Workin with threads

Question

Hello all!
I am writing a project that works with nlp(natural language parser),I am using the stanford parser.
I create a thread pool that takes sentances and run the parser with them.
when I create one thread its all works fine but when I create more I get errors.
the "test" procedure is findings words that have some connections.
If I do an synchronized its supposed to work like one thread but still I get errors.
My problem is that I have errors on this code:
public synchronized String test(String s,LexicalizedParser lp ){
    if (s.isEmpty()) return "";
    if (s.length()>80) return "";
    System.out.println(s);
    String[] sent = s.split(" ");
Tree parse = (Tree) lp.apply(Arrays.asList(sent));
TreebankLanguagePack tlp = new PennTreebankLanguagePack();
GrammaticalStructureFactory gsf = tlp.grammaticalStructureFactory();
GrammaticalStructure gs = gsf.newGrammaticalStructure(parse);
Collection tdl = gs.typedDependenciesCollapsed();
List list = new ArrayList(tdl);
//for (int i=0;i<list.size();i++)
//System.out.println(list.get(1).toString());
//remove scops and numbers like sbj(screen-4,good-6)->screen good
Pattern p = Pattern.compile(".*\\((.*?)\\-\\d+,(.*?)\\-\\d+\\).*");
       if (list.size()>2){
    // Split input with the pattern
        Matcher m = p.matcher(list.get(1).toString());
        //check if the result have more than  1 groups
       if (m.find()&& m.groupCount()>1){
           if (m.groupCount()>1)
               System.out.println(list);
return  m.group(1)+m.group(2);
        return "";
}the errors are:
at blogsOpinions.ThreadPoolTest$1.run(ThreadPoolTest.java:50)
at blogsOpinions.ThreadPool$PooledThread.run(ThreadPoolTest.java:196)
Recovering using fall through strategy: will construct an (X ...) tree.
Exception in thread "PooledThread-6" java.lang.ClassCastException: java.lang.String cannot be cast to edu.stanford.nlp.ling.HasWord
at edu.stanford.nlp.parser.lexparser.LexicalizedParser.apply(LexicalizedParser.java:289)
java.lang.NullPointerException
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:25)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:33)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:33)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:33)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:33)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTreeHelper(Debinarizer.java:33)
at edu.stanford.nlp.parser.lexparser.Debinarizer.transformTree(Debinarizer.java:46)
thanks!

Answer 1

The full exptions are:
Task 205: start
Task 206: start
Task 207: start
        at java.util.ArrayList.RangeCheck(ArrayList.java:547)
        at java.util.ArrayList.get(ArrayList.java:322)
        at edu.stanford.nlp.parser.lexparser.ExhaustivePCFGParser.initializeChart(ExhaustivePCFGParser.java:1236)
        at edu.stanford.nlp.parser.lexparser.ExhaustivePCFGParser.parse(ExhaustivePCFGParser.java:388)
        at edu.stanford.nlp.parser.lexparser.LexicalizedParser.parse(LexicalizedParser.java:372)
Task 208: start
Task 210: start
Task 211: startthe code that have this is
    // Positional Access Operations
     * Returns the element at the specified position in this list.
     * @param  index index of the element to return
     * @return the element at the specified position in this list
     * @throws IndexOutOfBoundsException {@inheritDoc}
    public E get(int index) {
     RangeCheck(index);
     return (E) elementData[index];
    }and
     * Checks if the given index is in range.  If not, throws an appropriate
     * runtime exception.  This method does *not* check if the index is
     * negative: It is always used immediately prior to an array access,
     * which throws an ArrayIndexOutOfBoundsException if index is negative.
    private void RangeCheck(int index) {
     if (index >= size)
         throw new IndexOutOfBoundsException(
          "Index: "+index+", Size: "+size);
    }in this
Tree parse = (Tree) lp.apply(s);
Task 217: start
Task 218: start
        at edu.stanford.nlp.parser.lexparser.LexicalizedParser.apply(LexicalizedParser.java:276)
        at blogsOpinions.ParserText.test(ParserText.java:174)
        at blogsOpinions.ParserText.insertDb(ParserText.java:67)
        at blogsOpinions.ParserText.<init>(ParserText.java:47)
        at blogsOpinions.ThreadPoolTest$1.run(ThreadPoolTest.java:50)
Task 220: start
Task 221: startthe exceptions are full and not cut
thanks