Java JTextArea class

Java Swing Tutorial Explaining the JTextArea Component. JTextArea allows editing of multiple lines of text. JTextArea can be used in conjunction with class JScrollPane to achieve scrolling. The underlying JScrollPane can be forced to always or never have either the vertical or horizontal scrollbar.

JTextArea Source Code

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

public class JTextAreaDemo extends JFrame implements ActionListener {

	JTextField jtfInput;
	JTextArea jtAreaOutput;
	String newline = "\n";
	public JTextAreaDemo() {
		createGui();
	}
	public void createGui() {
		jtfInput = new JTextField(20);
		jtfInput.addActionListener(this);
		jtAreaOutput = new JTextArea(5, 20);
		jtAreaOutput.setCaretPosition(jtAreaOutput.getDocument()
				.getLength());
		jtAreaOutput.setEditable(false);
		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