Thread: Output in JTextFiled with refreshing every row

I am a beginner in Java and had started writing a program to read text from a file and want to output each row to JTextField.
I want to compare each row of number so I need a field where each row of data keeps refreshing.
I can do it with Visual Basic with loop, Me.refresh, and system.thread.sleep. But I need to achieve it with Java.

I use System.out.println(num); which showed all rows of the file.

When I use textArea.append(num + "\n"); to output it, I only got all rows displayed after it reached the end. (textArea = new JTextArea("",10,30);

If I use dataRead.setText(num); to output it, I only got the last row displayed after it reached the end. dataRead = new JTextField(7);

Can anyone help?

Confused as to whether you're using a JTextField or a JTextArea. Show the code (as little as possible) that isn't performing as desired and describe current and desired behavior. If showing a little code and describing a lot is too hard, then provide a short, simple example of code that demonstrates the current behavior with a description of what you'd like it to be.

Hi Greg

Please find my code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
import java.io.*;

public class FileInputDemo extends JFrame
implements ActionListener {

private JTextArea textArea;
private JButton openButton;
private JTextField nameField;
private JTextField dataRead;
private JLabel nameLabel;

public static void main (String [] args) {
FileInputDemo frame = new FileInputDemo();

frame.setSize(400, 300);
frame.createGUI();
frame.setVisible(true);
}


private void createGUI() {
setDefaultCloseOperation(EXIT_ON_CLOSE);
Container window = getContentPane();
window.setLayout(new FlowLayout());

nameLabel = new JLabel("File name: ");
window.add(nameLabel);

nameField = new JTextField("C:\\Data.txt", 10);
window.add(nameField);
nameField.addActionListener(this);

dataRead = new JTextField(7);
window.add(dataRead);

textArea = new JTextArea("",10,30);
JScrollPane scrollPane = new JScrollPane(textArea);
window.add(scrollPane);

openButton = new JButton("open");
window.add(openButton);
openButton.addActionListener(this);
}

public void actionPerformed(ActionEvent event) {
java.io.File file = new java.io.File("C:\\Data.txt");
if (event.getSource() == openButton) {
try {
Scanner input = new Scanner(file);
do {
String num = input.next();
dataRead.setText(num);
} while (input.hasNext());

input.close();
}
catch (FileNotFoundException e) {
System.err.format("File does not exist");
}
}
}
}

--- Update ---

Hi Greg

Thank you for your help.
What I want to do is to read data from a data.txt file which contains one column of numbers with many rows.
such as:
23456
23458
23460
23455 and so on.
I want these rows of numbers to be displayed in a JTextField one by one so I can compare each row with a target number.
Please find below my program which have both a JTextField and a JTextArea and you may run to see.

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
 
/**
 *
 * @author Ken
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*; 
import java.io.*;
 
public class FileInputDemo extends JFrame
    implements  ActionListener {
 
    private JTextArea textArea;
    private JButton openButton;
    private JTextField nameField;
    private JTextField dataRead;
    private JLabel nameLabel;
 
    public static void main (String [] args) {
        FileInputDemo frame = new FileInputDemo();
 
        frame.setSize(400, 300);
        frame.createGUI();
        frame.setVisible(true);
    }
 
 
    private void createGUI() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        Container window = getContentPane();
        window.setLayout(new FlowLayout());
 
        nameLabel = new JLabel("File name:  ");
        window.add(nameLabel);
 
        nameField = new JTextField("C:\\Data.txt", 10);
        window.add(nameField);
        nameField.addActionListener(this);
 
        dataRead = new JTextField(7);
        window.add(dataRead);
 
        textArea = new JTextArea("",10,30);
        JScrollPane scrollPane = new JScrollPane(textArea);
        window.add(scrollPane);
 
        openButton = new JButton("open");
        window.add(openButton);
        openButton.addActionListener(this);
    }
 
    public void actionPerformed(ActionEvent event) {
        java.io.File file = new java.io.File("C:\\Data.txt");
	if (event.getSource() == openButton) {
             try {
			Scanner input = new Scanner(file);
			do {
                            String num = input.next();
                            dataRead.setText(num);
                            textArea.append(num + "\n");
                            } while (input.hasNext());
 
                        input.close();
		}
		catch (FileNotFoundException e) {
			System.err.format("File does not exist");
		} 
            }
        }
   }