INFORMATION & COMPUTER SCIENCE DEPARTMENT, KFUPM

ICS – 102 SECTION 65  (002 Semester)

INTRODUCTION TO COMPUTING

LAB  #00 Introduction to the Programming Environment

 

Instructor: Bashir M. Ghandi

 

Objectives:

• Understand/Review how to work with Windows GUI environment
• Review some essential DOS Commands
• Learn how to install and Use JDK to compile Applications and Applets
• Learn how to use JCreator, an IDE for Java programming

 

1.  Introduction to Windows

Windows (98, NT or, 2000) is an example of an operating system.  The operating system is the first piece of software loaded into memory when a computer starts. It is the operating system that launches/starts other software programs such as word processors, web browsers, etc. The operating system manages all of the resources on the computer; it controls the mouse, the monitor, the printer, etc.

The following shows a condensed version of the Windows NT desktop (Windows 98 is similar). These objects may appear anywhere on the screen.

On windows, commands are represented by means on menus options, buttons or icons.  To execute a command, we single click the left mouse button while pointing to its menu or button option; or double click its corresponding icon.

1.1  Using the Notepad:

Notepad is an application that comes with window that can be used to type text.

Start Notepad by following the sequence:   Start àPrograms àAccessories àNotepad

 

 

Type the following sample program exactly as it is shown on the figure below.

Just type the characters in. You can move around the text using the mouse or arrow keys. To delete mistakes, use the "backspace" key or the "delete" key. To start a new line, just hit "Enter". In typing in the program, you DO have to get upper and lower case letters, and all punctuation exactly correct. You do not have to get the spaces exactly correct.

1.2  Saving the Source File

To save the file follow the following steps:

·         Move the mouse pointer to "File" and click on it. You will get a sub-menu. Now click on "Save As".

·         In the window that appears, use the arrow on the right of the “Save in” box to change the drive to D: and the folder to Workarea

• In the “File name” box type: Hello.java
• Clicking on the arrow to the right of “Save as type” box  and select "All Files".
• If you get exactly the following figure, Click on "Save" 

 

After saving the file, minimize the Notepad window by clicking the minimize button at the top right corner.  This should minimize the window to an icon on the Task bar.

1.3  Managing files .

 

In addition to providing menus and icons for loading programs, the Windows operating system also provides facilities for managing user files (creating folders, copying files, deleting files, etc.).

The easiest way to manage files is to use the “My Computer” icon  (see above).

 

Double click on my computer.  This display the disk drives accessible to you. 

Click on drive D:  and click on the folder Workarea to displays the list of files it contains.  You should see the Hello.java file listed.

 

You can copy the file Hello.java to your floppy by pointing to it and clicking the right mouse button.

This should open a menu from which you can choose “Send To” followed by “3½ Fllopy (A)” to save your file on drive A (the floppy).

 

You can also copy a file from any folder to any other folder by  simple“drag and drop” process.

 

Drag and drop means point to a file you wish to copy and click it without releasing your finger.  Then move the mouse to the folder you wish to copy the file while still pressing the mouse button, when you reach the folder, release the button. 

 

To practice this, first let us create a folder “LAB1” under Workarea. 

To do this, while in the Workarea, follow the command sequence: File à NewàFolder and type LAB1 as the name of your folder.

 

Now click and drag Hello.java file to Lab1 folder.  This should move the file to Lab1 folder.  Double click on the folder to view the file.

 

Now how do we copy the file back to Workarea folder or to another folder on a different drive?

To do this, we need to double click on My Computer to open another window and open the folder we wish to copy to.

We then drag the file from the other window to the new window.

 

Note:

You can use the button, to go back to the previous folder.

You can select all files in a given folder by pressing A while holding the Ctrl key (Ctrl+A)

You can select adjacent set of files by selecting the first and then selecting the last while pressing the Shift key.

You can select any set of files by clicking them individually while holding the Ctrl key.

To delete a file or group of files, simply select the file (or group of files) and press the Delete Key.

Windows allow more than one application to be running at the same time.  All active applications are shown on the Task bar.  To switch to Notepad for example, simply click on its icon on the task bar.

 

1.4   Formatting a diskette.

When you buy a new diskette, you may need to format it before you store files on it.

To do this, insert the diskette in the floppy drive and double click on My Computer to display list of drives.  Right click on drive A.  This should open a menu from which you select “Format” to format your diskette.

2.         Some Essential DOS Commands

DOS stands for Disk Operating System.  It is a command based operating systems (OS) used on PC prior to Windows.  Although the OS has changed, DOS commands are still supported by these new OSs. 

 

To be able to use JDK effectively, you need to know some basic DOS commands.  To do this, first you need to switch to DOS environment, also called, Command Prompt.

 

You can switch to the DOS command by locating its menu option on the Windows program menu system.

You may find it the JDK sub-menu.

Clicking this should take you to the command prompt which may look like the following figure:

 

2.1  Changing Drives:

To change to a particular drive, type the drive letter followed by colon and press enter. (e.g.  A:  )

If you are not already on drive D:  change your drive to D.  If you are already on D, change to another drive and then change back to D.

 

2.2  Changing folders.

The cd command is used to change folder.  You need to give it the folder you wish to change to, as a parameter.

Examples are:

 

cd \                                          This changes to the root folder (top most folder) of the current drive.

cd workarea                          This changes to the workarea folder which is under the root folder

cd Lab1                                  This changes to the lab1 folder which is uder the workarea folder.

cd ..                                         This changes to a folder one step back.

 

Note that you cannot randomly change from one folder to another.  You need to either follow them in sequence or give the full path as your parameter.  For example, if you are at the root folder of drive D, then the command

cd Lab1

 will not work.

