Java Net Beans menggunakan (METHOD)

package thonbadawi.aji;

import javax.swing.JOptionPane;

public class tokobaju_method extends javax.swing.JFrame {

int merk,harga,beli;

double total,bayar,diskon;

@SuppressWarnings("unchecked")

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

        // TODO add your handling code here:

if (rcelana.isSelected()==true)

    celana();

if (rkemeja.isSelected()==true)

    kemeja();

    }                                     

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

        // TODO add your handling code here:

cmerk.removeAllItems();

cmerk.addItem("- Pilih Merek Celana -");

cmerk.addItem("Carvile");

cmerk.addItem("Lea ");

cmerk.addItem("Marvel");

    }                                       

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

        // TODO add your handling code here:

cmerk.removeAllItems();

cmerk.addItem("- Pilih Merek Celana -");

cmerk.addItem("C59");

cmerk.addItem("Dagadu");

cmerk.addItem("Exlusife");

    }

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

        // TODO add your handling code here:

beli = Integer.parseInt(ebeli.getText());

total = harga*beli;

etotal.setText(String.valueOf(total));

if (total>500000)

    diskon = total*15/100;

else if (total>250000)

        diskon = total*5/100;

else diskon = 0;

ediskon.setText(String.valueOf(diskon));

bayar=total-diskon;

ebayar.setText(String.valueOf(bayar));

    }                                     

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

        // TODO add your handling code here:

group.clearSelection();

cmerk.setSelectedIndex(0);

eharga.setText("0");

ebeli.setText("0");

etotal.setText("0");

ediskon.setText("0");

ebayar.setText("0");

    }                                       

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

        // TODO add your handling code here:

int a= JOptionPane.showConfirmDialog(null,"Ingin Keluar Dari Program","Keterangan"

        ,JOptionPane.YES_NO_OPTION);

if (a==JOptionPane.YES_OPTION)

        System.exit(0);

    else

        return;

    }                                       

void celana()

{

    merk=cmerk.getSelectedIndex();

    switch(merk)

    {

        case 1:

            harga=10000;

            break;

        case 2:

            harga=11000;

            break;

        case 3:

            harga=12000;

            break;

        default:

            harga=0;

            break;

    }

    eharga.setText(String.valueOf(harga));

}

void kemeja()

{

    merk=cmerk.getSelectedIndex();

    switch(merk)

    {

        case 1:

            harga=50000;

            break;

        case 2:

            harga=60000;

            break;

        case 3:

            harga=70000;

            break;

        default:

            harga=0;

            break;

    }

    eharga.setText(String.valueOf(harga));

}