Hadoop... Text.toString() conversion problems

Hi everyone,

I hope this is the right place for my question. If not, please, feel free to ignore it  ;) and I'm sorry for any inconvenience made :(

I'm writing a simple program for enumerating triangles in directed graphs for my project. First, for each input arc (e.g. a b, b c, c a, note: a tab symbol serves as a delimiter) I want my map function output
the following pairs ([a, to_b], [b, from_a], [a_b, -1]):

 public void map(LongWritable key, Text value,

                OutputCollector/span>Text, Text> output,

                Reporter reporter) throws IOException {


  String line = value.toString();

  String [] tokens = line.split("    ");


  output.collect(new Text(tokens[0]), new Text("to_"+tokens[1]));

  output.collect(new Text(tokens[1]), new Text("from_"+tokens[0]));

  output.collect(new Text(tokens[0]+"_"+tokens[1]), new Text("-1"));


}

Now my reduce function is supposed to cross join all pairs that have both to_'s and from_'s and to simply propogate any other pairs whose keys contain "_".

      public void reduce(Text key, Iterator/span>Text> values,

                   OutputCollector/span>Text, Text> output,

                   Reporter reporter) throws IOException {


  String key_s = key.toString();


  if (key_s.indexOf("_")>0)

      output.collect(key, new Text("completed"));


   else {

           HashMap /span>String, ArrayList/span>String>> lists = new HashMap /span>String, ArrayList/span>String>> ();    


          while (values.hasNext()) {


              String line = values.next().toString();


              String[] tokens = line.split("_");

              if (!lists.containsKey(tokens[0])) {

                   lists.put(tokens[0], new ArrayList/span>String>());

              }
           lists.get(tokens[0]).add(tokens[1]);     

          }

          for (String t : lists.get("to"))

               for (String f : lists.get("from"))

                  output.collect(new Text(t+"_"+f), key); 



  }

} 

And this is where the most exciting stuff happens. tokens[1] yields an ArrayOutOfBounds exception. If you scroll up, you can see that by this point the iterator should give values like "to_a", "from_b",
"to_b", etc... if I just output these values, everything looks ok and I
have "to_a", "from_b". But split() don't work at all, moreover
line.length() is always 1 and indexOf("_") returns -1! The very same
indexOf WORKS PERFECTLY for keys... where we have pairs whose keys
contain "_" and look like "a_b", "b_c"

I'm really puzzled with all this. MapReduce is supposed to save lives making everything simple. Instead I spent several hours to just spot  this...

I'd really appreciate your help, guys!!! Thanks in advance!