You have to either follow the sequence:

cd workarea

cd Lab1

Or you have to type:

cd workarea\lab1

 

2.3  Displaying list of files

The dir command is used to display the list of files in a given folder.  Change to the workarea folder and type dir followed by enter.  You should see a list like the following.

 

The list indicates the files and folders in the current folder along with the date and time they were created or last modified followed by their size in bytes (for files) or <DIR> to indicate folders.

2.4  Loading a Program

To load a program in DOS, we simply type the program name and press the Enter Key.  For example, to load Notepad program, type Notepad and press enter.

 

Note: For the above to work, the program must be either in the current folder, or in a list of folders specified for the operating system to search for applications, using the PATH command.  We shall discuss the path command when discussing JDK below.

2.5  Exiting from DOS

The EXIT command is used to exit from the DOS environment back to windows.

 

 

3.  Installing and using JDK

3.1  Obtaining JDK

If you need to install JDK on your personal machine, you can borrow a CD containing the latest version of JDK (1.3) from me.   The CD also contains our lecture slide, some on-line Java books and other utilities.

 

Alternatively, you can download JDK from Sun Microsystem free of charge on their internet site: http://java.sun.com/j2se/1.3/

 Make sure you download the Microsoft Windows version.  Also remember to download the documentation as well as HTML converter.  All these are included on the CD.

 

3.2  Installing JDK 1.3

To install JDK, simply double click on the file:  j2sdk1_3_0-win-i.exe and follow the instruction that follows.

It will automatically suggest installing on a folder  JDK1.3 on one of your drives as shown below:

 

I suggest you use the Browse button to change this option to something like

D:\Java\JDK

This is a good Idea if you wish to group other Java related applications together.

 

After the Installation, a directory structure similar to the following will be created:

 

The bin folder is the most important among the folders above.  It contains among others, the compiler, javac.exe, the Interpreter, java.exe and the Applet viewer, Appletviewer.exe.

 

Now recall from our discussion on DOS that for a program to be executed, it must be either in the current folder or it must me in the list of folders specified for the operating system to search, using the PATH command.

 

Since we would like to be able to execute the Java tools from any folder, we need to add the folder D:\java\jdk\bin to the list of folders that Windows OS should search.  Assuming the above is where JDK is installed, the command to do this is:

 

PATH = D:\java\jdk\bin;%path%

 

If you are using windows, it is better to add this in your AUTOEXEC.BAT so that it is executed automatically each time your computer starts, otherwise, you need to execute this each time you need use JDK tools.

 

3.3  Compiling and Running Java Application.

Running a Java source code (.java) involves two steps:

First, the source file in converted to a bytecode (.class) using the compiler, javac.exe

Secondly, the interpreter, java.exe is used to execute the application.

To practice this,

Change to DOS command prompt and change your drive/folder to D:\workarea

Type DIR and press enter to make sure that the file Hello.java is there.

 

Now type the following command to compile the program:

javac Hello.java

 

Note that the case (capital/small letter) is very important to both the compiler and the interpreter.

Type DIR and press enter to see what happened.  Another file Hello.class is created.

 

Now excute the program by typing

java Hello

 

Note:  DO NOT type  java Hello.class

You should get the following output.

 

3.4  Compiling and Running Java Applets

A Java Applet is a java program that is designed to run on a Web page.  We shall learn more about applets in lab 4 and 5.  For now, what we need to know is how to compile and run an applet.

 

Type the following code using Notepad and save is as HelloApplet.java.  You can also get it from my computer or my homepage

If your are viewing this from my home page, right click here to download the file.

.

import java.applet.Applet;

import java.awt.Graphics;

 

class HelloApplet extends Applet {

    public void paint(Graphics g) {

        g.drawString("Hello world!", 50, 25);

    }

}

 

Compile this program as we did before using javac.exe

Now one difference between an applet and an application is that it cannot be executed by the interpreter as it does not have the main method.  To execute an applet, we need to call it from a HTML file. 

 

Type the following html file using notepad and save it as HelloApplet.html or copy it from my computer or my homepage.

If your are viewing this from my home page, right click here to download the file.

<HTML>

<HEAD>

<TITLE> A Simple Program </TITLE>

</HEAD>

<BODY>

<APPLET CODE="HelloApplet.class" WIDTH=150 HEIGHT=40>

</APPLET>

</BODY>

</HTML>

 

Now exit to Windows and use my computer to locate the HelloApplet.html and double click it.  It should display your applet on your browser.

 

4.  Introduction to JCreator

JCreator is one of the many Integrated Development Environments (IDEs) that are available for developing java applications and applets.

An IDE is a program which can be used to edit/type, compile, and execute programs all in the same place.

JCreator is available free at the following internet site:  www.jcreator.com

Of course it is also included on the CD.

We shall be using JCreator for the exercises in this lab.

It has many useful features such as Syntax coloring, auto indent, etc.

Locate the JCreator menu option and start it. 

Compiling and executing an Application using JCreator

Use the File àOpen menu and locate and open the Hello.java file from the file system.

Compile the Hello.java file by using the Build à Compile File menu, or by clicking the compile button   

You should get a message at the bottom saying Process Completed.

Now execute the program by using the Build àExecute File menu, or by clicking the execute button    

You should get the output displayed.

Compiling and executing Applets using JCreator.

The process compiling an applet is the same as compiling an application.  However, executing it requires creating a HTLM file.  JCreator can be used to create both Java source files and HTML files.  It can also be used to create ordinary text files.

Open the HelloApplet.java and HelloApplet.html files, compile the java files and switch to the HTML file and execute it.  It should display the applet using the applet viewer.