#vulnerable code 
                             public void trainOnSampleDocs() throws Exception {
		documentsPerExemplar = new ArrayList<>();
		featureVectors = new ArrayList<>();
		injectWhitespace = new ArrayList<>();
		hpos = new ArrayList<>();

		for (InputDocument doc : documents) {
			if ( showFileNames ) System.out.println(doc);
			Triple<List<int[]>, List<Integer>, List<Integer>> results = process(doc);
			List<int[]> features = results.a;
			List<Integer> ws = results.b;
			List<Integer> al = results.c;

			for (int i=0; i<features.size(); i++) {
				documentsPerExemplar.add(doc);
				int[] featureVec = features.get(i);
				injectWhitespace.add(ws.get(i));
				hpos.add(al.get(i));
				featureVectors.add(featureVec);
			}
		}
	} 
                            #location 14 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                             public void trainOnSampleDocs() throws Exception {
		documentsPerExemplar = new ArrayList<>();
		featureVectors = new ArrayList<>();
		injectWhitespace = new ArrayList<>();
		hpos = new ArrayList<>();

		for (InputDocument doc : documents) {
			if ( showFileNames ) System.out.println(doc);
			// Parse document, save feature vectors to the doc
			Trainer trainer = new Trainer(this, doc, language.indentSize);
			trainer.computeFeatureVectors();
		}
	}