TextEditor.java
<![CDATA[
/* Imports */
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.nio.*;
import javax.swing.*;
/**
* TextEditor.java
*
* Simple text editor that shows how to read and write files.
*
* @author D.Barry
**/
public class TextEditor implements Runnable{
/* Constants */
private static final String NAME = "TextEditor";
private static final int WIDTH = 500;
private static final int HEIGHT = 500;
/* Instance variables */
private String content;
private File file;
private JTextArea textArea;
/**
* main()
*
* Entry point into the program.
*
* @param args The arguments to the program.
**/
public static void main(String[] args){
if(args.length == 1){
/* Create a new program */
TextEditor te = new TextEditor(args[0]);
/* Run this program in the EDT thread */
SwingUtilities.invokeLater(te);
}else{
/* Display an error message */
error();
}
}
/**
* TextEditor()
*
* The text editor to be displayed on screen.
*
* @param path The name of the file to be loaded.
**/
public TextEditor(String path){
/* Make a file object so we can start inferring some truths */
file = new File(path);
/* Check if a file or folder exists */
if(file.exists()){
/* Check if we have a file or folder */
if(file.isDirectory()){
/* Display an error message */
error();
}
}else{
/* Create a blank file */
createFile(file);
}
/* Read the file */
content = readFile(file);
}
/**
* createFile()
*
* Create a new file.
*
* @param file The file to be created.
**/
private void createFile(File file){
try{
file.createNewFile();
}catch(IOException e){
/* Do nothing */
}
}
/**
* readFile()
*
* Read the files into a String object.
*
* @param file The file to be read.
* @return The contents on the file, otherwise NULL.
**/
private String readFile(File file){
String data = null;
FileReader fr = null;
try{
fr = new FileReader(file);
/* Create a buffer to read the bytes into */
char[] buffer = new char[(int)file.length()];
/* Make the read */
fr.read(buffer);
data = new String(buffer);
/* Close the file for everybody else */
fr.close();
}catch(IOException e){
/* Do nothing */
}finally{
/* If we did manage to open the file, don't lock it up */
if(fr != null){
/* Try to finish what we started */
try{
fr.close();
}catch(IOException e){
/* Do nothing */
}
}
}
return data;
}
/**
* writeFile()
*
* Writes the file to the disk.
*
* @param file The file to be written.
* @param data The data be be written to the disk.
**/
private void writeFile(File file, String data){
FileOutputStream out = null;
try{
out = new FileOutputStream(file);
}catch(FileNotFoundException e){
/* Handle error */
writeError();
}
try{
if(out != null){
out.write(data.getBytes());
out.close();
}
}catch(IOException e){
/* Handle error */
writeError();
}
}
/**
* writeError()
*
* Display a message box to tell the user there has been an issue, then exit
* the system.
**/
private void writeError(){
/* Display message */
JOptionPane.showMessageDialog(
null,
"Failed to write file.",
"Write Error",
JOptionPane.INFORMATION_MESSAGE
);
/* Dirty exit */
System.exit(0);
}
/**
* run()
*
* Main entry point for the GUI.
**/
public void run(){
/* Create the frame that we will put everything in */
JFrame jFrame = new JFrame(NAME);
/* Make sure that it is able to close */
jFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
/* Set the size of the frame */
jFrame.setPreferredSize(new Dimension(WIDTH, HEIGHT));
/* Create the text area */
textArea = new JTextArea();
/* Lines can be wrapped */
textArea.setLineWrap(true);
textArea.setWrapStyleWord(true);
textArea.setBorder(BorderFactory.createEmptyBorder(8, 8, 8, 8));
textArea.setText(content);
/* Add a scroll bar */
jFrame.add(new JScrollPane(textArea));
/* Listen to closing event */
jFrame.addWindowListener(
new WindowAdapter(){
/**
* windowClosing()
*
* This method captures the close event on a frame.
*
* @param e The even to cause the close.
**/
@Override
public void windowClosing(WindowEvent e){
/* Auto-save file */
writeFile(file, textArea.getText());
}
}
);
/* Put all of the elements in the frame */
jFrame.pack();
/* Make the frame visible to all */
jFrame.setVisible(true);
}
/**
* error()
*
* Displays a message that indicates the correct use of this program.
**/
private static void error(){
System.out.println(
"\nTextEditor <FILE>" +
"\n" +
"\n FILE" +
"\n" +
"\n Requires a valid file in order to be loaded, otherwise a" +
"\n new file is created. This parameter cannot be excluded" +
"\n when running the program." +
"\n"
);
/* A very bad practice hard quit from the program */
System.exit(0);
}
}
]]>