Runtime Exception In Mongo Db Java Query

Question

I am new to java. I am doing a search in window-builder using java-mongodb.

When I execute the below code i get Runtime exception error.

try{   
    // To connect to mongodb server
     MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
      // Now connect to your databases
     DB db = mongoClient.getDB( "Ticket" );
                 System.out.println("Connect to database successfully");
                 DBCollection coll = db.getCollection("OnlineT");
                 System.out.println("Collection created successfully");
                 F_stn = (String)fm.getSelectedItem();
                 T_stn = (String)to.getSelectedItem();
                 BasicDBObject doc = new BasicDBObject("From",F_stn);
                 BasicDBObject doc1 = new BasicDBObject("To",T_stn);
                    DBCursor ser  = coll.find(doc);
                    DBCursor ser2  = coll.find(doc1);


                    while(ser.hasNext())
                    {
                        String data=ser.next().get("To").toString();
                        System.out.println(data);
                        if(data.equals(T_stn))
                        {
                            System.out.println("i m in");

                            String dis=ser.next().toString();

                            System.out.println(dis);
                            break;
                        }
                        else
                            System.out.println("No data found");


                    }
            }

It is working fine but when it enters the if loop it did not print the DBobject.

Please suggest me some way to do this. Thanks in advance..

Answer 1

In the "if" loop, you have: String dis=ser.next().toString();

This makes your cursor move to the next postion and it didn't check hasNext(). I think that is the problem

Instead, you may do something like:

while(ser.hasNext()){
    DBObject dbObject = ser.next();
    String data=dbObject.get("To").toString();
    System.out.println(data);
    if(data.equals(T_stn))
                    {
                        System.out.println("i m in");
                        System.out.println(dbObject);
                        break;
                    }
                    else
                        System.out.println("No data found");

In addition, you don't need toString() for printing, println() will call automatically toString() method of the object