JTextArea append() not working?

[Jon Mattson]

So I'm planning to make a level editor for a game and to do that I must be able to read and save files. Now I'm making a program that opens a textfile and shows the text in a JTextArea but the append() method doesn't work where it's supposed to. It seems it stops working after I opened a dialog with filechooser. So what's wrong?

Here's the code:

  
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
import java.io.*;
 
public class LevelEditor implements ActionListener {

File input;
File output;
    FileReader in;
    JFileChooser fc = new JFileChooser();
    String newline = "/n";
    JTextArea log;
    int c;

    public JMenuBar createMenuBar() {
        //Where the GUI is created:
        JMenuBar menuBar;
        JMenu menu, submenu;
        JMenuItem menuItem;
 
        //Create the menu bar.
        menuBar = new JMenuBar();
 
        //Build the first menu.
        menu = new JMenu("File");
        menu.setMnemonic(KeyEvent.VK_A);
        menuBar.add(menu);
 
        //a group of JMenuItems
        menuItem = new JMenuItem("Open", KeyEvent.VK_O);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, ActionEvent.ALT_MASK));
        menuItem.addActionListener(this);
        menu.add(menuItem);
        
        menuItem = new JMenuItem("Save", KeyEvent.VK_S);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, ActionEvent.ALT_MASK));
        menuItem.addActionListener(this);
        menu.add(menuItem);
 
        menuItem = new JMenuItem("Close", KeyEvent.VK_F4);
        menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_F4, ActionEvent.ALT_MASK));
        menuItem.addActionListener(this);
        menu.add(menuItem);
        
        return menuBar;
    }

    public Container createContentPane() {
    
        JPanel contentPane = new JPanel(new GridLayout(0,1));
        contentPane.setBackground(Color.white);
        contentPane.setPreferredSize(new Dimension(500, 500));
        contentPane.setOpaque(true);
        
        log = new JTextArea(5,50);
        log.setEditable(false);
        
        contentPane.add(log);
 
        return contentPane;
    }
    
    
    public void actionPerformed(ActionEvent e) {
    
    String event = e.getActionCommand();
    if (event.equals("Close")){
            log.append("Close");
    }else if (event.equals("Open")) {
            log.append("Open");
        int returnVal = fc.showOpenDialog(createContentPane());
            
        if (returnVal == JFileChooser.APPROVE_OPTION) {
        input = fc.getSelectedFile();
        try{
        in = new FileReader(input);
                while ((c = in.read()) != -1){
                    log.append(String.valueOf(c));
                System.out.print((char) c);
                }
        }
        catch(IOException io){
        System.out.println(io);
        }
            } else {
                System.out.println("Open command cancelled by user.");
            }
        
    }else if (event.equals("Save")) {
            log.append("Save");
        fc.showSaveDialog(createContentPane());
        }
    }
 
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);
 
        //Create and set up the window.
        JFrame frame = new JFrame("Level Editor");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        //Set the menu bar
        LevelEditor editor = new LevelEditor();
        frame.setJMenuBar(editor.createMenuBar());
        frame.setContentPane(editor.createContentPane());
 
        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }
    
    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}  

[Ernest Friedman-Hill]

Each time you call createContentPane(), a new JTextArea is created and the member variable "log" set to point to it. The original one is still on the screen, but "log" isn't referring to it anymore. You're then appending to another JTextArea that isn't visible!

I don't understand why you're calling this method repeatedly, when you've got a member variable to refer to everything else; just store the return value the very first time you call it into a member, and use that member everywhere else.

[Jon Mattson]

Sweet it's working now, thx alot

Now I've been trying to make it able to save the text. I wrote some code but it doesn't seem to work. It saves a file but it's empty. If I load a file and save it without changing anything it works.

Here is the code:

 
else if (event.equals("Save")) {
        int returnVal = fc.showSaveDialog(container);
            
        if (returnVal == JFileChooser.APPROVE_OPTION) {
        output = fc.getSelectedFile();
        try{
        out = new FileWriter(output);
               for (int i = 0; i < log.getText().length(); i++){
                    out.write(log.getText().charAt(i));
                }
        }
        catch(IOException io){
        System.out.println(io);
        }
            } else {
                System.out.println("Save command cancelled by user.");
            }
        }
 
  

I also tried using PrintWriters methods print(string) and write(string) but they didn't work either.

[Paul Clapham]

You didn't close the writer after you finished using it. Since writing to disk files happens in chunks of several K bytes at a time (because that's how the operating system deals with files), you're losing the last chunk. Which is probably the whole thing. Close the writer in a finally block like this:

out = null;
try{
  out = new FileWriter(output);
  for (int i = 0; i < log.getText().length(); i++){
    out.write(log.getText().charAt(i));
  }
}
  catch(IOException io){
    // System.out.println(io); // Not enough information...
    io.printStackTrace(); // More useful information
  }
  finally{
    if (out != null){
      out.close();
    }
}