Re: "final" bug??

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 02 May 2009 17:15:21 -0400

Message-ID:

<gtid5a$lil$1@news.albasani.net>

Roedy Green wrote:

Consider the following code

static final String allpads;

    static
        {
        try
            {
            allPads = HunkIO.readEntireFile( ALLPADS_FILE );
            }
        catch ( IOException e )
            {
            err.println( "Unable to access allPads.pad" );
            allPads = null;
            }
        }

According to the IntelliJ inspector, this allPads should be final.
But according to Javac, it should not, claiming I might be trying to
redefine a final.

Which is correct and why?

I suspect javac is correct, according to how I read s. 16.2.15 of the JLS. It
seems to hinge on whether 'allPads' is definitely assigned or definitely
unassigned after the 'readEntireFile()' assignment statement. S. 16.8 seems
to apply, also. The way I read the spec, you cannot say that 'allPad' is
definitely unassigned at the end of the 'try' block, therefore it is not
definitely unassigned before the 'catch' block, therefore the assignment
inside the 'catch' block is potentially a re-assignment.

Regardless, the fix is simple:

  static final String allPads;
  static
  {
    String ap;
    try
    {
      aP = HunkIO.readEntireFile( ALLPADS_FILE );
    }
    catch ( IOException e )
    {
      err.println( "Unable to access "+ ALLPADS_FILE );
      aP = null;
    }
    allPads = ap;
  }

--
Lew