java gui เก็บค่าไว้ใน Class แล้วส่งค่าข้ามฟอร์มยังไง เคยอ่านในกระทู้แล้วแต่ก็ไม่เข้าใจ

public class MainLogin extends javax.swing.JFrame { 
    public MainLogin() {
        initComponents();
    }
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test1","root","1234"); 
        String sql = " SELECT * FROM  account  WHERE Acc = ?  AND Pin = ? ";
        PreparedStatement pst = con.prepareStatement(sql);
        pst = con.prepareStatement(sql);
        pst.setString(1, jTextField1.getText());
        pst.setString(2, jTextField2.getText());
        ResultSet rs = pst.executeQuery();
        rs = pst.executeQuery();
        if(rs.next()){
            MainMenu menu = new MainMenu();
            menu.setVisible(true);
            setVisible(false);
            
        }
        else{
            JOptionPane.showMessageDialog(null,"เลขบัญชีหรือรหัสผ่านผิดพลาด");
            jTextField1.setText("");
            jTextField2.setText("");
        }
        con.close();
    }
    catch(Exception e){
        JOptionPane.showMessageDialog(null,e);
    }
    }

public class MainLogin extends javax.swing.JFrame { 
    public MainLogin() {
        initComponents();
    }                  

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

    try{
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test1","root","1234"); 
        String sql = " SELECT * FROM  account  WHERE Acc = ?  AND Pin = ? ";
        PreparedStatement pst = con.prepareStatement(sql);
        pst = con.prepareStatement(sql);
        pst.setString(1, jTextField1.getText());
        pst.setString(2, jTextField2.getText());
        ResultSet rs = pst.executeQuery();
        rs = pst.executeQuery();
        if(rs.next()){
            MainMenu menu = new MainMenu();
            menu.setVisible(true);
            setVisible(false);
            
            Variable user = new Variable();
            user.settest1(rs.getString("Acc"));
        }
        else{
            JOptionPane.showMessageDialog(null,"เลขบัญชีหรือรหัสผ่านผิดพลาด");
            jTextField1.setText("");
            jTextField2.setText("");
        }
        con.close();
    }
    catch(Exception e){
        JOptionPane.showMessageDialog(null,e);
    }
    }  

public class Withdraw extends javax.swing.JFrame {
Connection conn;  // Connection to DB
ResultSet rs;   // Resultset for Push 
PreparedStatement pst;  // Set  

   
    public Withdraw() {
        super("withdrwal");
        initComponents();
        conn =Connect.ConnecrDB();
        jButton1.setEnabled(false);
        jButton2.setEnabled(false);
        jButton3.setEnabled(false);
        
    }
                        
    private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // exit Button
        JOptionPane.showMessageDialog(null,"กลับหน้าเมนู");        
         new MainMenu().setVisible(true); 
         this.setVisible(false);
    }                                        

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
         // Withdraw Button
        try{
            if (jTextField7.getText()!="ไม่สามารถถอนเงินได้"){
               String v1=jTextField1.getText();
               String v2=jTextField7.getText();
            // String value3=jTextField3.getText();
               String sql="update Account set Balance ='"+ v2 +"'where Acc='"+ v1 +"'";
               pst=conn.prepareStatement(sql);
               pst.execute();                
               JOptionPane.showMessageDialog(null,"จำนวนเงินถูกถอนแล้ว!");
            }
            jTextField1.setText(""); 
            jTextField2.setText("");
            jTextField3.setText("");
            jTextField4.setText("");
            jTextField5.setText("");
            jTextField6.setText("");
            jTextField7.setText("");
        } catch (Exception e){
            JOptionPane.showMessageDialog(null,e);
        }
        try{
            rs.close();
            pst.close();

        }catch(Exception e){   // fetcher for basura codes and exception for java
        }
    }                                        

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // View Button
        // Compute Button
        try{
            if (Integer.valueOf(jTextField6.getText())<100){
            jTextField7.setText("ไม่สามารถถอนเงินได้");
            JOptionPane.showMessageDialog(null, "ไม่สามารถถอนเงินได้ ยอดเงินต่ำกว่า 100 บาท");
           }else{
            //String v1=jTextField5.getText();
            //String v2=jTextField6.getText();
            //int sub = Integer.parseInt(v2)- Integer.parseInt(v1);
            //int sub = (Integer.parseInt(v2))- (Integer.parseInt(v1));    
                int sub = Integer.valueOf(jTextField5.getText()) - Integer.valueOf(jTextField6.getText());
                if (sub<0){
                    jTextField7.setText("ไม่สามารถถอนเงินได้");
                   JOptionPane.showMessageDialog(null, "ไม่สามารถถอนเงินได้");
                 }else{
                    String sub1 = String.valueOf(sub);                                                        
                    jTextField7.setText(sub1);
                 }
            }
        }catch(Exception e){
            JOptionPane.showMessageDialog(null, e);
        }
    }                                        

    private void jButton2MouseReleased(java.awt.event.MouseEvent evt) {                                       
        // TODO add your handling code here:
        jButton1.setEnabled(false);
        jButton2.setEnabled(true);
        jButton3.setEnabled(true);
    }                                      

    private void jTextField6KeyTyped(java.awt.event.KeyEvent evt) {                                     
        // event that will only accept Numbers
        char a=evt.getKeyChar();
        if(!(Character.isDigit(a) || (a==KeyEvent.VK_BACK_SPACE) || a==KeyEvent.VK_DELETE)){
            getToolkit().beep();
            evt.consume();
        }
    }                                    

    private void jTextField6KeyReleased(java.awt.event.KeyEvent evt) {                                        
        // enable view button

        jButton1.setEnabled(false);
        jButton2.setEnabled(true);
        jButton3.setEnabled(false);
    }                                       

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // Check Button for Balance Inquiry
        String sql="select * from Account where Acc=?";
        try{
            pst=conn.prepareStatement(sql);
            pst.setString(1, jTextField1.getText());
            rs=pst.executeQuery();
            if(rs.next()){
                String add1=rs.getString("Name"); // this is name of the DB Variable
                jTextField2.setText(add1);

                String add2=rs.getString("Cardno"); // this is name of the DB Variable
                jTextField3.setText(add2);

                String add3=rs.getString("Ctype"); // this is name of the DB Variable
                jTextField4.setText(add3);

                String add4=rs.getString("Balance"); // this is name of the DB Variable
                jTextField5.setText(add4);
            }

            rs.close();
            pst.close();

        }catch (Exception e){
            JOptionPane.showMessageDialog(null,e);
        }

    }                                        

    private void jButton1MouseClicked(java.awt.event.MouseEvent evt) {                                      
        // enable when mouse click
        jButton1.setEnabled(false);
        jButton2.setEnabled(false);
        jButton3.setEnabled(false);
    }                                     

    private void jTextField1KeyTyped(java.awt.event.KeyEvent evt) {                                     
        // event that will only accept Numbers

        char a=evt.getKeyChar();
        if(!(Character.isDigit(a) || (a==KeyEvent.VK_BACK_SPACE) || a==KeyEvent.VK_DELETE)){
            getToolkit().beep();
            evt.consume();

        }
    }                                    

    private void jTextField1KeyPressed(java.awt.event.KeyEvent evt) {                                       
        // activate button when characters are present
        jButton1.setEnabled(true);
        jButton2.setEnabled(false);
        jButton3.setEnabled(false);
    }                                      

    private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // Clear Button for change pin
        jTextField1.setText("");
        jTextField2.setText("");
        jTextField3.setText("");
        jTextField4.setText("");
        jTextField5.setText("");
        jTextField6.setText("");
        jTextField7.setText("");
    }