TextEditor

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

/*
 * A simple Text Editor.  This demonstrates the use of a
 * JFileChooser for the user to select a file to read from or write to.
 * It also demonstrates reading and writing text files.
 */
public class TextEditor implements ActionListener {
    // Size of editing text area.
    private static final int NUM_ROWS = 25;
    private static final int NUM_COLS = 50;

    // Buttons to save and load files.
    private JButton saveButton, loadButton;

    // Area where the user does the editing
    private JTextArea text;

    // Creates the GUI
    public TextEditor() {
        JFrame frame = new JFrame();
        JPanel buttonPanel = new JPanel();
        saveButton = new JButton("Save File");
        loadButton = new JButton("Load File");
        buttonPanel.add(saveButton);
        buttonPanel.add(loadButton);

        text = new JTextArea(NUM_ROWS, NUM_COLS);
        text.setFont(new Font("System", Font.PLAIN, 24));
        JScrollPane textScroller = new JScrollPane(text);
        Container contentPane = frame.getContentPane();
        contentPane.add(textScroller, BorderLayout.CENTER);
        contentPane.add(buttonPanel, BorderLayout.NORTH);

        saveButton.addActionListener(this);
        loadButton.addActionListener(this);

        frame.pack();
        frame.setVisible(true);
    }

    // Listener for button clicks that loads the
    // specified files and puts it in the
    // editor.
    public void actionPerformed(ActionEvent event) {
        if (event.getSource() == saveButton) {
            saveFile();
        } else {
            loadFile();
        }
    }

    // Display a file chooser so the user can select a file
    // to save to. Then write the contents of the text area
    // to that file. Does nothing if the user cancels out
    // of the file chooser.
    private void saveFile() {
        File file;

        // create and display dialog box to get file name
        JFileChooser dialog = new JFileChooser();

        // Make sure the user didn't cancel the file chooser
        if (dialog.showSaveDialog(text) == JFileChooser.APPROVE_OPTION) {

            // Get the file the user selected
            file = dialog.getSelectedFile();

            try {
                // Now write to the file
                PrintWriter output = new PrintWriter(new FileWriter(file));
                output.println(text.getText());
                output.close();
            } catch (IOException e) {
                JOptionPane.showMessageDialog(text, "Can't save file "
                        + e.getMessage());
            }
        }
    }

    // Display a file chooser so the user can select a file to load.
    // Then load the file into the editing area. Does nothing if
    // the user cancels the file chooser.
    private void loadFile() {
        String line;
        File file;

        // create and display dialog box to get file name
        JFileChooser dialog = new JFileChooser();

        // Make sure the user did not cancel.
        if (dialog.showOpenDialog(text) == JFileChooser.APPROVE_OPTION) {
            // Find out which file the user selected.
            file = dialog.getSelectedFile();

            try {
                // Open the file.
                BufferedReader input = new BufferedReader(new FileReader(file));

                // Clear the editing area
                text.setText("");

                // Fill up the ediitng area with the contents of the file being
                // read.
                line = input.readLine();
                while (line != null) {
                    text.append(line + "\n");
                    line = input.readLine();
                }

                // Close the file
                input.close();
            } catch (IOException e) {
                JOptionPane.showMessageDialog(text, "Can't load file "
                        + e.getMessage());
            }
        }
    }

    // Main program for the application
    public static void main(String[] args) {
        new TextEditor();
    }
}