Mahout推荐程序错误：未在第一行找到分隔符

Question

我已经按照本教程进行了操作：

https://ademsha.com/notes/developing-recommendation-system-with-apache-mahout/

它在ml-100k数据集中运行良好，但是当我向u.data文件添加更多评估时（使用完全相同的格式userId, itemId, rating, timestamp），我收到以下错误：

[main] INFO org.apache.mahout.cf.taste.impl.model.file.FileDataModel - Creating FileDataModel for file u.data
Exception in thread "main" java.lang.IllegalArgumentException: Did not find a delimiter in first line
at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.determineDelimiter(FileDataModel.java:351)
at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>(FileDataModel.java:201)
at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>(FileDataModel.java:169)
at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<init>(FileDataModel.java:149)
at teste.HelloMaven.SimpleRec.main(SimpleRec.java:20)

代码是这样的：

public class SimpleRec {

    public static void main(String[] args) throws Exception {

        DataModel model = new FileDataModel(new File("u.data"));

        UserSimilarity similarity = new PearsonCorrelationSimilarity(model);

        UserNeighborhood neighborhood = new ThresholdUserNeighborhood(0.5, similarity, model);

        Recommender recommender = new GenericUserBasedRecommender(model,neighborhood, similarity);

        List<RecommendedItem> recomendations = recommender.recommend(943,5);

        for (RecommendedItem recomendation : recomendations) {
            System.out.println(recomendation);
        }
    }
}