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JavaRanch » Java Forums » Databases » JDBC and Relational Databases
Bookmark "JDBC problems" Watch "JDBC problems" New topic

JDBC problems

Prabhudatta Choudhury

Joined: Jul 03, 2009
Posts: 20


I am facing a problem in simple JDBC. I have one class where I have declared a String variable to collect some data form DB(Oracle 9i). I want to reuse those data out side of the method but inside of the same class. But its returning null. please verify the code and let me know where I can improve.


public class Test{

public Vector ogetData(){

Connection loConnection = null;
Statement loStmt = null;
ResultSet loRS = null;
loConnection = ogetConnection(CTPUIConstants.CONNECTION_POOL_NAME); // I am collecting this connection object from a connection pool.I am damn sure those codes are find with no error and exception.

String message = "";
StringBuffer loQuery = new StringBuffer();

loStmt = loConnection.createStatement();
loRS = loStmt.executeQuery(loQuery.toString());

Vector loCVector = loRS.getString(1);
Vector loMVector = loRS.getString(2);
boolean lbITP = loRS.getString(3);
boolean lbILP = loRS.getString(4);

message = loCVector .toString()+loMVector .toString()+lbITP .toString()+lbILP .toString();

catch (Exception e){e.printStackTrace();}


return loCVector ;
return loMVector ;

public void printMessge(){

System.out.println("The message from DB is :" +message);


public inti(){

Test t1 = new Test();



When I tried to print the value of that String "message" its getting blank. I want those values to be append in that. please suggest.

John Jai

Joined: May 31, 2011
Posts: 1776
The String variable message is declared as a local variable in the ogetData() method. To access the message variable outside the ogetData() method, in other methods of the class, then the String variable should be a class variable. Make sure to remove the declaration of the message local variable - since a local variable masks the class variable, the instance variable you newly declared will not be assigned a value in the below line -

See below code on further explanation for local & instance variable sample - uncomment the message variable declaration and run again.

Also please use code tags when you post the code. Its not using <code> </code> but [code] and corresponding closure... UseCodeTags
Sherif Shehab
Ranch Hand

Joined: Mar 05, 2007
Posts: 483

I cant see in your code any declarations for Vectors loCVector , loMVector

Campbell Ritchie

Joined: Oct 13, 2005
Posts: 44616
Moving to our databases forum.
Jeanne Boyarsky
author & internet detective

Joined: May 26, 2003
Posts: 32649

raghav sai,
Your post was moved to a new topic.
Starting a new thread for a new topic

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