Lab 5: OO Design & Java

OO Design
1. Discuss how to design a class for a Circle and an Ellipse.
2. Discuss how to design a class for a TextDoc and a HTMLDoc.
Emacs
1. Download my .emacs example.
2. Merge with your ~/.emacs. Enjoy coding, debugging, and even reading email from emacs.

Java

How to compile a Java program?
1. Create a sample program called Integer2Int.java using your favorite editor as below:
```
public class Integer2Int {
    public static void main(String[] args) {
        Integer i = new Integer(1);
        System.out.println(i.intValue());
    }
}
    
```
2. The Java compiler is located at /usr/csshare/bin/javac. So, add the path /usr/csshare/bin to your PATH environment variable if you haven't done so.
3. To compile Integer2Int.java, run:
```
$ javac Integer2Int.java
    
```
4. To run the Java code, run:
```
$ java Integer2Int
    
```
5. Alternatively, not recommended for this course, you could use gcj to compile the Java into a native executable.
```
$ gcj --main=Integer2Int Integer2Int.java -o Integer2Int
$ Integer2Int
    
```

I/O

ConsoleIO.java

import java.io.Console;

class ConsoleIO {
    public static void main(String[] args) {
	Console c = System.console();
	if (c == null) {
            System.err.println("No console!");
            System.exit(-1);
        }
	String login = c.readLine("Login: ");
	char[] passwd = c.readPassword("Password: ");
	c.format("Login: [%s]\n", login);
	//System.out.println("Login: " + login);
	c.format("Password: ");
	for (int i = 0; i < passwd.length; i++) {
	    c.format("%c", passwd[i]);
	}
	c.format("\n");
    }
}

FileIO.java

import java.io.*;

class FileIO {
    public static void main(String[] args) {
	try {
	    BufferedReader fp = new BufferedReader(new FileReader(args[0]));
	    for (String line = fp.readLine();
		 line != null;
		 line = fp.readLine()) {
		System.out.println(line);
	    }
	    fp.close();
	} catch ( Exception e ) {
	    System.out.println(e);
	}
    }
}

ReadInt.java

import java.io.*;
import java.util.*;

class ReadInt {
    public static void main(String args[]) {
	try {
	    BufferedReader fp = new BufferedReader(new FileReader(args[0]));
	    for (String line = fp.readLine();
		 line != null;
		 line = fp.readLine()) {
		StringTokenizer st = new StringTokenizer(line, " ");
		int x = Integer.parseInt(st.nextToken());
		int y = Integer.parseInt(st.nextToken());
		System.out.format("(%d, %d)\n", x, y);
	    }
	    fp.close();
	} catch (Exception e) {
	    System.out.println(e);
	}
    }
}

Arrays

Echo.java

class Echo {
    public static void main (String[] args) {
        for (int i = 0; i < args.length; i++)
            System.out.println(args[i]);
    }
}

Arrays.java

class Arrays {
    public static void main(String[] args) {
	// http://java.sun.com/docs/books/jls/second_edition/html/arrays.doc.html
	int[] factorial = { 1, 1, 2, 6, 24, 120, 720, 5040 };
	char ac[] = { 'n', 'o', 't', ' ',
		      'a', ' ',
		      'S', 't', 'r', 'i', 'n', 'g' };
	String[] aas = { "array", "of", "String", };
	Exception ae[] = new Exception[3]; 
	Object aao[][] = new Exception[2][3];

	for (int i = 0; i < ac.length; i++) {
	    System.out.print(ac[i]);
	}
	System.out.println();
    }
}

Swing

HelloWorldSwing.java

// Modified from http://java.sun.com/docs/books/tutorial/uiswing/examples/start/HelloWorldSwingProject/src/start//HelloWorldSwing.java

import javax.swing.*;        

public class HelloWorldSwing {
    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
	//Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("HelloWorldSwing");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Add the ubiquitous "Hello World" label.
        JLabel label = new JLabel("Hello World");
        frame.getContentPane().add(label);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Menu.java

// Modified from: http://zerioh.tripod.com/ressources/menu.html

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

public class Menu extends JFrame {
    public Menu() {
	super("Menu Demo for CS181");
        
	// Close the window properly
	setDefaultCloseOperation(EXIT_ON_CLOSE);

	// Add menu and menu items
	JMenu file = new JMenu("File");
	file.setMnemonic('F');
	JMenuItem newItem = new JMenuItem("New");
	newItem.setMnemonic('N');
	file.add(newItem);
	JMenuItem openItem = new JMenuItem("Open");
	openItem.setMnemonic('O');
	file.add(openItem);	
	JMenuItem exitItem = new JMenuItem("Exit");
	exitItem.setMnemonic('x');
	file.add(exitItem);
	
	// Add an action listener to exit item
	exitItem.addActionListener(
	    new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		    JOptionPane.showMessageDialog(null, "Exit is pressed");
		}
	    }
	    );

	// Add a menu bar
	JMenuBar bar = new JMenuBar();
	setJMenuBar(bar);
	bar.add(file);
	
	// Show the frame
	setLocation(50, 50);
	setSize(300, 200);
	setVisible(true);
    }
    public static void main(String[] args) {
	// Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);
	new Menu();
    }
}

Lab 5: OO Design & Java

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