Exercise 1 : Some revisions on Java and rediscovery of Swing 'Hello World'

You will improve the following very simple example by making some modifications.

/** Simple Java 2D Example
 *
 *	@version 0.9  12/07/2001
 *	@author Pascal Vuylsteker
 */
 

import javax.swing.*;
 

public class HelloWordSimple
{	public static void main(String[] args)
	{	HelloWordFrame frame = new HelloWordFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.show();
	}
}


class HelloWordFrame extends JFrame 
{	public HelloWordFrame()
	{	setTitle("Hello World !! ");
		setSize(300,200);
		
		HelloPanel panel = new HelloPanel();
		Container contentPane = getContentPane();
		contentPane.add(panel);
	}
}

class HelloPanel extends JPanel
{	public void paintComponent(Graphics g)
	{	super.paintComponent(g);
		g.drawString("Hello again...", 20, 20);
	}
}

Understand how that program works.

Add some comments in the code

Debug it... because it is the more time consuming activity in computing.

import java.awt.*;

Transform that program into a two Class program (instead of three - HelloWordSimple, HelloWordFrame and    HelloPanel)

Set the background of the frame to be cyan.

Set the size of the window by using 'command line' parameters. Try it and then come back to class fields.

Add some comments in the code

Make the program find the size of your computer screen, in order to make the frame half that size, and centre it in the middle of the screen.

Tip : Explore the Toolkit Class

Make the window not resizable.

Add some comments in the code

Get a pop up window that asks for your name, before showing up the "hello world" frame.

showInputDialog from JOptionPane...

String name = JOptionPane.showInputDialog("What is your Name");

Place text in the HelloWord Panel such that the end of the text is one third of the distance from the right and the bottom of the window. That text will be "Bonjour xxxx", where xxxx is the name entered in the inputDialog.

use a Font object, get a FontMetrics from it, and then get the stringWidth or...
use a Font object, a Graphics2D object (from the Graphics one), and a FontRenderContext and 'getStringBounds' from the font

Check that there are enough comments in your code and run javadoc to see the result.

Think about using some of javadoc options in order to get more information (-private, -author, etc)

Put your class in a package and use it in another short program from another directory.

package
import
javac -d
CLASSPATH
package name : reversed internet domain name

Extra :

List of the fonts available in your java package.

Table of character entities.