how to open a file in a JTextArea

I hope the code below will solve ur problem,Parul --

/*

This program lets the user edit short text files in a window. A "File"

menu provides the following commands:

New -- Clears all text from the window.

Open -- Let's the user select a file and loads up to 100

lines of text form that file into the window. The

previous contents of the window are lost.

Save -- Let's the user specify an ouput file and saves

the contents of the window in that file.

Quit -- Closes the window and ends the program.

This class uses the non-standard class TextReader.

*/

import java.io.*;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class TrivialEdit extends JFrame {

public static void main(String[] args) {

// The main program just opens a window belonging to this

// TrivialEdit class. Then the window takes care of itself

// until the program is ended with the Quit command or

// when the user closes the window.

new TrivialEdit();

}

private JTextArea text;// Holds the text that is displayed in the window.

public TrivialEdit() {

// Add a menu bar and a JTextArea to the window, and show it

// on the screen. The first line of this routine calls the

// constructor from the superclass to specify a title for the

// window. The pack() command sets the size of the window to

// be just large enough to hold its contents.

super("A Trivial Editor");

setJMenuBar(makeMenus());

text = new JTextArea(25,50);

text.setBackground(Color.white);

text.setMargin( new Insets(3,5,0,0) );

JScrollPane scroller = new JScrollPane(text);

setContentPane(scroller);

setDefaultCloseOperation(EXIT_ON_CLOSE);

pack();

setLocation(50,50);

show();

}

private JMenuBar makeMenus() {

// Create and return a menu bar containing a single menu, the

// File menu. This menu contains four commands, and each

// command has a keyboard equivalent.

ActionListener listener = new ActionListener() {

// An object that will serve as listener for menu items.

public void actionPerformed(ActionEvent evt) {

// This will be called when the user makes a selection

// from the File menu. This routine just checks

// which command was selected and calls another

// routine to carry out the command.

String cmd = evt.getActionCommand();

if (cmd.equals("New"))

doNew();

else if (cmd.equals("Open..."))

doOpen();

else if (cmd.equals("Save..."))

doSave();

else if (cmd.equals("Quit"))

doQuit();

}

};

JMenu fileMenu = new JMenu("File");

JMenuItem newCmd = new JMenuItem("New");

newCmd.setAccelerator( KeyStroke.getKeyStroke("ctrl N") );

newCmd.addActionListener(listener);

fileMenu.add(newCmd);

JMenuItem openCmd = new JMenuItem("Open...");

openCmd.setAccelerator( KeyStroke.getKeyStroke("ctrl O") );

openCmd.addActionListener(listener);

fileMenu.add(openCmd);

JMenuItem saveCmd = new JMenuItem("Save...");

saveCmd.setAccelerator( KeyStroke.getKeyStroke("ctrl S") );

saveCmd.addActionListener(listener);

fileMenu.add(saveCmd);

JMenuItem quitCmd = new JMenuItem("Quit");

quitCmd.setAccelerator( KeyStroke.getKeyStroke("ctrl Q") );

quitCmd.addActionListener(listener);

fileMenu.add(quitCmd);

JMenuBar bar = new JMenuBar();

bar.add(fileMenu);

return bar;

} // end makeMenus()

private void doNew() {

// Carry out the "New" command from the File menu by

// by clearing all the text from the JTextArea.

text.setText("");

}

private void doSave() {

// Carry out the Save command by letting the user specify

// an output file and writing the text from the JTextArea

// to that file.

File file; // The file that the user wants to save.

JFileChooser fd; // File dialog that lets the user specify the file.

fd = new JFileChooser(new File("."));

fd.setDialogTitle("Save Text As...");

int action = fd.showSaveDialog(this);

if (action != JFileChooser.APPROVE_OPTION) {

// User has canceled, or an error occurred.

return;

}

file = fd.getSelectedFile();

if (file.exists()) {

// If file already exists, ask before replacing it.

action = JOptionPane.showConfirmDialog(this,

"Replace existing file?");

if (action != JOptionPane.YES_OPTION)

return;

}

try {

// Create a PrintWriter for writing to the specified

// file and write the text from the window to that stream.

PrintWriter out = new PrintWriter(new FileWriter(file));

String contents = text.getText();

out.print(contents);

if (out.checkError())

throw new IOException("Error while writing to file.");

out.close();

}

catch (IOException e) {

// Some error has occured while trying to write.

// Show an error message.

JOptionPane.showMessageDialog(this,

"Sorry, an error has occurred:\n" + e.getMessage());

}

}

private void doOpen() {

// Carry out the Open command by letting the user specify

// the file to be opened and reading up to 100 lines from

// that file. The text from the file replaces the text

// in the JTextArea.

File file; // The file that the user wants to open.

JFileChooser fd; // File dialog that lets the user specify the file.

fd = new JFileChooser(new File("."));

fd.setDialogTitle("Open File...");

int action = fd.showOpenDialog(this);

if (action != JFileChooser.APPROVE_OPTION) {

// User canceled the dialog, or an error occurred.

return;

}

file = fd.getSelectedFile();

try {

// Read lines from the file until end-of-file is detected,

// or until 100 lines have been read. The lines are added

// to the JTextArea, with a line feed after each line.

TextReader in = new TextReader(new FileReader(file));

String line;

text.setText("");

int lineCt = 0;

while (lineCt < 100 && in.peek() != '\0') {

line = in.getln();

text.append(line + '\n');

lineCt++;

}

if (in.eof() == false)

text.append("\n\n******* Text truncated to 100 lines! *******\n");

in.close();

}

catch (Exception e) {

// Some error has occured while trying to read the file.

// Show an error message.

JOptionPane.showMessageDialog(this,

"Sorry, some error occurred:\n" + e.getMessage());

}

}

private void doQuit() {

// Carry out the Quit command by exiting the program.

System.exit(0);

}

} // end class TrivialEdit

Amit Gupta

amit.g79a at 2007-7-15 21:46:37 >

> my program is dat it is not able to get the TextReader class

Thats because TextReader does not exist in the API.

You need to learn how to read the API. Two posters have suggested that you use the read(...) method of text area. It is simply two lines of code:

FileReader reader = new FileReader(....);

textArea.read(reader, null);

Just because someone posts you 100 lines of code doesn't mean the suggestion will work. Learn to do some reading on you own thats what the API is for.

camickra at 2007-7-15 21:46:37 >