FORM: SIMPLE CALCULATION

import javax.swing.JOptionPane;

public class konversiBagi extends javax.swing.JFrame {

    public konversiBagi() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        lblNumber1 = new javax.swing.JLabel();
        satu = new javax.swing.JTextField();
        lblNumber2 = new javax.swing.JLabel();
        dua = new javax.swing.JTextField();
        bagi = new javax.swing.JButton();
        hasilnya = new javax.swing.JTextField();
        lblNumber3 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        lblNumber1.setText("number  1");
        lblNumber2.setText("number  2");
        bagi.setText("hasil bagi");

        bagi.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {
                bagiActionPerformed(evt);
            }
        });

        hasilnya.setText("hasil");
        lblNumber3.setText("hasil");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(49, 49, 49)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(lblNumber2)
                    .addComponent(lblNumber1)
                    .addComponent(lblNumber3))
                .addGap(84, 111, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(bagi)
                    .addComponent(satu, javax.swing.GroupLayout.PREFERRED_SIZE, 135, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(dua, javax.swing.GroupLayout.PREFERRED_SIZE, 135, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(hasilnya, javax.swing.GroupLayout.PREFERRED_SIZE, 134, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(78, 78, 78))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(47, 47, 47)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(lblNumber1)
                    .addComponent(satu, 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(lblNumber2)
                    .addComponent(dua, 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(hasilnya, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(lblNumber3))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(bagi)
                .addContainerGap(29, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>

    private void bagiActionPerformed(java.awt.event.ActionEvent evt) {
        float num1;
        float num2;

        if (dua.getText().isEmpty() || satu.getText().isEmpty()) {
            JOptionPane.showMessageDialog(this, "Isi semua!", "Pesan", javax.swing.JOptionPane.INFORMATION_MESSAGE);
        } else {
            num1 = Float.parseFloat(satu.getText());
            num2 = Float.parseFloat(dua.getText());

            if (num2 == 0 || num1 == 0) {
                dua.setText("");
                dua.requestFocus();
                satu.setText("");
                satu.requestFocus();
                JOptionPane.showMessageDialog(this, "Angka dilarang 0 (nol)", "Pesan", javax.swing.JOptionPane.INFORMATION_MESSAGE);
            }  else {
                float hasil = num1 / num2;
                hasilnya.setText(String.valueOf(hasil));
                JOptionPane.showMessageDialog(this, "Hasil bagi: " + hasilnya.getText(), "Pembagian", JOptionPane.INFORMATION_MESSAGE);
            }
        }
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {

        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(konversiBagi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(konversiBagi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(konversiBagi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(konversiBagi.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new konversiBagi().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton bagi;
    private javax.swing.JTextField dua;
    private javax.swing.JTextField hasilnya;
    private javax.swing.JLabel lblNumber1;
    private javax.swing.JLabel lblNumber2;
    private javax.swing.JLabel lblNumber3;
    private javax.swing.JTextField satu;
    // End of variables declaration
}