Getting backtype.storm.generated.InvalidTopologyException: null .If I comment call to setBolt it runs

Question

If comment builder.setBolt then it runs correctly.Please tell where I am getting wrong

    TopologyBuilder builder = new TopologyBuilder();
    builder.setSpout("words", new TestWordSpout(), 3);
    //Calling setBolt
    builder.setBolt("exc", new ExclaimBolt(),3)
    .allGrouping("words");

    Config conf = new Config();
    conf.setDebug(false);
    //conf.setNumWorkers(2);

    LocalCluster cluster = new LocalCluster();
    cluster.submitTopology("test", conf, builder.createTopology());

Answer 1

Had not declared output fields in Spout. After declaring it works fine.

code example(in u bolt class):

@Override

public void declareOutputFields(OutputFieldsDeclarer declarer) {

    declarer.declare(new Fields("msg"));//based on u project

}