how to access connection object in another class in java?

Question

i am using xampp mysql, this code is for JDBC program. actually there are two class one is dbconnect.java and another is login.java. I want to access the connection object (i.e. conn) in another class(i.e. login.java). But i don't have proper idea, i have included the code here please suggest me what is the problem and what are the solutions?

This is the code of dbconnect.java

package stundentrecord;

import java.sql.Connection;
import java.sql.DriverManager;

public class dbconnect {
    public void conect(){
        Connection con = null;
        String url = "jdbc:mysql://localhost:3306/";
        String db = "studentRecord";
        String driver = "com.mysql.jdbc.Driver";
        String user = "root";
        String pass = "";
        try{
            Class.forName(driver);
            con = DriverManager.getConnection(url + db, user, pass);
            if(con==null){
                System.out.println("Connection cannot be established");
            }
            // con.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

and here is the code from another class named login.java

if(source==login){
    if(username!=null && password!=null) {
        Connection conn= null;
        Statement stmt = null;
        dbconnect db = new dbconnect();
        db.conect();
        String query = "SELECT * from userlogin";
        try{
            stmt=(Statement) conn.createStatement(); // here is the problem
            ResultSet rs = stmt.executeQuery(query);  // here is the problem 
            while (rs.next()) {
                String user = rs.getString("username");
                String pass=rs.getString("password");
                System.out.println("Welcome "+user);
            }
        } catch(SQLException ex){
            ex.getMessage();
        }
        StundentRecord SR = new StundentRecord();
    } else {
        JOptionPane.showMessageDialog(null,"Username or password field is empty","error    !!",JOptionPane.ERROR_MESSAGE);
    }
}

What is the real problem and how to solve it?

Please format your code, this is unreadable. And follow Java conventions (classes are first uppercase, etc...) — m0skit0
– m0skit0, Commented Feb 19, 2013 at 15:00
@SotiriosDelimanolis if you read the code you would understand the design problem — Luiggi Mendoza
– Luiggi Mendoza, Commented Feb 19, 2013 at 15:01
There's a lot to explain, but to start, change your conect function to return the Connection. — Luiggi Mendoza
– Luiggi Mendoza, Commented Feb 19, 2013 at 15:02

Boris the Spider · Accepted Answer · 2013-02-19 15:02:32Z

6

The easiest way would be to make the connect method non void and return the connection:

public Connection conect() {
    Connection con = null;
    String url = "jdbc:mysql://localhost:3306/";
    String db = "studentRecord";
    String driver = "com.mysql.jdbc.Driver";
    String user = "root";
    String pass = "";
    try {
        Class.forName(driver);
        con = DriverManager.getConnection(url + db, user, pass);
        if (con == null) {
            System.out.println("Connection cannot be established");
        }
        return con;
    } catch (Exception e) {
        System.out.println(e);
    }
    return null;
}

answered Feb 19, 2013 at 15:02

Boris the Spider

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Comments

Kanagaraj M · Accepted Answer · 2013-02-19 15:07:11Z

0

You should return your CONNECTION object from you connection class and assign it to your login class... Now your connection object is null...

answered Feb 19, 2013 at 15:07

Kanagaraj M

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