JScrollPane scrollPane = new JScrollPane(jtAreaOutput,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
GridBagLayout gridBag = new GridBagLayout();
Container contentPane = getContentPane();
contentPane.setLayout(gridBag);
GridBagConstraints gridCons1 = new GridBagConstraints();
gridCons1.gridwidth = GridBagConstraints.REMAINDER;
gridCons1.fill = GridBagConstraints.HORIZONTAL;
contentPane.add(jtfInput, gridCons1);
GridBagConstraints gridCons2 = new GridBagConstraints();
gridCons2.weightx = 1.0;
gridCons2.weighty = 1.0;
contentPane.add(scrollPane, gridCons2);
}
public void actionPerformed(ActionEvent evt) {
String text = jtfInput.getText();
jtAreaOutput.append(text + newline);
jtfInput.selectAll();
}
public static void main(String[] args) {
JTextAreaDemo jtfTfDemo = new JTextAreaDemo();
jtfTfDemo.pack();
jtfTfDemo.addWindowListener(new WindowAdapter() {

                                    public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
jtfTfDemo.setVisible(true);
}
}

Output: