Creating Sign up page in Java NetBeans or Eclipse IDE

Imported Libraries are:

import java.sql.Connection;
import javax.swing.JOptionPane;
import java.sql.*;
import java.sql.Statement;
import java.sql.PreparedStatement;

Validating Sign up Forms:

 String fname,lname,uname,password,cpassword,email,contact,account;
    int len , lenno;
    
    boolean validation(){
   fname = txt_firstname.getText();
   lname = txt_lastname.getText();
   uname = txt_username.getText();
   password = txt_password.getText();
   cpassword = txt_confirm_password.getText();
   email = txt_email.getText();
   contact = txt_phoneno.getText();
   account = (String) txt_combo.getSelectedItem();
   len = password.length();
   lenno = contact.length();
   if(fname.equals(""))
   {
       JOptionPane.showMessageDialog(null, "First Name cannot be null");
       return false;
   }
   if(lname.equals(""))
   {
       JOptionPane.showMessageDialog(null, "Last Name cannot be null");
       return false;
   }
   if(uname.equals(""))
   {
       JOptionPane.showMessageDialog(null, "User Name cannot be null");
       return false;
   }
   if(password .equals("") | len < 4)
   {
       JOptionPane.showMessageDialog(null, "Password Enter Correct password");
       return false;
       
   }
   
   if(!cpassword.equals(password)){
       JOptionPane.showMessageDialog(null, "Password cannot be Match");
       return false;
       
       
   }
  
   if(email .equals(""))
   {
       JOptionPane.showMessageDialog(null, "Email cannot be null");
       return false;
   }
   if(contact .equals("") | lenno != 11)
   {
      JOptionPane.showMessageDialog(null, "Please enter correct number");
       return false;
   }
        return true;
    }

Increment id function:

  int id =0;
    public int getid()    
 {
         ResultSet rs = null;
        try{
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/store_managment_system","root","root");
            String query ="select max(id) from signup";
            Statement st = con.createStatement();
            rs = st.executeQuery(query);
             while(rs.next()){
                 
                 id=rs.getInt(1);
                 id++;
             }
        }
        catch(Exception e){
            e.printStackTrace();
        }
        return id;
    }

Insert Values In DataBase :

 void connectdatabase() {
        try{
            //Class.forName("com.mysql.cj.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/store_managment_system","root","root");
            String query ="Insert into signup values(?,?,?,?,?,?,?,?)";
             PreparedStatement pst = con.prepareStatement(query);
             pst.setInt(1, getid());
             pst.setString(2, fname);
             pst.setString(3, lname);
             pst.setString(4, uname);
             pst.setString(5, password );
             pst.setString(6, email);
             pst.setString(7,contact);
             pst.setString(8,account);
             int i = pst.executeUpdate();
             if(i > 0){
                 JOptionPane.showMessageDialog(null,"Account successfully created");
             }
             else
             {
                   JOptionPane.showMessageDialog(null,"Account creation Failed");   
             }
        }
        catch( Exception e){
            e.printStackTrace();
        }
       
    }