Adding JTextArea to JFrame - swing

Question

If I have 1 main class and 2 subclasses
subclass 1: public class JPanel1 extends JPanel {....properly initialized}
subclass 2: public class JTextArea1 extends JTextArea {... properly initialized}
Why can I do jframe1.add(new JPanel1()) but not jframe1.add(new JTextArea1())? for a properly initialized JFrame jframe1 = new JFrame();?
My goal is to output data into both the jpanel and the jtextarea

Answer 1

Here on my side, the issue you raising, is working fine. Do let me know, if you think, this is not what you mean :-)
import java.awt.*;
import javax.swing.*;
public class SwingExample
{
private CustomPanel customPanel;
private CustomTextArea customTextArea;
private void displayGUI()
{
JFrame frame = new JFrame("Swing Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel contentPane = new JPanel();
contentPane.setLayout(new BorderLayout(5, 5));
contentPane.setBorder(
BorderFactory.createLineBorder(
Color.DARK_GRAY, 5));
customPanel = new CustomPanel();
customTextArea = new CustomTextArea();
contentPane.add(customPanel, BorderLayout.CENTER);
contentPane.add(customTextArea, BorderLayout.LINE_START);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args)
{
Runnable runnable = new Runnable()
{
#Override
public void run()
{
new SwingExample().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
class CustomPanel extends JPanel
{
private static final int GAP = 5;
public CustomPanel()
{
setOpaque(true);
setBackground(Color.WHITE);
setBorder(BorderFactory.createLineBorder(
Color.BLUE, GAP, true));
}
#Override
public Dimension getPreferredSize()
{
return (new Dimension(300, 300));
}
}
class CustomTextArea extends JTextArea
{
private static final int GAP = 5;
public CustomTextArea()
{
setBorder(BorderFactory.createLineBorder(
Color.RED, GAP, true));
}
#Override
public Dimension getPreferredSize()
{
return (new Dimension(100, 30));
}
}
OUTPUT :