JText Area..searching and replacing text

[Ben Jordan]

import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowAdapter;
import java.io.File;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
 
public class FileViewer extends JPanel
{
private File file;
private JScrollPane scrollPane;
private JTextArea display;
 
public FileViewer ()
{
setLayout(new GridLayout(1,1));
display = new JTextArea();
display.setFont(new Font("Courier", Font.PLAIN, 12));
display.setEditable(false);
scrollPane = new JScrollPane(display);
add(scrollPane);
}
 
public void setFile (File file) throws IOException
{
this.file = file;
refreshContents();
}
 
private void refreshContents () throws IOException
{
BufferedReader in = new BufferedReader(new FileReader(file));
StringWriter out = new StringWriter();
PrintWriter pout = new PrintWriter(out);
 
for (String str = in.readLine();
 str != null;
 str = in.readLine())
{
pout.println(str);
}
pout.flush();
 
String contents = out.toString();
display.setText(contents);
pout.close();
out.close();
in.close();
}
 
public static JFrame createFileViewerInFrame (String filename)
throws IOException
{
FileViewer viewer = new FileViewer();
viewer.setFile(new File(filename));
 
final JFrame frame = new JFrame(filename);
frame.getContentPane().setLayout(new GridLayout(1,1));
frame.add(viewer);
 
// This handles the window's close button.
frame.addWindowListener(new WindowAdapter ()
{
public void windowClosing (WindowEvent event)
{
exit(frame);
}
});
 
setMenuBar(frame, viewer);
 
frame.setVisible(true);
frame.setSize(600, 800);
 
return frame;
}
 
private static void setMenuBar (final JFrame frame, FileViewer viewer)
{
JMenuBar menuBar = new JMenuBar();
 
JMenu fileMenu = new JMenu("File");
menuBar.add(fileMenu);
 
JMenuItem exitMenuItem = new JMenuItem("Exit");
fileMenu.add(exitMenuItem);
exitMenuItem.addActionListener(new ActionListener ()
{
public void actionPerformed (ActionEvent event)
{
exit(frame);
}
});
 
frame.setJMenuBar(menuBar);
}
 
/*
  What follows here is a rather convoluted mess of multithreading
  code that is not actually necessary.  This is being done to avoid
  calling System.exit() to exit the virtual machine.  The only
  other way to exit the virtual machine is for all non-daemon
  threads to stop.  So we have to make sure there is at least one
  non-daemon thread (the main thread) AND we have to make sure
  there are no other non-daemon threads.
 */
private static boolean exit = false;
private static Object lockObject = new Object();
 
public static void main (String [] args) throws Exception
{
final String filename = args[0];
Thread t = new Thread ()
{
public void run ()
{
synchronized (lockObject)
{
try
{
/*
  This will start the AWT event queue which
  we want to be started as a daemon thread.
  The only way this can be assured is if
  the parent thread (this thread) is also
  a daemon thread.
 */
createFileViewerInFrame(filename).setVisible(true);
}
catch (IOException ioe)
{
ioe.printStackTrace();
FileViewer.exit(null);
 
}
}
}
};
t.setDaemon(true);  // Make it a daemon.
synchronized (lockObject)
{
t.start();
while (!exit)
{
try
{
/*
  Wait here until notified.  Since this thread is
  NOT a daemon thread, this keeps the virtual machine
  alive.
 */
lockObject.wait();
}
catch (InterruptedException checkAgain) {}
}
}
}
 
public static void exit (JFrame frame)
{
synchronized (lockObject)
{
if (frame != null)
{
frame.setVisible(false);
/*
  We need to dispose of the frame so that the AWT event
  queue will not keep the virtual machine around waiting
  for GUI events.
 */
frame.dispose();
}
exit = true;
/*
  Tell the main thread it is time to stop waiting.
 */
lockObject.notify();
}
}
}
 

This is my code. I need to know how to serach the area for certain text and then be able to replace it. I know I will have to use the replace () method somewhere in there to replace the text but not sure on how to search for it.
ANy help youc ould provide woule be greatly appricated.

Thanks,
Ben Jordan

[Campbell Ritchie]

Welcome to the Ranch.

At least three ways on doing it

Basic: Use the String class which has indexOf() methods; you can repeatedly find a particular bit of text. it has replace() and replaceAll() method which creates a new String object. You doubtless already know you can't change a String.

Not quite so basic: Use the StringBuilder clasa (a more recent replacement for StringBuffer). It has methods for finding a particular index, and inserting or deleting text.

Maybe more advanced. Find the StrBuilder class in Jakarta Commons, which is similar to StringBuilder.

Fuller details in the API.

[Campbell Ritchie]

. . . and StringBuilder appears to have replace method too.

[Ben Jordan]

Campbell,
Thanks for the help....I should clarifiy what I mean. How would the code be? would it something like this...

 
If (JTextArea.indexof(whatever) > -1)
    JTextArea = JTextArea.replace('whatever', "WHATEVER");
 

Let me know....

Thanks,
Ben

[Paul Clapham]

No. Here's what you should do.

1. Get the text from the JTextArea into a String.

2. Consider what the earlier posts said to do with String data.

3. Put the modified String data back into the JTextArea.

[Ben Jordan]

so something like this,

String displayText = JTextArea;
If (displayText.indexof(whatever) > -1)    
JTextArea = displayText.replace('whatever', "WHATEVER");

[Campbell Ritchie]

No, 'fraid not.

Your JTextArea isn't a String. You need to get the text from it, which is in the form of a string, then you can use a replace method, or put it into a StringBuilder and use that to manipulate it.
Then you can put the text back into the text area.

Look at the API description for JTextArea. Here.

Alternatively there is one place in your coding where you already have the text in the form of a String.

[Ben Jordan]

 
searchMenuItem.addActionListener(new ActionListener ()
{
public void actionPerformed (ActionEvent event)
{


String text = viewer.display.getText();
String a = JOptionPane.showInputDialog(null, "Please enter a chacter to search for","Dwelling Type", JOptionPane.QUESTION_MESSAGE);
int index = text.indexOf(a, viewer.display.getCaret().getDot());
if (index > -1)
{
viewer.display.getCaret().setDot(index);
}
}
});
replaceMenuItem.addActionListener(new ActionListener ()
{
public void actionPerformed (ActionEvent event)
{


String text = viewer.display.getText();
String a = JOptionPane.showInputDialog(null, "Please enter a chacter to search for","Search", JOptionPane.QUESTION_MESSAGE);
String b = JOptionPane.showInputDialog(null, "Please enter a chacter to replace for","Replace", JOptionPane.QUESTION_MESSAGE);
int index = text.indexOf(a, viewer.display.getCaret().getDot());
if (index > -1)
{
int length = b.length();
viewer.display.replaceRange(b,index,index + length );
}
}
});
 

this works...I spent a lot time working on this one last night,,,

[Campbell Ritchie]

Well done getting it to work.