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10/08/2009 at 10:51AM PDT, ID: 24796890
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9.6

Unable to invoke a method on an instance of a class

Asked by aman0711 in Java Programming Language, New to Java Programming, Java Standard Edition

Tags: Java, JDBC

Hi Experts,

          I am stuck with a little silly problem. I have a class for getting connection to
        the database(Code attached)
        now when I am trying to invoke the getConnection of this class on an instance in another
        class where I need the DB connection, its not working.
        what am I doing wrong?

      package com.si.admin;

      import java.sql.*;
      import com.si.admin.*;
      import com.si.dao.DbConn;

      public class TrackingTable
      {
       Connection conn= null;
       DbConn db = new DbConn();
       conn = db.getJNDIConnection();
      }
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package com.si.dao;
 
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
 
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
 
public class DbConn {
 
          /** Uses JNDI and Datasource (preferred style).   */
          static Connection getJNDIConnection(){
            String DATASOURCE_CONTEXT = "java:comp/env/jdbc/t002";
            
            Connection result = null;
            try {
              Context initialContext = new InitialContext();
              if ( initialContext == null){
                log("JNDI problem. Cannot get InitialContext.");
              }
              DataSource datasource = (DataSource)initialContext.lookup(DATASOURCE_CONTEXT);
              if (datasource != null) {
                result = datasource.getConnection();
              }
              else {
                log("Failed to lookup datasource.");
              }
            }
            catch ( NamingException ex ) {
              log("Cannot get connection: " + ex);
            }
            catch(SQLException ex){
              log("Cannot get connection: " + ex);
            }
            return result;
          }
 
          /** Uses DriverManager.  */
          static Connection getSimpleConnection() {
            //See your driver documentation for the proper format of this string :
            String DB_CONN_STRING = "jdbc:oracle:thin:@mtp98.hppwd.xyz.com:1522:t002";
            //Provided by your driver documentation. In this case, a MySql driver is used : 
            String DRIVER_CLASS_NAME = "oracle.jdbc.driver.OracleDriver";
            String USER_NAME = "user1";
            String PASSWORD = "pass1";
            
            Connection result = null;
            try {
               Class.forName(DRIVER_CLASS_NAME).newInstance();
            }
            catch (Exception ex){
               log("Check classpath. Cannot load db driver: " + DRIVER_CLASS_NAME);
            }
 
            try {
              result = DriverManager.getConnection(DB_CONN_STRING, USER_NAME, PASSWORD);
            }
            catch (SQLException e){
               log( "Driver loaded, but cannot connect to db: " + DB_CONN_STRING);
            }
            return result;
          }
 
          private static void log(Object aObject){
            System.out.println(aObject);
          }
        }
[+][-]10/08/09 10:54 AM, ID: 25528109

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About this solution

Zones: Java Programming Language, New to Java Programming, Java Standard Edition
Tags: Java, JDBC
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Solution Provided By: CEHJ
Participating Experts: 3
Solution Grade: A
 
 
[+][-]10/08/09 11:04 AM, ID: 25528243

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[+][-]10/08/09 11:09 AM, ID: 25528301

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[+][-]10/08/09 11:11 AM, ID: 25528329

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