Jena's TDB dataset got TDBTransactionException when try to commit an transaction

Question

This is what I wrote:

public static void main(String[] args) {
    Dataset dataset = TDBFactory.createDataset("/tmp/someThings");
    dataset.begin(ReadWrite.WRITE);
    Model model = dataset.getDefaultModel();
    model.setNsPrefix("kg", "http://sankuai.com/kg");
    Resource resource = model.createResource("http://sankuai.com/kg/jena");
    resource.addProperty(model.createProperty("kg", "language"), "SPARQL");
    dataset.commit();
    System.out.println(model);
}

But instead give me some output, It shows an error:

Exception in thread "main" org.apache.jena.tdb.transaction.TDBTransactionException: Not in a transaction

has there something I done was wrong?

Answer 1

The problem is when I retrieve a model:

System.out.println(model);

It must be contained in a transaction, which I am not...