How to create Notepad in Java?

Introduction

To build a Notepad in Java we require basic knowledge of java and file operations. Java provides default packages such as Abstract Window Toolkit (AWT) & Swing to create a user interface (UI) for desktop applications.

The notepad project we are going to build is a desktop application just like the notepad or text editor we usually see on our desktop. Some of the features of Notepad in Java are Menu Bar for Creating a new file, Edit, View, and saving a file.

We need Eclipse or NetBeans to implement this project. Create a new project named Notepad, add a new package with the same name Notepad, and paste the following code into the file Notepad.java.

Code for Notepad in Java

import java.io.*;
import java.awt.datatransfer.*;
import java.util.*;
import javax.swing.*;
import java.lang.*;
import java.awt.*;
import java.awt.event.*;

public class Notepad extends JFrame implements ActionListener, WindowListener {		
	File fnameContainer;
	JTextArea jta  =new JTextArea();

	public void windowDeactivated(WindowEvent e){}
	public void windowActivated(WindowEvent e){}
	public void windowDeiconified(WindowEvent e){}
	public void windowIconified(WindowEvent e){}
	public void windowClosed(WindowEvent e){}	
	public void windowClosing(WindowEvent e) { Exiting(); }	
	public void windowOpened(WindowEvent e){}vm	public void Exiting() {System.exit(0);}

	public void EditFile(String fname) throws IOException {	
		BufferedReader d=new BufferedReader(new InputStreamReader(new FileInputStream(fname)));
		String s;
		jta.setText("");	
		setCursor(new Cursor(Cursor.WAIT_CURSOR));		
		while((s=d.readLine())!= null) {
			jta.setText(jta.getText()+s+"\r\n");
		}	
		setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
		d.close();
	}

	public void createMenuItem(JMenu jm,String txt){
		JMenuItem jmi=new JMenuItem(txt);
		jmi.addActionListener(this);
		jm.add(jmi);
	}

	public void SaveFileAs(String fname) throws IOException {
		setCursor(new Cursor(Cursor.WAIT_CURSOR));
		DataOutputStream dos=new DataOutputStream(new FileOutputStream(fname));
		dos.writeBytes(jta.getText());
		dos.close();		
		setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
	}
	
	public void actionPerformed(ActionEvent e){	
		JFileChooser jfc=new JFileChooser();
		
		if(e.getActionCommand().equals("New")){ 
			this.setTitle("Untitled.txt - Notepad");
			jta.setText("");
			fnameContainer=null;		
		}
		else if(e.getActionCommand().equals("Open")){
			int ret=jfc.showDialog(null,"Open");			
			if(ret == JFileChooser.APPROVE_OPTION)
			{
				try{
					File fyl=jfc.getSelectedFile();
					OpenFile(fyl.getAbsolutePath());
					this.setTitle(fyl.getName()+ " - Notepad");
					fnameContainer=fyl;
				}
				catch(IOException ers){}
			}
			
		}
		else if(e.getActionCommand().equals("Save")){
			if(fnameContainer != null){
				jfc.setCurrentDirectory(fnameContainer);		
				jfc.setSelectedFile(fnameContainer);
			}
			else {
				jfc.setSelectedFile(new File("Untitled.txt"));
			}
			
			int ret=jfc.showSaveDialog(null);				
			if(ret == JFileChooser.APPROVE_OPTION){
				try{
					
					File fyl=jfc.getSelectedFile();
					SaveFile(fyl.getAbsolutePath());
					this.setTitle(fyl.getName()+ " - Notepad");
					fnameContainer=fyl;				
				}
				catch(Exception ers2){}
			}			
		}
		else if(e.getActionCommand().equals("Exit")){
			Exiting();
		}
		else if(e.getActionCommand().equals("Copy")){
			jta.copy();
		}
		else if(e.getActionCommand().equals("Paste")){
			jta.paste();
		}
		else if(e.getActionCommand().equals("About Notepad")){ 
			JOptionPane.showMessageDialog(this,"","Notepad",JOptionPane.INFORMATION_MESSAGE);
		}
		else if(e.getActionCommand().equals("Cut")){
			jta.cut();
		}
	}
	
	public void OpenFile(String fname) throws IOException {	
		BufferedReader d=new BufferedReader(new InputStreamReader(new FileInputStream(fname)));
		String s;
		jta.setText("");	
		setCursor(new Cursor(Cursor.WAIT_CURSOR));		
		while((s=d.readLine())!= null) {
			jta.setText(jta.getText()+s+"\r\n");
		}	
		setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
		d.close();
	}
	
	public void SaveFile(String fname) throws IOException {
		setCursor(new Cursor(Cursor.WAIT_CURSOR));
		DataOutputStream dos=new DataOutputStream(new FileOutputStream(fname));
		dos.writeBytes(jta.getText());
		dos.close();		
		setCursor(new Cursor(Cursor.DEFAULT_CURSOR));
	}

	public static void main (String[] args) {
		Notepad notp=new Notepad();	
	}
	
	public Notepad(){

		Font fnt=new Font("Arial",Font.PLAIN,15);
		Container con=getContentPane();		
		JMenuBar jmb=new JMenuBar();
		JMenu jmfile = new JMenu("File");
		JMenu jmedit = new JMenu("Edit");
		JMenu jmhelp = new JMenu("Help");
		
		con.setLayout(new BorderLayout());
		JScrollPane sbrText = new JScrollPane(jta);
		sbrText.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
		sbrText.setVisible(true);				
		jta.setFont(fnt);
		jta.setLineWrap(true);
		jta.setWrapStyleWord(true);		
		con.add(sbrText);
		createMenuItem(jmfile,"New");
		createMenuItem(jmfile,"Open");
		createMenuItem(jmfile,"Save");
		jmfile.addSeparator();
		createMenuItem(jmfile,"Exit");		
		createMenuItem(jmedit,"Cut");
		createMenuItem(jmedit,"Copy");
		createMenuItem(jmedit,"Paste");		
		createMenuItem(jmhelp,"About Notepad");		
		jmb.add(jmfile);
		jmb.add(jmedit);
		jmb.add(jmhelp);		
		setJMenuBar(jmb);
		addWindowListener(this);
		setSize(500,500);
		setTitle("Untitled.txt - Notepad");				
		setVisible(true);	
	}
}