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POWhy is rs.next() not working properly?
 

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  1. POWhy is rs.next() not working properly?
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    <p>EDIT: SOLVED! Thanks guys! :D</p> <p>Even if I type with the right credentials I still get the error showMessageDialog.. I believe that rs.next() will return a value higher than 0 then it has to confim if the user's credentials will match with the ones in the users_table but I'm always getting the error message as if the credentials were mismatched.</p> <pre><code>import java.sql.*; import javax.swing.*; public class System extends javax.swing.JFrame { // variables needed for db connection Connection conn; Statement stmt; ResultSet rs; String sql; String user; char[] pass; //for table row count int ctr = 0; //temporary variables needed in retrieving and inserting records in our db int user_id; String username; String password; public System() { initComponents(); setLocationRelativeTo(null); dbConnect(); } public void dbConnect() { conn = null; String url = "jdbc:mysql://localhost:3306/item_db"; String driver = "com.mysql.jdbc.Driver"; String userName = "root"; String password = ""; try { Class.forName(driver).newInstance(); conn = DriverManager.getConnection(url, userName, password); stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); sql = "Select * from users_table"; rs = stmt.executeQuery(sql);//rs - will hold the records from the databa sql = "Select * from item_table";se } catch (Exception e) { JOptionPane.showMessageDialog(this, e.getMessage()); } } private void login() { try { if (user != null &amp;&amp; pass != null) { sql = "Select * from users_table Where username='" + user + "' and password='" + pass + "'"; rs = stmt.executeQuery(sql); rs.next(); if ((user.equals(username)) &amp;&amp; (pass.equals(password))) { JOptionPane.showMessageDialog(null, "You are now logon!"); } else { JOptionPane.showMessageDialog(null, "damn!", "alert", JOptionPane.ERROR_MESSAGE); } } } catch (SQLException err) { JOptionPane.showMessageDialog(this, err.getMessage()); } } @SuppressWarnings("unchecked") // &lt;editor-fold defaultstate="collapsed" desc="Generated Code"&gt; private void initComponents() { jLabel1 = new javax.swing.JLabel(); jLabel2 = new javax.swing.JLabel(); jTextField1 = new javax.swing.JTextField(); jButton1 = new javax.swing.JButton(); jButton2 = new javax.swing.JButton(); jPasswordField1 = new javax.swing.JPasswordField(); jLabel3 = new javax.swing.JLabel(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); jLabel1.setFont(new java.awt.Font("Calibri", 0, 18)); // NOI18N jLabel1.setText("Username:"); jLabel2.setFont(new java.awt.Font("Calibri", 0, 18)); // NOI18N jLabel2.setText("Password:"); jButton1.setText("Login"); jButton1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jButton1ActionPerformed(evt); } }); jButton2.setText("Cancel"); jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/login.png"))); // NOI18N javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(46, 46, 46) .addComponent(jLabel3)) .addGroup(layout.createSequentialGroup() .addGap(82, 82, 82) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING) .addComponent(jLabel2) .addComponent(jLabel1)) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false) .addComponent(jTextField1) .addComponent(jPasswordField1, javax.swing.GroupLayout.PREFERRED_SIZE, 134, javax.swing.GroupLayout.PREFERRED_SIZE))) .addGroup(layout.createSequentialGroup() .addGap(51, 51, 51) .addComponent(jButton1) .addGap(28, 28, 28) .addComponent(jButton2))))) .addContainerGap(52, Short.MAX_VALUE)) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup() .addComponent(jLabel3, javax.swing.GroupLayout.DEFAULT_SIZE, 100, Short.MAX_VALUE) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(jLabel1) .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(jLabel2) .addComponent(jPasswordField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) .addGap(18, 18, 18) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(jButton1) .addComponent(jButton2)) .addGap(29, 29, 29)) ); pack(); }// &lt;/editor-fold&gt; private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { // TODO add your handling code here: //str = JOptionPane.showInputDialog(this, "Enter id number: "); user = jTextField1.getText(); pass = jPasswordField1.getPassword(); login(); } /** * @param args the command line arguments */ public static void main(String args[]) { /* Set the Nimbus look and feel */ //&lt;editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) "&gt; /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel. * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html */ try { for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) { if ("Nimbus".equals(info.getName())) { javax.swing.UIManager.setLookAndFeel(info.getClassName()); break; } } } catch (ClassNotFoundException ex) { java.util.logging.Logger.getLogger(System.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (InstantiationException ex) { java.util.logging.Logger.getLogger(System.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (IllegalAccessException ex) { java.util.logging.Logger.getLogger(System.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (javax.swing.UnsupportedLookAndFeelException ex) { java.util.logging.Logger.getLogger(System.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } //&lt;/editor-fold&gt; /* Create and display the form */ java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new System().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JButton jButton1; private javax.swing.JButton jButton2; private javax.swing.JLabel jLabel1; private javax.swing.JLabel jLabel2; private javax.swing.JLabel jLabel3; private javax.swing.JPasswordField jPasswordField1; private javax.swing.JTextField jTextField1; // End of variables declaration } </code></pre>
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    1. COWhich of the dialogs is shown? If it is the one in the catch, which is the message?
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      1. USSJuan76
    2. COyou call `rs.next()` without checking the value at all! Also, you should use `PreparedStatement` or prepare yourself to meet [Little Bobby Tables](http://xkcd.com/327/).
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      1. USjlordo
    3. COYou've provided nearly *200* lines of code, the vast majority of which are going to be irrelevant. If you'd cut this down to a short but complete console application demonstrating the problem (and *only* the problem) I suspect it could be about 30 lines, if that.
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      1. USJon Skeet
 

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