I wanted to created a simple login form for a system I am tasked to do, however when I click the button (even without any data in the textfields) it would say "Java.lang.NullPointerException". I already tried checking my code but I am still clueless as to which is causing the problem. Here is my JFrame Login Form:
package login;
import java.sql.*;
import javax.swing.*;
public class LOGINN extends javax.swing.JFrame {
PreparedStatement pst = null;
ResultSet rs = null;
MySqlConnect m2 = new MySqlConnect();
/** Creates new form LOGINN */
public LOGINN() {
initComponents();
}
@SuppressWarnings("unchecked")
private void btnloginActionPerformed(java.awt.event.ActionEvent evt) {
Connection con = m2.getConnectDB();
String SQL="Select * from login where username=? and password=?";
try{
rs=pst.executeQuery(SQL);
pst.setString(1,txtusername.getText());
pst.setString(2, txtpassword.getText());
rs=pst.executeQuery();
if(rs.next()){
JOptionPane.showMessageDialog(null, "Welcome!");
ADMIN a=new ADMIN();
a.setVisible(true);
}
else{
JOptionPane.showMessageDialog(null, "Invalid Username or Password", "Access Denied",JOptionPane.ERROR_MESSAGE);
}
}
catch(Exception e){
JOptionPane.showMessageDialog(null, e);
}
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new LOGINN().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btnlogin;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JPanel jPanel1;
private javax.swing.JPasswordField txtpassword;
private javax.swing.JTextField txtusername;
// End of variables declaration
}
Here is MySqlConnect class:
package login;
import com.mysql.jdbc.Connection;
import java.sql.DriverManager;
public class MySqlConnect {
public Connection getConnectDB()
{
Connection con ;
try{
Class.forName("com.mysql.jdbc.Driver");
con = (Connection) DriverManager.getConnection("jdbc:mysql:///login", "root","");
return con;
}
catch (Exception e){
e.printStackTrace();
return null;
}
}
}
PS. I also have a Jframe form named ADMIN and I have data in my PhpMyAdmin SQL Database.
