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 + ""); 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);