I'm going to explain about my program, Notepad.java, a swing based program. It just look like windows operating system's notepad.
We can implement all the typical text editor functionality with Java. My program could give you a good start.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.event.*;
/**
* Notepad class
* @author SANTHOSH REDDY MANDADI
* @since 20-April-2007
* @version 1.0
*/
public class Notepad extends JFrame implements ActionListener,ItemListener,MenuListener,KeyListener
{
FileOutputStream fos;
FileInputStream fis;
JFileChooser dialog;
JOptionPane msgbox;
boolean modified=false;
String str;
JMenuBar menubar;
JMenu file,edit,help;
JMenuItem newfile,savefile,openfile,exit,cut,copy,paste,about,selall;
JTextArea disp;
JScrollPane scrlpane;
public Notepad()
{
disp=new JTextArea();
scrlpane=new JScrollPane(disp);//,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
menubar=new JMenuBar();
dialog=new JFileChooser();
msgbox=new JOptionPane();
file=new JMenu("File"); file.setMnemonic('F');
edit=new JMenu("Edit"); edit.setMnemonic('E');
help=new JMenu("Help"); help.setMnemonic('H');
newfile=new JMenuItem("New"); newfile.setMnemonic('N');
openfile=new JMenuItem("Open"); openfile.setMnemonic('O');
savefile=new JMenuItem("Save"); savefile.setMnemonic('S');
exit=new JMenuItem("Exit"); exit.setMnemonic('x');
cut=new JMenuItem("Cut"); cut.setMnemonic('C');
copy=new JMenuItem("Copy"); copy.setMnemonic('o');
paste=new JMenuItem("Paste"); paste.setMnemonic('P');
selall=new JMenuItem("Select All"); selall.setMnemonic('A');
about=new JMenuItem("About"); about.setMnemonic('A');
cut.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X,InputEvent.CTRL_MASK,true));
copy.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C,InputEvent.CTRL_MASK,true));
paste.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_P,InputEvent.CTRL_MASK,true));
openfile.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O,InputEvent.CTRL_MASK,true));
savefile.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S,InputEvent.CTRL_MASK,true));
newfile.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_N,InputEvent.CTRL_MASK,true));
file.add(newfile);
file.add(openfile);
file.add(savefile);
file.addSeparator();
file.add(exit);
edit.add(cut);
edit.add(copy);
edit.add(paste);
edit.addSeparator();
edit.add(selall);
help.add(about);
menubar.add(file);
menubar.add(edit);
menubar.add(help);
Container c=getContentPane();
getRootPane().setJMenuBar(menubar);
c.add(scrlpane);
setSize(500,500);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
setTitle("Untitled - Notepad");
savefile.addActionListener(this);
openfile.addActionListener(this);
exit.addActionListener(this);
cut.addActionListener(this);
copy.addActionListener(this);
paste.addActionListener(this);
selall.addActionListener(this);
newfile.addActionListener(this);
edit.addMenuListener(this);
disp.addKeyListener(this);
}
public void keyPressed(KeyEvent e)
{
//System.out.println("Press");
}
public void keyReleased(KeyEvent e)
{
//System.out.println("Release");
}
public void keyTyped(KeyEvent e)
{
String str=KeyEvent.getKeyModifiersText(InputEvent.CTRL_MASK);
if(!str.equals("Ctrl"))
modified=true;
}
public void menuSelected(MenuEvent ml)
{
//System.out.println("Sele");
if(ml.getSource()==edit)
{
if(disp.getSelectedText()==null)
{
cut.setEnabled(false);
copy.setEnabled(false);
}
else
{
cut.setEnabled(true);
copy.setEnabled(true);
}
}
}
public void menuDeselected(MenuEvent ml)
{
//System.out.println("DeSele");
}
public void menuCanceled(MenuEvent ml)
{
//System.out.println("Can");
}
public void actionPerformed(ActionEvent ae){
if(ae.getSource()==savefile)
{
if(getTitle().equals("Untitled - Notepad"))
saveFile(0);
else if(modified)
saveFile(1);
}
else if(ae.getSource()==openfile)
{
int x;
if(modified)
{
x=isModified();
if(x==1)
{
if(getTitle().equals("Untitled - Notepad"))
saveFile(0);
else
saveFile(1);
openFile();
}
else if(x!=3) openFile();
}
else openFile();
}
else if(ae.getSource()==exit)
{
int x;
if(modified)
{
x=isModified();
if(x==1)
{
if(getTitle().equals("Untitled - Notepad"))
saveFile(0);
else
saveFile(1);
}
else if(x==2) System.exit(0);
}
else System.exit(0);
}
else if(ae.getSource()==newfile)
{
int x;
if(modified)
{
x=isModified();
if(x==1)
{
if(getTitle().equals("Untitled - Notepad"))
saveFile(0);
else
saveFile(1);
}
else if(x!=3){
disp.setText("");
setTitle("Untitled - Notepad");
modified=false;
}
}
else{
disp.setText("");
setTitle("Untitled - Notepad");
modified=false;
}
}
else if(ae.getSource()==cut)
{
disp.cut();
}
else if(ae.getSource()==copy)
{
disp.copy();
}
else if(ae.getSource()==paste)
{
disp.paste();
}
else if(ae.getSource()==selall)
{
disp.selectAll();
}
}
public void saveFile(int saveflag)
{
File f;
try
{
if(saveflag==0)
{
int x=dialog.showSaveDialog(this);
if(x==0){
f=dialog.getSelectedFile();
fos=new FileOutputStream(f);
setTitle(f.getPath());
PrintStream ps=new PrintStream(fos);
ps.print(disp.getText());
modified=false;
}
}
else
{
f=new File(getTitle());
fos=new FileOutputStream(f);
setTitle(f.getPath());
PrintStream ps=new PrintStream(fos);
ps.print(disp.getText());
modified=false;
}
}catch(Exception e){}
}
public void openFile()
{
int x=dialog.showOpenDialog(this);
if(x==0){
try
{
File f=dialog.getSelectedFile();
fis=new FileInputStream(f);
setTitle(f.getPath());
disp.setText("");
BufferedReader br=new BufferedReader(new InputStreamReader(fis));
while((str=br.readLine())!=null)
disp.append(str+"\n");
disp.replaceRange("",disp.getText().length()-1,disp.getText().length());
modified=false;
}catch(Exception e){}
}
}
public int isModified()
{
int x=JOptionPane.showConfirmDialog(this, "The text in the "+getTitle()+" has changed\nDo you want to save it", "Notepad", JOptionPane.YES_NO_CANCEL_OPTION,JOptionPane.WARNING_MESSAGE);
if(x==JOptionPane.YES_OPTION) return 1;
else if(x==JOptionPane.NO_OPTION) return 2;
else return 3;
}
public void itemStateChanged(ItemEvent ie){}
public static void main(String[] args)
{
new Notepad();
}
}
I've tested this program on Java 1.4, 1.5, 1.6 and 1.5 versions of Sun Microsystem's Java.
If you've sometime, why don't you checkout other Java programs I've developed.