MongoDB with Java, cannot get Collection

Question

I am starting a project with MongoDB. I have my DB :

mongo=null;
    try {
        mongo = new Mongo();
    } catch (UnknownHostException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (MongoException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    db = mongo.getDB( "mydb" );
    System.out.print(db.getName());//just a test

And I want to show all the elements of a particular collection (in a scrollPane, but that isn't important to the question). The collection doesn't exist initially, because the database, "mydb" is empty. This is my code:

        DBCursor cur = db.getCollection("newcollection").find();//collection should be created at this point, if it doesnt exist.


        while(cur.hasNext()) { //<----exception caused here
            //do something with cursor...
        }

Even though initially the collection is empty, on further use of the application elements will be added, so I need to search through it from when the application is started to fill in my scrollPane.

This is the stacktrace:

        java.io.IOException: couldn't connect to [/127.0.0.1:27017] bc:java.net.ConnectException:     Connection refused: connect
at com.mongodb.DBPort._open(DBPort.java:222)
    at com.mongodb.DBPort.go(DBPort.java:111)
at com.mongodb.DBPort.call(DBPort.java:78)
at com.mongodb.DBTCPConnector.call(DBTCPConnector.java:217)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:313)
at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:298)
at com.mongodb.DBCursor._check(DBCursor.java:369)
at com.mongodb.DBCursor._hasNext(DBCursor.java:492)
at com.mongodb.DBCursor.hasNext(DBCursor.java:517)
at MainFrame$MyPanel.<init>(MainFrame.java:120)//<----cur.hasNext()

Any ideas what I'm doing wrong?

Jan Zyka · Accepted Answer · 2012-06-21 16:54:18Z

2

My feeling here is that you DB is not running at all. Could you try to connect to the DB from command line using "mongo" and validate it is up and running?

answered Jun 21, 2012 at 16:54

Jan Zyka

18k18 gold badges75 silver badges120 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Julias · Accepted Answer · 2012-06-21 16:56:19Z

0

You can check before the printing if the collection exists

db.collectionExists("coll_name")

In case if not you can create it, or maybe ensure some index - It will create it automatically I'm usually doing such operation on spring startup ( for example @PostConstruct )

edited Jun 21, 2012 at 16:56

answered Jun 21, 2012 at 16:49

Julias

5,91219 gold badges63 silver badges89 bronze badges

Collectives™ on Stack Overflow

MongoDB with Java, cannot get Collection

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related