V6067. Two or more case-branches perform the same actions.

The analyzer has detected a situation where different case labels of a switch statement contain the same code. Those are often redundant code, which could be improved by merging the labels. On the other hand, identical code fragments may also result from the use of the copy-paste technique, in which case they are errors rather than simply redundant code.

Consider the following example of redundant code:

public static String getSymmetricCipherName(SymmetricKeyAlgorithmTags tag)
{
    switch (tag)
    {
        case DES:
            return "DES";
        case AES_128:
            return "AES";
        case AES_192:
            return "AES";
        case AES_256:
            return "AES";
        case CAMELLIA_128:
            return "Camellia";
        case CAMELLIA_192:
            return "Camellia";
        case CAMELLIA_256:
            return "Camellia";
        case TWOFISH:
            return "Twofish";
        default:
            throw new IllegalArgumentException("....");
    }
}

In real projects there are cases when it is needed to perform equal actions. In order to make the code more readable, one can write the code more densely:

public static String getSymmetricCipherName(SymmetricKeyAlgorithmTags tag)
{
    switch (tag)
    {
        case DES:
            return "DES";
        case AES_128:
        case AES_192:
        case AES_256:
            return "AES";
        case CAMELLIA_128:
        case CAMELLIA_192:
        case CAMELLIA_256:
            return "Camellia";
        case TWOFISH:
            return "Twofish";
        default:
            throw new IllegalArgumentException("....");
    }
}

The next example is taken from a real application and demonstrates faulty behavior resulting from a typo:

protected boolean condition(Actor actor) throws ....
{
  ....
  if (fieldValue instanceof Number) 
  {
    ....
    switch (tokens[2]) 
    {
      case "=":
      case "==":
        passing = (Double) fieldValue
                  == 
                  Double.parseDouble(secondValue);
        break;
      case "!":
      case "!=":
        passing = (Double) fieldValue 
                  ==
                  Double.parseDouble(secondValue);
        break;
      case "<=":
        passing = ((Number) fieldValue).doubleValue() 
                  <=
                  Double.parseDouble(secondValue);
        break;
      ....
    }
   ....
  }
  ....
}

There is a typo in the code of the marks '!' and '!=' which apparently occurred due to copy-paste. After viewing other case branches, we can conclude that the comparison operator '!=' had to be used instead of '=='.

Fixed code:

protected boolean condition(Actor actor) throws ....
{
  ....
  if (fieldValue instanceof Number) 
  {
    ....
    switch (tokens[2]) 
    {
      case "=":
      case "==":
        passing = (Double) fieldValue
                  ==
                  Double.parseDouble(secondValue);
        break;
      case "!":
      case "!=":
        passing = (Double) fieldValue 
                  !=
                  Double.parseDouble(secondValue);
        break;
      case "<=":
        passing = ((Number) fieldValue).doubleValue() 
                  <=
                  Double.parseDouble(secondValue);
        break;
      ....
    }
   ....
  }
  ....
}

This diagnostic is classified as: