assisted String x, @Assisted String y, int z) {}

@Inject
// BUG: Diagnostic contains: java.lang.String, @Assisted("baz"): x, z
public TestClass1(
@Assisted("foo") int a,
@Assisted("foo") int b,
@Assisted("baz") String x,
@Assisted("baz") String z) {}
}

/**
* Class has constructor with two @Assisted parameters of the same type and same value.
*/

public class TestClass2 {
@Inject
// BUG: Diagnostic contains: int, @Assisted("foo"): x, y
public TestClass2(int n, @Assisted("foo") int x, @Assisted("foo") int y, String z) {}
}

/**
* Class has constructor with two @Assisted parameters of the same parameterized type.
*/

public class TestClass3 {
private static final String FOO = "foo";

@Inject
// BUG: Diagnostic contains: java.util.List<java.lang.String>, @Assisted("foo"): x, y
public TestClass3(
int n, @Assisted("foo") List<String> x, @Assisted(FOO) List<String> y, String z) {}

@Inject
// BUG: Diagnostic contains: int, @Assisted("bar"): x, y
public TestClass3(
@Assisted() int n, @Assisted("bar") int x, @Assisted("bar") int y, String z) {}
}

class GenericClass<T> {
@Inject
// BUG: Diagnostic contains: T: a, b
GenericClass(@Assisted T a, @Assisted T b) {}

@Inject
// BUG: Diagnostic contains: int: a, b
GenericClass(@Assisted Integer a, @Assisted int b) {}
}
}

Negative examples

AssistedParametersNegativeCases.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.guice.testdata;

import com.google.inject.assistedinject.Assisted;
import java.util.List;
import javax.inject.Inject;

/**
* @author sgoldfeder@google.com (Steven Goldfeder)
*/

public class AssistedParametersNegativeCases {

/**
* Class has constructor with two @Assisted parameters of different types.
*/

public class TestClass1 {
@Inject
public TestClass1(@Assisted int x, @Assisted String y, long z) {}
}

/**
* Class has constructor with two @Assisted parameters, but the @Assisted annotations have
* different values.
*/

public class TestClass2 {
@Inject
public TestClass2(@Assisted("foo") int x, @Assisted("bar") int y, String z) {}
}

/**
* Class has constructor with one @Assisted parameter with no value specified and another
* parameter of the same type.
*/

public class TestClass3 {
@Inject
public TestClass3(@Assisted int x, int y, String z) {}
}

/**
* Class has constructor with one @Assisted parameters with a value specified and and another
* parameter of the same type.
*/

public class TestClass4 {
@Inject
public TestClass4(@Assisted("foo") int x, int y, String z) {}
}

/**
* Class has constructor with two @Assisted parameters with the same value and generic type and
* different type parameters.
*/

public class TestClass5 {
@Inject
public TestClass5(@Assisted("foo") List<String> x, @Assisted("foo") List<Integer> y, String z) {}
}
}