V6133. Dereferencing the parameter without a null check. Passing the 'null' value to the 'equals' method should not cause 'NullPointerException'.

The analyzer detected that the overridden equals method lacks a null check for the argument, violating the standard contract.

Look at the example:

@Override
public boolean equals(Object object) {
  if (this == object) {
    return true;
  }

  if (getClass() != object.getClass()) {
    return false;
  }

  Foo another = (Foo) object;
  return type.equals(another.type) &&
         name.equals(another.name);
}

The equals method implements a class match check and field comparison. However, the developer did not take into account that the argument could be a null reference. This may result in a NullPointerException thrown when getClass is called.

According to the documentation, overriding the Object.equals method should return false when a null reference is passed, rather than throw an exception. This is especially important if the class is used in collections.

The fixed example:

@Override
public boolean equals(Object object) {
  if (this == object) {
    return true;
  }

  if (object == null || getClass() != object.getClass()) {
    return false;
  }

  Foo another = (Foo) object;
  return type.equals(another.type) &&
         name.equals(another.name);
}

This diagnostic rule is classified as:

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