Archive for the ‘Java’ Category
POLIMORFISME
Polymorphism atau Polimorfisme – dari namanya dapat diartikan : poli = banyak, morph=bentuk. Yup, memang arti polimorfisme pada Java mendekati hal itu, tepatnya satu metode yang mempunyai banyak bentuk, tergantung Objek yang dimasukkan dalam parameter. Ini contohnya: Misal, pertama saya punya kelas bernama Mobil, seperti di bawah ini:
package polymorph;
public class Mobil
{
String merk()
{
return "Mobil tanpa merk";
}
}
Saya juga punya kelas Suzuki dan Toyota yang diextends dari kelas Mobil:
package polymorph;
public class Suzuki extends Mobil
{
@Override
String merk()
{
return "Saya naik mobil Suzuki";
}
}
package polymorph;
public class Toyota extends Mobil
{
@Override
String merk()
{
return "Saya naik mobil Toyota";
}
}
Lalu saya punya kelas Pengendara yang ceritanya akan naik mobil:
package polymorph;
public class Pengendara
{
private Mobil mobil=new Mobil();
public void merkMobil()
{
System.out.println(mobil.merk());
}
public void setMobil(Mobil b)
{
this.mobil=b;
}
public Mobil getMobil()
{
return mobil;
}
}
Terakhir, saya punya kelas Tester yang akan mengimplementasikan polimorfisme :
package polymorph;
public class Tester
{
public static void main(String[] args)
{
Pengendara budi=new Pengendara();
Suzuki suzuki = new Suzuki();
Toyota toyota = new Toyota();
budi.setMobil(suzuki); //menyuruh budi naik mobil
budi.merkMobil(); //menyuruh budi menyebut merk mobil
}
}
Pada contoh kelas Tester di atas, saya suruh si budi naik mobil suzuki. Setelah itu budi saya suruh sebut merknya. Output dari kelas Tester di atas adalah Saya naik mobil Suzuki. Tetapi jika saya ubah statement
budi.setMobil(suzuki);
menjadi
budi.setMobil(toyota);
maka hasil outputnya adalah Saya naik mobil Toyota. Jadi dapat dilihat sendiri bahwa Anda hanya menjalankan satu buah method saja yaitu
budi.merkMobil();
tetapi dapat menghasilkan sesuatu yang berbeda tergantung objek yang diberikan. Itulah polimorfisme. Oke.. Semoga artikel ini membantu Anda dalam memahami polimorfisme.
MEMBUAT SHUTDOWN TIMER DENGAN MEMANFAATKAN PROGRAM SHUTDOWN.EXE WINDOWS
Pada Windows XP, terdapat aplikasi bawaan untuk shutdown Windows itu sendiri yaitu shutdown.exe yang terletak di C:\WINDOWS\system32. Sebetulnya aplikasi shutdown bawaan Windows ini dapat dijalankan dengan menggunakan command prompt. Tetapi biasanya orang menjalankan dengan menjalankan menu start –> Turn Off Computer… –> shutdown. Dan hasilnya, komputer pasti langsung mati. Kita tidak dapat mengeset parameter yang ada pada shutdown.exe. Nah, bagaimana caranya jika mau mematikan komputer 1 jam lagi misalnya? Kita dapat menjalankan command prompt lalu mengetikkan shutdown -s -t 3600. -s artinya shutdown sedangkan -t 3600 berarti mengeset waktu 1 jam sebelum komputer mati. Cara ini dapat dilakukan tetapi mungkin tidak nyaman bagi sebagian orang. Untuk itu saya mencoba membuat aplikasi untuk menjalankan shutdown.exe milik Windows XP dengan Java. Berikut ini sorce codenya :
/*
* Main.java
*
* Created on June 4, 2008, 6:47 AM
*/
package shutdowntimer;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
/**
*
* @author FX. Budi Ariyanto
*/
public class Main extends javax.swing.JFrame {
/** Creates new form Main */
public Main() throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
initComponents();
}
private ProcessBuilder pb=null;
private Integer hour=1,minute=0,second=0,timer=3600;
/** 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() {
jPanel1 = new javax.swing.JPanel();
jLabel1 = new javax.swing.JLabel();
jLabel2 = new javax.swing.JLabel();
btnGo = new javax.swing.JButton();
btnCancel = new javax.swing.JButton();
spnHour = new javax.swing.JSpinner();
spnMinute = new javax.swing.JSpinner();
spnSeconds = new javax.swing.JSpinner();
cmbAction = new javax.swing.JComboBox();
jLabel3 = new javax.swing.JLabel();
jLabel4 = new javax.swing.JLabel();
jLabel5 = new javax.swing.JLabel();
jMenuBar1 = new javax.swing.JMenuBar();
menuFile = new javax.swing.JMenu();
itemExit = new javax.swing.JMenuItem();
menuAbout = new javax.swing.JMenu();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("ShutdownTimer 1.0");
jLabel1.setText("Set Timer :");
jLabel2.setText("Action :");
btnGo.setText("Go!");
btnGo.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnGoActionPerformed(evt);
}
});
btnCancel.setText("Cancel Action");
btnCancel.setEnabled(false);
btnCancel.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
btnCancelActionPerformed(evt);
}
});
spnHour.setValue(1);
cmbAction.setMaximumRowCount(4);
cmbAction.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Shutdown", "Restart", "Log Off" }));
jLabel3.setText("hour(s)");
jLabel4.setText("minute(s)");
