Java Programming

private javax.swing.JFileChooser browse;
private javax.swing.JButton browse_btn, search_btn, reset_btn;
private javax.swing.JTextField browse_text, search_text;
private javax.swing.JTextArea area_search;
private javax.swing.JScrollPane pane_area;
private PanelFind panel;
private java.util.concurrent.ExecutorService tread;

private java.io.File dir;
private String keyword;
private RunFind findNow;

public FindFiles(){
super(”FindFiles”);

browse = new javax.swing.JFileChooser(”.”);
browse.setAcceptAllFileFilterUsed(false);
browse.setFileSelectionMode(javax.swing.JFileChooser.DIRECTORIES_ONLY);

browse_btn = new javax.swing.JButton(”Browse”);
browse_btn.addActionListener(new Aksi() );
search_btn = new javax.swing.JButton(”Search”);
search_btn.addActionListener(new Aksi() );
reset_btn = new javax.swing.JButton(”Reset”);
reset_btn.addActionListener(new Aksi() );

browse_text = new javax.swing.JTextField();
browse_text.setForeground(java.awt.Color.BLACK);
browse_text.setEnabled(false);
search_text = new javax.swing.JTextField();

area_search = new javax.swing.JTextArea();
area_search.setEditable(false);
pane_area = new javax.swing.JScrollPane(area_search);
tread = java.util.concurrent.Executors.newCachedThreadPool();

panel = new PanelFind(this);
add(panel);

setLocation(200,200);
pack();

setResizable(false);
setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
}

public void browse(){
int valid = browse.showOpenDialog(this);
if(valid == javax.swing.JFileChooser.APPROVE_OPTION){
dir = browse.getSelectedFile();
browse_text.setText(dir.getPath());
}else{
return ;
}

}

public void search(){
keyword = search_text.getText();
area_search.setText(”");
if(keyword.length()<1){ dir ="=" findnow =" new" ex =" java.util.concurrent.Executors.newCachedThreadPool();">

public void reset(){
keyword = “”;
dir = null;
search_text.setText(”");
browse_text.setText(”");
area_search.setText(”");
}

public static void main (String[] args) {
FindFiles baru = new FindFiles();
baru.setVisible(true);
}

private class Aksi implements java.awt.event.ActionListener{

public void actionPerformed(java.awt.event.ActionEvent event){
String command = event.getActionCommand();
if(command.equals(”Browse”)){
browse();
}else if(command.equals(”Reset”)){
reset();
}else if(command.equals(”Search”)){
search();
}
}

}

private class PanelFind extends javax.swing.JPanel{

private javax.swing.JFrame parent;
private java.awt.GridBagLayout layout;
private java.awt.GridBagConstraints constrait;

public PanelFind(javax.swing.JFrame parent){

this.parent = parent;
layout = new java.awt.GridBagLayout();
constrait = new java.awt.GridBagConstraints();
constrait.insets = new java.awt.Insets(5,5,5,5);
constrait.fill = java.awt.GridBagConstraints.BOTH;

setLayout(layout);
addComp(browse_text,0,0,2,1,0,0);
addComp(browse_btn,2,0,1,1,0,0);
addComp(search_text,0,1,1,1,200,0);
addComp(reset_btn,1,1,1,1,0,0);
addComp(search_btn,2,1,1,1,0,0);
addComp(pane_area,0,2,3,1,0,400);

}

public void addComp(javax.swing.JComponent comp, int kolom, int baris, int lebar, int tinggi, int lebarmanual, int tinggimanual){
constrait.gridx = kolom;
constrait.gridy = baris;
constrait.gridwidth = lebar;
constrait.gridheight = tinggi;
constrait.ipadx = lebarmanual;
constrait.ipady = tinggimanual;
layout.setConstraints(comp, constrait);
add(comp);
}

}

private class RunFind implements Runnable{

private String key;
private int count;
private FindFiles parent;

public RunFind(FindFiles parent){
this.key = keyword.startsWith(”.”) ? keyword : “.”+keyword;
this.count = 0;
this.parent = parent;
}

public synchronized void AddFiletoArea(java.io.File folder){
if(folder.isDirectory()){
java.io.File[] files = folder.listFiles();
for(java.io.File i : files){
AddFiletoArea(i);
try{
Thread.sleep(1);
}catch(InterruptedException e){
}
}
}else{
if(folder.getName().toUpperCase().endsWith(key.toUpperCase())){
area_search.append(folder.getPath()+”\n”);
count += 1;
}
}
}

public void run(){
parent.setEnabled(false);
java.io.File[] files = dir.listFiles();
for(java.io.File i : files){
AddFiletoArea(i);
try{
Thread.sleep(1);
}catch(InterruptedException e){
}
}
area_search.append(”—-FINISH—-\n”);
area_search.append(”There Are “+count+” Files Found”);
parent.setEnabled(true);
}
}

}

Step Two - Creating a source file

Once you've created a project, you can begin to write your first Java application. The project view allows you to manage your project's files. You can select a file, and edit it, or you can add/remove files using the 'Add to project' and 'Remove from project' buttons. These can be easily recognised by the plus and minus signs on these buttons.

