contoh program Java

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

import java.math.BigDecimal;
import java.math.RoundingMode;
/**
 *
 * @author echo
 */
public class CelciusConverterGUI extends javax.swing.JFrame {
     private double b;
     private int a;
     private String teks;
   
   
    /**
     * Creates new form CelciusConverterGUI
     */
    public CelciusConverterGUI() {
        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() {

        buttonGroup1 = new javax.swing.ButtonGroup();
        tempTextField = new javax.swing.JTextField();
        convertButton = new javax.swing.JButton();
        hasilLabel = new javax.swing.JLabel();
        kelvinButton = new javax.swing.JRadioButton();
        reamurButton = new javax.swing.JRadioButton();
        fahrenheitButton = new javax.swing.JRadioButton();
        jLabel1 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Celcius Converter");

        tempTextField.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                tempTextFieldActionPerformed(evt);
            }
        });

        convertButton.setText("Convert");
        convertButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                convertButtonActionPerformed(evt);
            }
        });

        buttonGroup1.add(kelvinButton);
        kelvinButton.setSelected(true);
        kelvinButton.setText("kelvin");

        buttonGroup1.add(reamurButton);
        reamurButton.setText("reamur");

        buttonGroup1.add(fahrenheitButton);
        fahrenheitButton.setText("fahrenheit");

        jLabel1.setText("Celcius");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(26, 26, 26)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(kelvinButton)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(reamurButton)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(fahrenheitButton))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(convertButton)
                            .addComponent(tempTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(hasilLabel))
                            .addGroup(layout.createSequentialGroup()
                                .addGap(4, 4, 4)
                                .addComponent(jLabel1)))))
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
        );

        layout.linkSize(javax.swing.SwingConstants.HORIZONTAL, new java.awt.Component[] {convertButton, tempTextField});

        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(tempTextField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jLabel1))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 8, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(kelvinButton)
                    .addComponent(reamurButton)
                    .addComponent(fahrenheitButton))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(convertButton)
                    .addComponent(hasilLabel))
                .addGap(18, 18, 18))
        );

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

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

    private void convertButtonActionPerformed(java.awt.event.ActionEvent evt) {                                            
        // TODO add your handling code here:
        a= Integer.parseInt(tempTextField.getText());
       
        if (kelvinButton.isSelected()){
           b=273.15+a;  
           teks="Kelvin";
        }
        else if(reamurButton.isSelected()){
            b=a*0.8;
            teks="Reamur";
        }
        else{
            b= ((1.8*a)+32);
            teks="Fahrenheit";
        }
             
        BigDecimal komaTerbatas1 = new BigDecimal(b).setScale(1, RoundingMode.UP);
        hasilLabel.setText(komaTerbatas1 +" "+teks);
    }                                            

    /**
     * @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(CelciusConverterGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(CelciusConverterGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(CelciusConverterGUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(CelciusConverterGUI.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 CelciusConverterGUI().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                    
    private javax.swing.ButtonGroup buttonGroup1;
    private javax.swing.JButton convertButton;
    private javax.swing.JRadioButton fahrenheitButton;
    private javax.swing.JLabel hasilLabel;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JRadioButton kelvinButton;
    private javax.swing.JRadioButton reamurButton;
    private javax.swing.JTextField tempTextField;
    // End of variables declaration                  
}