Netbeans : สร้าง Java GUI และการสร้าง Event Action และ Dialog โต้ตอบแบบง่าย ๆ

    private void btnClickActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:

    }    

import javax.swing.JOptionPane;

    private void btnClickActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        JOptionPane.showMessageDialog(this, "Sawatdee : " + txtName.getText());
    }     

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.java.myapp;

import javax.swing.JOptionPane;

/**
 *
 * @author WEERACHAI
 */
public class MyFormApp extends javax.swing.JFrame {

    /**
     * Creates new form MyFormApp
     */
    public MyFormApp() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        txtName = new javax.swing.JTextField();
        btnClick = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        getContentPane().setLayout(null);

        jLabel1.setText("Welcome to ThaiCreate.Com");
        getContentPane().add(jLabel1);
        jLabel1.setBounds(120, 60, 140, 14);

        txtName.setName("txtName"); // NOI18N
        getContentPane().add(txtName);
        txtName.setBounds(70, 100, 260, 20);

        btnClick.setText("Click");
        btnClick.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnClickActionPerformed(evt);
            }
        });
        getContentPane().add(btnClick);
        btnClick.setBounds(150, 140, 90, 23);

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

    private void btnClickActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        JOptionPane.showMessageDialog(this, "Sawatdee : " + txtName.getText());
    }                                        

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        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(MyFormApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MyFormApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MyFormApp.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MyFormApp.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 MyFormApp().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton btnClick;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JTextField txtName;
    // End of variables declaration                   
}

JOptionPane.showMessageDialog(frame,
    "Eggs are not supposed to be green.");

JOptionPane.showMessageDialog(frame,
    "Eggs are not supposed to be green.",
    "Inane warning",
    JOptionPane.WARNING_MESSAGE);

JOptionPane.showMessageDialog(frame,
    "Eggs are not supposed to be green.",
    "Inane error",
    JOptionPane.ERROR_MESSAGE);

JOptionPane.showMessageDialog(frame,
    "Eggs are not supposed to be green.",
    "A plain message",
    JOptionPane.PLAIN_MESSAGE);

JOptionPane.showMessageDialog(frame,
    "Eggs are not supposed to be green.",
    "Inane custom dialog",
    JOptionPane.INFORMATION_MESSAGE,
    icon);