jLabel5.setText("second(s)");
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addGap(21, 21, 21)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(spnHour, javax.swing.GroupLayout.DEFAULT_SIZE, 36, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel3)
.addGap(16, 16, 16)
.addComponent(spnMinute, javax.swing.GroupLayout.PREFERRED_SIZE, 37, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel4)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(spnSeconds, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jLabel5))
.addGroup(jPanel1Layout.createSequentialGroup()
.addComponent(jLabel2)
.addGap(18, 18, 18)
.addComponent(cmbAction, javax.swing.GroupLayout.PREFERRED_SIZE, 101, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnGo)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(btnCancel)))
.addContainerGap())
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel1)
.addComponent(jLabel5)
.addComponent(spnHour, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel4)
.addComponent(spnSeconds, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(spnMinute, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jLabel3))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jLabel2)
.addComponent(cmbAction, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(btnGo)
.addComponent(btnCancel))
.addGap(119, 119, 119))
);
menuFile.setText("File");
itemExit.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.ALT_MASK));
itemExit.setText("Exit");
itemExit.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
itemExitActionPerformed(evt);
}
});
menuFile.add(itemExit);
jMenuBar1.add(menuFile);
menuAbout.setText("About");
menuAbout.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
menuAboutMouseClicked(evt);
}
});
jMenuBar1.add(menuAbout);
setJMenuBar(jMenuBar1);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, 75, Short.MAX_VALUE)
);
java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
setBounds((screenSize.width-368)/2, (screenSize.height-130)/2, 368, 130);
}// </editor>
private void btnGoActionPerformed(java.awt.event.ActionEvent evt) {
hour = (Integer) spnHour.getValue()*3600;
minute = (Integer) spnMinute.getValue()*60;
second = (Integer) spnSeconds.getValue();
timer = hour + minute + second;
String comment = "Komputer ini akan "+cmbAction.getSelectedItem()+" dalam waktu "+spnHour.getValue()+" jam "+spnMinute.getValue()+" menit "+spnSeconds.getValue()+" detik.";
if(cmbAction.getSelectedItem().equals("Shutdown"))
{
pb = new ProcessBuilder("C:/WINDOWS/system32/shutdown.exe","-s","-t",timer.toString(),"-c",comment);
try
{
pb.start();
}
catch (IOException ex)
{
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
else if(cmbAction.getSelectedItem().equals("Restart"))
{
pb = new ProcessBuilder("C:/WINDOWS/system32/shutdown.exe","-r","-t",timer.toString(),"-c",comment);
try
{
pb.start();
}
catch (IOException ex)
{
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
else
{
pb = new ProcessBuilder("C:/WINDOWS/system32/shutdown.exe","-l","-t",timer.toString(),"-c",comment);
try
{
pb.start();
}
catch (IOException ex)
{
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
btnCancel.setEnabled(true);
btnGo.setEnabled(false);
spnHour.setEnabled(false);
spnMinute.setEnabled(false);
spnSeconds.setEnabled(false);
cmbAction.setEnabled(false);
}
private void btnCancelActionPerformed(java.awt.event.ActionEvent evt) {
pb = new ProcessBuilder("C:/WINDOWS/system32/shutdown.exe","-a");
try {
pb.start();
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
btnCancel.setEnabled(false);
btnGo.setEnabled(true);
spnHour.setEnabled(true);
spnMinute.setEnabled(true);
spnSeconds.setEnabled(true);
cmbAction.setEnabled(true);
}
private void itemExitActionPerformed(java.awt.event.ActionEvent evt) {
System.exit(0);
}
private void menuAboutMouseClicked(java.awt.event.MouseEvent evt) {
new About().setVisible(true);
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
try {
new Main().setVisible(true);
} catch (ClassNotFoundException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
} catch (UnsupportedLookAndFeelException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton btnCancel;
private javax.swing.JButton btnGo;
private javax.swing.JComboBox cmbAction;
private javax.swing.JMenuItem itemExit;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JLabel jLabel4;
private javax.swing.JLabel jLabel5;
private javax.swing.JMenuBar jMenuBar1;
private javax.swing.JPanel jPanel1;
private javax.swing.JMenu menuAbout;
private javax.swing.JMenu menuFile;
private javax.swing.JSpinner spnHour;
private javax.swing.JSpinner spnMinute;
private javax.swing.JSpinner spnSeconds;
// End of variables declaration
}