Figure 2.0 - Project view allows you to select, add and remove files

To write an application, we'll need to create a new source file, which we'll call "HelloWorld.java".

• Click on the 'Add to project button' (the blue folder with a green plus icon).
• As a filename, use 'HelloWorld.java'.
• Click on the 'Open' button to create the file.

Step Three - Writing your first application

Up until now, we haven't had to write any code. Now its time to get your hands dirty. Start by typing the following code into the "HelloWorld.java" file from Step Two.

package MyFirstProject;

public class HelloWorld
{
     public static void main(String args[]) throws Exception
     {
            System.out.println ("Hello world!");
            System.in.read();
     }
}

Don't worry if you're a little unsure about what the code does. We'll examine the code line by line.

1: package MyFirstProject;

This line states that the class belongs to the package MyFirstProject. A package is a collection of Java classes and interfaces. We group logically related code together in a package. As a general rule, each application should have its own unique package. Use the same name for your package as you do for your project.

2: public class HelloWorld

This line declares a new class, called "HelloWorld", and that it is publicly accessible. A class is composed of data variables (members), and functions (methods).

3: public static void main(String args[]) throws IOException

All applications written in Java share at least one thing in common - they all have a main method. You must declare a public static main method that accepts command line parameters (args), for your application to run. Our main method also declares that it could generate an I/O error when reading input from the user.

4: System.out.println ("Hello world!");

This is where our application writes a message to the user. System.out is an object that allows us to write to "standard output", which is the user's console.

5: System.in.read();

So that you can read the message before the application terminates, we need to wait for keyboard input. System.in is an object that allows us to read from "standard input", which is the sequence of characters entered by the user.

Step Four - Compiling the application

Before you can run an application, you must first compile it. A compiler takes source code (the instructions for a program), and converts it into executable instructions (a program that can be run). We'll compile the HelloWorld application now.

• From the 'Build' menu, select the 'Make "HelloWorld.java" menu item.

If you've typed in the code correctly, your application will now be ready to run. If not, carefully check your code again, and repeat.

Step Five - Running the application

Once the application is compiled, its ready to run. JBuilder runs applications in their own window, which you'll see in a moment.

• From the 'Run' menu, select the 'Run "HelloWorld" menu item, or use the shortcut of shift-F9

The HelloWorld application will then appear in a new window. You'll see the message "Hello World!", and the program will wait patiently until you press the key.

Summary

At the conclusion of this lesson, you should be able to do the following :-

1. Create a new project
2. Add files to your project
3. Write code to send messages to standard output
4. Compile code
5. Execute compiled code

• Create a new NetBeans project
• Add a JFrame Form
• Complete with two fruit labels, 2 pieces textfield (txtIPAddress and txtNamaHost) and three fruit Button (btnCheckIPAddress, btnCheckHostName and btnCheckLokal). See examples in the following figures :
  
  
  


• Type the following code on btnCheckHostName, event actionPerformed :

  01	private void btnCheckHostNameActionPerformed(java.awt.event.ActionEvent evt) {

  02

  try {

  03	String strHostName = InetAddress.getByName(txtIPAddress.getText()).getHostName();

  04	JOptionPane.showMessageDialog(null, "Host name dari IP Address '" + txtIPAddress.getText() +"' = "+ strHostName);

  05	} catch (UnknownHostException ex) {

  06	JOptionPane.showMessageDialog(null, ex);

  07	Logger.getLogger(frmIpAddress.class.getName()).log(Level.SEVERE, null, ex);

  08

  09

  }

  10

  11

  }

• Perform the necessary import libraries (import java.net.InetAddress; import javax.swing.JOptionPane;)
• Type the following code on btnCheckIPAddress, event actionPerformed :

  01	private void btnCheckIPAddressActionPerformed(java.awt.event.ActionEvent evt) {

  02

  03

  try {

  04	String strIPAddress = InetAddress.getByName(txtHostName.getText()).getHostAddress() ;

  05	JOptionPane.showMessageDialog(null, "Alamat IP dari '"+txtHostName.getText() +"' ="+ strIPAddress);

  06	} catch (UnknownHostException ex) {

  07	JOptionPane.showMessageDialog(null, ex);

  08	Logger.getLogger(frmIpAddress.class.getName()).log(Level.SEVERE, null, ex);

  09

  10

  }

  11

  }

• Type the following code in the actionPerformed event btnCheckLokal :

  01	private void btnCheckLocalActionPerformed(java.awt.event.ActionEvent evt) {

  02

  try {

  03	InetAddress AlamatInternet = InetAddress.getLocalHost();

  04	JOptionPane.showMessageDialog(null, "Host name lokal : " +AlamatInternet.getHostName());

  05	JOptionPane.showMessageDialog(null, "IP Address lokal : " +AlamatInternet.getHostAddress() );

  06	} catch (UnknownHostException ex) {

  07	JOptionPane.showMessageDialog(null, ex);

  08	Logger.getLogger(frmIpAddress.class.getName()).log(Level.SEVERE, null, ex);

  09

  10

  }

  11

  }

• Save and run the application (SHIFT + F6). Enter the IP Address and click on "Check Host Name" or enter the host name and click "Check IP Address". Check Local Host IP and not require an entry. Here are some screenshots of messages that appear :