Reading from a text file, then writing back to Text Area in Reverse

[medic642]

Hello,

I am working on a school assignment (GUI based) that will read an existing file consisting of single words on six different lines, then write these words in reverse order to a JTextArea. I am having trouble locating any guides to help me through the creation of an array and then reading from the array in reverse order. I have looked at creating a buffer and reading from it at specific points to get the characters but it seems there should be a better way with an array. Does anyone have any suggestions for sites to look at? The API pages are cryptic and give no examples. I have already created my GUI and have a fileinputstream working.

Thanks!

Jared

[sunde887]

What have you tried? Have you read the file into an array?(or the easier to work with ArrayList). Once you do that a simple loop can be used to build the string from the array or list.

[medic642]

Actually, I am trying to work through this myself and I am looking for good documentation of array or arraylist with examples. Once I get a good grip on the concept I think I can work through it myself. I just can't find documentation with examples!

Thank you.

[Norm]

Go to this site and Search for array:
The Really Big Index

[sunde887]

Here is a link to the tutorials on arrays: Arrays (The Java™ Tutorials > Learning the Java Language > Language Basics)

You can find a similar one for collections on the same site.

Edit: too slow :(

[Junky]

This can be achieved with recursion but I guess you haven't covered that yet.

[medic642]

Ok, Here's the code I have so far. Won't compile and I need a few pointers, please. I am getting errors about the textcopyarea and I need to now how to tweak the code to get my file "input.txt" as the input file Thanks!

// Import Classes

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JCheckBox;
import javax.swing.JTextArea;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;


public class FileToArray extends JFrame
{


public static void main(String[] args) {

// Create Window

JFrame frame = new JFrame();

frame.setSize(400, 250);
frame.setTitle("File Reader");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

// Create Text Area

final JTextArea textcopyarea = new JTextArea(10, 20);
textcopyarea.setText("");

// Create Button

JButton button = new JButton("Process");

// Create Display Panel

JPanel panel = new JPanel();

panel.add(button);
panel.add(textcopyarea);
frame.add(panel);

// Listener Class

class CalculateListener implements ActionListener
{

public void actionPerformed(ActionEvent event) {


// Get Input From File

try {
String brline="";
String filebuffer[]=new String[100000];
int i=0; int j=0;
RandomAccessFile file=new RandomAccessFile(filenametext.getText(),"r");
while((brline = file.readLine()) != null)
{
filebuffer[i]=brline;
i++;
}
int len = i;
file.close();

txtcopyarea.append("\r\n");
for(j = len; j>=0 ;j--)
{
txtcopyarea.append(filebuffer[j]);
txtcopyarea.append("\r\n");
txtcopyarea.setLineWrap(true);
txtcopyarea.setWrapStyleWord(false);
txtcopyarea.setCaretPosition(txtcopyarea.getText() .length() - 1);
}

}catch(Exception e) { System.out.println(e); }


}
}

ActionListener listener = new CalculateListener();
button.addActionListener(listener);

frame.setVisible(true);

    }


}

[sunde887]

First thing I see is that you are importing nio classes, this can all be done with regular io(and probably should), nio is probably too advanced for you.

I would also suggest you not clump all code into the main method and instead have the main method only contain a line or two of code.

Why are you using random access file? Do you need to access into the file randomly? If not, use File.

All you need for io: http://download.oracle.com/javase/tu.../essential/io/

And for swing: http://download.oracle.com/javase/tu...ing/index.html

[Norm]

I am getting errors about the textcopyarea

When you get errors, please copy and paste the full text of the message.

For reading the file, the Scanner class is much simpler.