Description Sarah Gerweck 2006-04-12 21:46:54 EDT

When concatenating a string with a possibly null variable using the `+` operator, Eclipse 3.2M5a gives a warning if _Null reference_ is set in Compiler->Errors/Warnings.

Actually, the Java compiler allows nulls in this context and deliberately inserts the string "null". See the Java Language Specification, §15.18.1 [http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#39990].

While some might argue that a warning here is still meritable, I'd suggest a special case in the JLS wins the argument. I would think a checkbox to allow personal preference reasonable; absent a toggle there should be no warning.

The JLS has this special case for a reason. For example, lots of code traps nulls and logs and/or throws an exception indicating the problem:

  if (folderName == null || !FOLDER_PATTERN.matches(folderName))
      throw new BadFolderException("Folder " + folderName + " is invalid");

The whole purpose of the JLS's explicit null handling here is to avoid silly code like this:
          folderName == null ? "null" : folderName