DisplayString

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;

public class DisplayString extends JPanel implements ActionListener
{
	//Static/Final Variables
	private static final long serialVersionUID = 1L;
	private static final int WIDTH = 640;
	private static final int HEIGHT = 480;

	//Instance Variables
	private JButton submit;
	private JTextArea result;
	private JTextArea sentence;

	//Main
	public static void main(String args[])
	{
		//Create Frame and assign values.
		JFrame frame = new JFrame("Displaying String in Uppercase and Lowercase");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLayout(null);
		frame.setContentPane(new DisplayString());
		frame.setSize(WIDTH, HEIGHT);
		frame.setResizable(false);
		frame.setVisible(true);
	}

	//Constructor
	public DisplayString()
	{
		init();
		add();
	}

	//Initialization
	public void init()
	{
		//Variable Initialization
		submit = new JButton("Submit");
		submit.setBounds(16, 400, WIDTH-40, 40);
		submit.addActionListener(this);

		result = new JTextArea();
		result.setBorder(BorderFactory.createLineBorder(Color.GRAY));
		result.setEditable(false);
		result.setOpaque(true);
		result.setBackground(Color.WHITE);
		result.setBounds(16, 96, WIDTH-40, HEIGHT-(96*2));

		sentence = new JTextArea();
		sentence.setBorder(BorderFactory.createLineBorder(Color.BLACK));
		sentence.setOpaque(true);
		sentence.setBackground(Color.WHITE);
		sentence.setBounds(16, 16, WIDTH-40, 64);

		//JPane Settings
		setLayout(null);
		setBackground(Color.LIGHT_GRAY);
	}

	//Add in buttons to the frame.
	public void add()
	{
		add(submit);
		add(result);
		add(sentence);
	}

	//When an action is performed.
	@Override
	public void actionPerformed(ActionEvent e)
	{
		//If the submit button is clicked.
		if (e.getSource() == submit)
		{
			displayString();
		}
	}

	//Displays the string in the text box on the JLabel
	public void displayString()
	{
		//Variables
		String str = sentence.getText();

		//Clear the text field
		sentence.setText("");

		//Add the upper and lowercase strings to the JLabel
		result.setText(String.format("%s%n%n%s%n%n", str.toUpperCase(), str.toLowerCase()));
	}

}