PrimitiveArrayPassedToVarargsMethod
Passing a primitive array to a varargs method is usually wrong

Category
JDK
Severity
WARNING
Maturity

The problem

When you pass a primitive array as the only argument to a varargs method, the primitive array is autoboxed into a single-element Object array. This is usually not what was intended.

Suppression

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


Positive examples

PrimitiveArrayPassedToVarargsMethodPositiveCases.java

/*
 * Copyright 2014 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.testdata;

import java.util.Arrays;

import com.google.common.base.Objects;

/**
 * @author eaftan@google.com (Eddie Aftandilian)
 */
public class PrimitiveArrayPassedToVarargsMethodPositiveCases {
  
  public void objectVarargsMethod(Object... objs) {}
 
  public <T> void genericVarargsMethod(T... genericArrays) {}
  
  public void objectVarargsMethodWithMultipleParams(Object obj1, Object... objs) {}
  
  public void doIt() {
    int[] intArray = {1, 2, 3};
    
    // BUG: Diagnostic contains: 
    objectVarargsMethod(intArray);
    
    // BUG: Diagnostic contains: 
    genericVarargsMethod(intArray);
    
    // BUG: Diagnostic contains: 
    objectVarargsMethodWithMultipleParams(new Object(), intArray);
    
    // BUG: Diagnostic contains: 
    Arrays.asList(intArray);
  }
}

Negative examples

PrimitiveArrayPassedToVarargsMethodNegativeCases.java

/*
 * Copyright 2014 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.testdata;

import com.google.common.base.Objects;

/**
 * @author eaftan@google.com (Eddie Aftandilian)
 */
public class PrimitiveArrayPassedToVarargsMethodNegativeCases {
  
  public void intVarargsMethod(int... ints) {} 
  
  public void intArrayVarargsMethod(int[]... intArrays) {}
  
  public void objectVarargsMethodWithMultipleParams(Object obj1, Object... objs) {}
  
  public void doIt() {
    int[] intArray = {1, 2, 3};
    
    intVarargsMethod(intArray);
    intArrayVarargsMethod(intArray);
    objectVarargsMethodWithMultipleParams(new Object());
  }
}