Asgn_12.java

import com.mongodb.*;
import java.util.Scanner;

 public class Asgn_12 {
     private static void choice_input() {
         System.out.println("\n1. Insert data into the database\n2. Update database documents\n3. Delete database documents\n4. Show database collections\n5. Exit");
     }

     public static void main(String[] args) {
         String key, value;
         Scanner scanner = new Scanner(System.in);
         int choice;
         try {
        	   MongoClient mongoClient = new MongoClient("10.10.10.176", 27017);
             DB db = mongoClient.getDB("31253_db");
             DBCollection collection = db.getCollection("Students");

             do {
                 choice_input();
                 System.out.println("Enter your choice: ");
                 choice = scanner.nextInt();

                 switch (choice) {
                     case 1:
                         BasicDBObject document = new BasicDBObject();
                         String ch;
                         do {
                             System.out.println("Enter key: ");
                             key = scanner.next();
                             System.out.println("Enter value: ");
                             value = scanner.next();
                             document.put(key, value);
                             System.out.println("Do you want to enter more (y/n)? ");
                             ch = scanner.next();
                         } while (!ch.equals("n"));
                         collection.insert(document);
                         break;
                     case 2:
                         BasicDBObject searchObj = new BasicDBObject();
                         System.out.println("Enter searched key: ");
                         key = scanner.next();
                         System.out.println("Enter searched value: ");
                         value = scanner.next();
                         searchObj.put(key, value);

                         BasicDBObject newObj = new BasicDBObject();
                         System.out.println("Enter new key: ");
                         key = scanner.next();
                         System.out.println("Enter new value: ");
                         value = scanner.next();
                         newObj.put(key, value);

                         BasicDBObject updateQuery = new BasicDBObject("$set", newObj);
                         collection.update(searchObj, updateQuery);
                         break;
                     case 3:
                         System.out.println("Enter removable key: ");
                         key = scanner.next();
                         System.out.println("Enter removable value: ");
                         value = scanner.next();
                         BasicDBObject removableObj = new BasicDBObject(key, value);
                         collection.remove(removableObj);
                         break;
                     case 4:
                         DBCursor cursorDoc = collection.find();
                         while (cursorDoc.hasNext()) {
                             System.out.println(cursorDoc.next());
                         }
                         break;
                     case 5:
                    	 mongoClient.close();
                    	 scanner.close();
                         System.exit(0);
                         break;
                 }
             } while (choice != 5);
         } catch (MongoException e) {
             e.printStackTrace();
         }
     }
 }