Sample Java code for putting some data in a MongoDB collection. Then querying the collection, iterating over the results and extracting fields.

CursorIteration.java

import java.net.UnknownHostException;

import com.mongodb.*;

public class CursorIteration
{
    public static void main(String[] args) throws UnknownHostException, MongoException
    {
        Mongo mongo = new Mongo();
        DB db = mongo.getDB("play");
        DBCollection students = db.getCollection("students");
        
        populateStudents(students);
        
        queryAndDisplayStudents(students);
    }

    private static void populateStudents(DBCollection students)
    {
        BasicDBObject student1 = new BasicDBObject();
        student1.put("Name", "Bob Smythe");
        student1.put("SID", 1234);
        student1.put("University", "Harvard");
        students.insert(student1);

        BasicDBObject student2 = new BasicDBObject();
        student2.put("Name", "Mary Brown");
        student2.put("SID", 5678);
        student2.put("University", "Yale");
        students.insert(student2);

        BasicDBObject student3 = new BasicDBObject();
        student3.put("Name", "Mike Black");
        student3.put("SID", 9876);
        student3.put("University", "Princeton");
        students.insert(student3);
    }
    
    private static void queryAndDisplayStudents(DBCollection students)
    {
        // Get all students (no query criteria).
        DBCursor cursor = students.find();
        
        // Iterate over the students.
        while (cursor.hasNext()) 
        {
            // Display each student.

            DBObject student = cursor.next();
            
            // Get the individual fields of the student document.
            // These individual fields could, for example, be put in text fields of a GUI.
            String name = (String) student.get("Name");
            Number sid  = (Number) student.get("SID");
            String university = (String) student.get("University");
            
            // Given that we are not actually building a GUI, just display the fields on the command line.
            System.out.printf("Student name: %s, SID: %d, University: %s%n", name, sid, university);
        }        
    }
}