问Java空指针中的锤子NaiveBayes分类器

EN

public TestMallet() throws IOException {

ArrayList<Pipe> pipelist = new ArrayList<Pipe>();

    pipelist.add (new CharSequenceLowercase() ) ;
    pipelist.add (new CharSequence2TokenSequence(Pattern.compile("\\p{L}[\\p{L}\\p{P}]+\\p{L}")) ) ;

    pipelist.add (new TokenSequenceRemoveStopwords (new File ("c:\\test\\config\\stopwords_en.txt"), "UTF-8", false, false, false) ) ;
    pipelist.add (new TokenSequence2FeatureSequence()) ;
    pipelist.add (new FeatureSequence2FeatureVector()) ; // Added but doesnt make any difference

    InstanceList instances = new InstanceList (new SerialPipes(pipelist)) ;

    Instance instance0 = new Instance("Hello World I am here and i am male my name is roger",   "Male",   "roger", "test") ;
    Instance instance1 = new Instance("Hello World I am here and i am male my name is phil",    "Male",   "phil",  "test") ;
    Instance instance2 = new Instance("Hello World I am here and i am male my name is joe",     "Male",   "joe",   "test") ;
    Instance instance3 = new Instance("Hello World I am here and i am female my name is vira",  "Female", "vira",  "test") ;
    Instance instance4 = new Instance("Hello World I am here and i am female my name is josie", "Female", "josie", "test") ;

    instances.addThruPipe (instance0) ;
    instances.addThruPipe (instance1) ;
    instances.addThruPipe (instance2) ;
    instances.addThruPipe (instance3) ;
    instances.addThruPipe (instance4) ;

    // Using Instance List to train
    // ----------------------------

    ClassifierTrainer trainer = new NaiveBayesTrainer();
    trainer.train(instances); 

// Null pointer exception here ( debugging, it looks like TargetDictionary is null) 

}