Re: Adding SCROLLBARS to a JTextArea
- From: Knute Johnson <nospam@xxxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 28 Aug 2007 14:32:54 -0700
bH wrote:
Hi All,
This program uses the JFileChooser. It works as intended but once the
text is downloaded I cannot get my cursor to move farther down the
text. For that reason, I want to add scroll bars to the text area. I
tried adding this line below in various locations referencing the
fTextArea but that does not work. Obviously I need something more.
"fTextArea.SCROLLBARS_BOTH;"
What am I missing?
Any help is appreciated.
bH
//obtained from:
//http://www.particle.kth.se/~lindsey/JavaCourse/Book/Code/P1/Java/
Chapter09/Choosers/File/FileChooseApp.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
/**
* Demonstrate the use of a JFileChooser to open and
* save files. The chooser filers for *.java files. Opening
* the file results in the text fillig a JTextArea component.
* The text can be modified and saved to a new file.<br><br>
**/
public class FileChooseApp extends JFrame
implements ActionListener
{
JMenuItem fMenuOpen = null;
JMenuItem fMenuSave = null;
JMenuItem fMenuClose = null;
JTextArea fTextArea;
JavaFilter fJavaFilter = new JavaFilter ();
File fFile = new File ("default.java");
/** Create a frame with JTextArea and a menubar
* with a "File" dropdown menu.
**/
FileChooseApp (String title) {
super (title);
Container content_pane = getContentPane ();
// Create a user interface.
content_pane.setLayout ( new BorderLayout () );
fTextArea = new JTextArea ("");
content_pane.add ( fTextArea, "Center");
// Use the helper method makeMenuItem
// for making the menu items and registering
// their listener.
JMenu m = new JMenu ("File");
// Modify task names to something relevant to
// the particular program.
m.add (fMenuOpen = makeMenuItem ("Open"));
m.add (fMenuOpen = makeMenuItem ("Save"));
m.add (fMenuClose = makeMenuItem ("Quit"));
JMenuBar mb = new JMenuBar ();
mb.add (m);
setJMenuBar (mb);
setSize (400,400);
} // ctor
/** Process events from the chooser. **/
public void actionPerformed ( ActionEvent e ) {
boolean status = false;
String command = e.getActionCommand ();
if (command.equals ("Open")) {
// Open a file
status = openFile ();
if (!status)
JOptionPane.showMessageDialog (
null,
"Error opening file!", "File Open Error",
JOptionPane.ERROR_MESSAGE
);
} else if (command.equals ("Save")) {
// Save a file
status = saveFile ();
if (!status)
JOptionPane.showMessageDialog (
null,
"IO error in saving file!!", "File Save Error",
JOptionPane.ERROR_MESSAGE
);
} else if (command.equals ("Quit") ) {
dispose ();
}
} // actionPerformed
/** This "helper method" makes a menu item and then
* registers this object as a listener to it.
**/
private JMenuItem makeMenuItem (String name) {
JMenuItem m = new JMenuItem (name);
m.addActionListener (this);
return m;
} // makeMenuItem
/**
* Use a JFileChooser in Open mode to select files
* to open. Use a filter for FileFilter subclass to select
* for *.java files. If a file is selected then read the
* file and place the string into the textarea.
**/
boolean openFile () {
JFileChooser fc = new JFileChooser ();
fc.setDialogTitle ("Open File");
// Choose only files, not directories
fc.setFileSelectionMode ( JFileChooser.FILES_ONLY);
// Start in current directory
fc.setCurrentDirectory (new File ("."));
// Set filter for Java source files.
fc.setFileFilter (fJavaFilter);
// Now open chooser
int result = fc.showOpenDialog (this);
if (result == JFileChooser.CANCEL_OPTION) {
return true;
} else if (result == JFileChooser.APPROVE_OPTION) {
fFile = fc.getSelectedFile ();
// Invoke the readFile method in this class
String file_string = readFile (fFile);
if (file_string != null)
fTextArea.setText (file_string);
else
return false;
} else {
return false;
}
return true;
} // openFile
/**
* Use a JFileChooser in Save mode to select files
* to open. Use a filter for FileFilter subclass to select
* for "*.java" files. If a file is selected, then write the
* the string from the textarea into it.
**/
boolean saveFile () {
File file = null;
JFileChooser fc = new JFileChooser ();
// Start in current directory
fc.setCurrentDirectory (new File ("."));
// Set filter for Java source files.
fc.setFileFilter (fJavaFilter);
// Set to a default name for save.
fc.setSelectedFile (fFile);
// Open chooser dialog
int result = fc.showSaveDialog (this);
if (result == JFileChooser.CANCEL_OPTION) {
return true;
} else if (result == JFileChooser.APPROVE_OPTION) {
fFile = fc.getSelectedFile ();
if (fFile.exists ()) {
int response = JOptionPane.showConfirmDialog (null,
"Overwrite existing file?","Confirm Overwrite",
JOptionPane.OK_CANCEL_OPTION,
JOptionPane.QUESTION_MESSAGE);
if (response == JOptionPane.CANCEL_OPTION) return false;
}
return writeFile (fFile, fTextArea.getText ());
} else {
return false;
}
} // saveFile
/** Use a BufferedReader wrapped around a FileReader to read
* the text data from the given file.
**/
public String readFile (File file) {
StringBuffer fileBuffer;
String fileString=null;
String line;
try {
FileReader in = new FileReader (file);
BufferedReader dis = new BufferedReader (in);
fileBuffer = new StringBuffer () ;
while ((line = dis.readLine ()) != null) {
fileBuffer.append (line + "\n");
}
in.close ();
fileString = fileBuffer.toString ();
}
catch (IOException e ) {
return null;
}
return fileString;
} // readFile
/**
* Use a PrintWriter wrapped around a BufferedWriter, which in turn
* is wrapped around a FileWriter, to write the string data to the
* given file.
**/
public static boolean writeFile (File file, String dataString) {
try {
PrintWriter out =
new PrintWriter (new BufferedWriter (new FileWriter (file)));
out.print (dataString);
out.flush ();
out.close ();
}
catch (IOException e) {
return false;
}
return true;
} // writeFile
/** Create the framed application and show it. **/
public static void main (String [] args) {
// Can pass frame title in command line arguments
String title="Frame Test";
if (args.length != 0) title = args[0];
FileChooseApp f = new FileChooseApp (title);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setVisible (true);
} // main
}// class FileChooseApp
// JavaFilter class
import javax.swing.*;
import java.io.*;
/** Filter to work with JFileChooser to select java file types. **/
public class JavaFilter extends javax.swing.filechooser.FileFilter
{
public boolean accept (File f) {
return f.getName ().toLowerCase ().endsWith (".java")
|| f.isDirectory ();
}
public String getDescription () {
return "Java files (*.java)";
}
} // class JavaFilter
Look at JScrollPane.
--
Knute Johnson
email s/nospam/knute/
.
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- Adding SCROLLBARS to a JTextArea
- From: bH
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