How do I send data from a method in DATA class to a jTextArea in guiTest class

How do I send data from the method in Data class to a JTextArea in GUITest class, or System.out.println redirected to the JTextArea?

I need to do it in a way that only when data in DataOut method is updated, its sent, not polled for new data from the main method.

This is the sample code

    public class GUITest 

	private JFrame frame;
 	JTextArea textArea_1 = new JTextArea();
	
	public static void main(String[] args) throws InterruptedException, IOException {
		
		System.out.println ("Thread Name 0 "+ Thread.currentThread().getName());
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				try {
					GUITest window = new GUITest();
					window.frame.setVisible(true);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
		
		Data data = new Data();
		
		for(int i = 0; i < 100; i++) {
			Thread.sleep(20);
			data.DataOut();
		}
	}

	public GUITest() throws IOException {
	
		initialize();
	}
		
	public  void initialize() throws IOException {
		frame = new JFrame();
		frame.setBounds(1200, 100, 450, 300);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.getContentPane().setLayout(null);
		
		textArea_1.setBounds(120, 45, 100, 23);
		textArea_1.setText("");
		frame.getContentPane().add(textArea_1);
	}
}

    import java.io.IOException;

    public class Data {

	public void DataOut() throws IOException {
		int S = 0;
		for(int i = 0; i < 20; i++) {
			S++;
		}
		System.out.println(S);  // This should print to the JTextArea of class GUITest
	}
}

There are multiple ways to do that. The first thing that comes in my mind is:

Let the Data class constructor accept an istance of GUITest, so it becomes:

Data data = new Data(this);

and Data becomes:

public class Data{
  GUITest istance;

  public Data(GUITest istance){
     this.istance=istance;
  }
}

Then, create a method in GUITest called setTextAreaMessage(String message) and in the Data class, instead of System.out.println(S); you call istance.setTextAreaMessage(S);
Don't forget to set the text inside the setTextAreaMessage(String message) method with the line text_Area1.setText(message);

This solution works, but honestly I don't remember if you can declare a widget like jTextArea as static. If you can, you can just do something like GUITest.text_Area1.setText(S);