Studio II.5 Introduction to Java

Authored by Dr. Lester Yee

In order to begin development with Java, one needs to download and configure an appropriate version of a Java Development Kit (JDK) and install it on your system.  The following document details the steps necessary to install Sun’s J2SE JDK v1.3.0 and its corresponding documentation.  Instructions for the Sun Java Servlet Development Kit (JSDK) version 2.1 is also presented for web-based applications development. 

There are numerous Integrated Development Environments (IDE’s) (commercial and otherwise) for Java development available to facilitate code writing.  However, a simple text editor (TextPad v4.4.1 – www.textpad.com) with Java support will be the recommended IDE for this introduction to Java.  TextPad’s simplicity, low learning curve, and small memory footprint makes it an ideal choice to get started in Java programming.

Installing the Sun's J2SE v1.3.0 JDK

Download the Sun J2SE v1.3.0 JDK and its documentation from the following site and install both of them.

 http://www.javasoft.com/j2se/1.3/

 The files to download are:

2sdk-1_3_0-win.exe                            (Install on C: drive)

j2sdk-1_3_0-doc.zip                             (Unzip to C:\)

Figure 1.  Options to check for installing the JDK

Important Note: Modify your autoexec.batfile to include the following environment variable settings:

set PATH=%PATH%;c:\jdk1.3\bin       (where %PATH% is your original path)

set CLASSPATH=.;c:\jdk1.3\lib\tools.jar;c:\jsdk2.1\servlet.jar

Installing the Sun's JSDK v2.1

Download the Sun JSDK v2.1 from the following URL: 

http://www.javasoft.com/products/servlet/archive.html

The file to download are:

jsdk2_1-win.zip                     (Install on C: drive)

Important Note: Modify your autoexec.batfile to include the following environment variable settings:

set CLASSPATH=.;c:\jdk1.3\lib\tools.jar;c:\jsdk2.1\servlet.jar

Installing TextPad v4.4.1

Download a simple yet powerful text editor that has support for Java.  Note that this is a shareware/trial edition.

http://www.textpad.com/

The file to download are:

                txpeng441.exe

When installing choose all default options.

Figure 2.  TextPad install page

Installation Note:

Reboot your PC for all the configuration settings to apply to your PC.

Writing your First Java Program

Open up your TextPad editor and type the following piece of code into your edit window and save the file as Cool.java.  (Note:  Make sure that you save the file with the file-type as .java)

public class Cool {
	public static void main(String[] args) {
		System.out.println("Java is Cool!");
	}
}

Writing your First Java Servlet

Open up your TextPad editor and type the following piece of code into your edit window and save the file as HelloServlet.javain the following folder C:\jsdk2.1\webpages\Web-inf\servlets

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloServlet extends HttpServlet { 
    public void doGet(HttpServletRequest req, HttpServletResponse res)
		throws ServletException, IOException       {
			String name = req.getParameter("name"); 
		res.setContentType("text/html");

       ServletOutputStream out = res.getOutputStream();
		out.println("<b>"); 

       if (name == null) {
			name = "Bill";
		} 

       if (name.equals("John")) { // put your name here
           out.println("<font color=\"red\">" + "Hello " + name + "</font>");
		} else {
			out.println("Hello " + name);
		}

		out.println("</b>");
    }
} 

Compile it within TextPad.

Running your First Java Servlet

Run (double-click) on the following batch file:  C:\jsdk2.1\startserver.bat 

Start Internet Explorer or Netscape and issue the following URL: 

http://localhost:8080/servlet/HelloServlet 

View the source generated from the above request. 

Issue the following URL request: 

http://localhost:8080/servlet/HelloServlet?name=John 

View the source generated from the above request.