Java FAQs and tutorials

Java FAQ's

Path and ClassPath:

PATH

In Windows 9x you would set it up in the autoexec.bat file
ie.
SET PATH=%PATH%;c:\jdk1.4.2\bin\;

where c:\jdk1.4.2\ is the path where you installed Java.

In Windows 2000 and XP
Right click on My Computer->Properties->Advanced Tab->Environment Variables... Button.

If you see a PATH in System Variables, click that and edit it. If you don't, you will need to create a new System variable.

It should look something like this:
%SystemRoot%\system32;%SystemRoot%;c:\jdk1.4.2\bin\;

NOTE: There may be other paths in the PATH variable, leave them there!

CLASSPATH

Eventually you will need to add pre-packaged software to your project.
The way to do this is to set up an environment variable called classpath.

In Windows 9x you would set it up in the autoexec.bat file
ie.
SET CLASSPATH=%CLASSPATH%;c:\MyPackage1.jar;c:\MyPackage2.jar

In Windows 2000 and XP
Right click on My Computer->Properties->Advanced Tab->Environment Variables... Button.

If you see a CLASSPATH in System Variables, click that and edit it. If you don't, you will need to create a new System variable.

In Linux, from my understanding, there are a few ways to do this, but I set up mine in the /etc/profile file:

# Taken directly from /etc/profile in RedHat Linux 8.0
JAVA_HOME="/usr/java/jdk1.3.1_06"
J2EE_HOME="/usr/local/etc/java/j2sdkee1.3.1"
PATH="/usr/java/jwsdp1_0_0_1/bin":$JAVA_HOME:$J2EE_HOME/bin:$J2EE_HOME:$J2EE_HOME/bin:$PATH
JAR_PATH="/usr/local/Jars"
CLASSPATH=$JAR_PATH/jcert.jar:$JAR_PATH/jnet.jar:$JAR_PATH/jsse.jar:$CLASSPATH
export PATH JAVA_HOME J2EE_HOME
export CLASSPATH

What is an IDE?

An IDE(Integrated Development Environment) is a development tool used to make programming easier.

What is a good IDE?

Borland JBuilder
Eclipse
Intellij
JCreator
Macromedia JRun
Sun One Studio

JARS the basics

Basically all a JAR is, is a ZIP file that contains the necessary classes to execute your program.
A Jar is a way to package your classes in one convenient file.

To learn more, follow this link


Eliminate Prompt and Executable Jars

Javaw.exe is intended to run Java programs, just like java.exe, but without the Consol Window.
Suppose you wanted to run a Java program in a Windows Environment, you could create a shortcut to
your program, and the command to run your program would be "javaw myProject.MyProgram"

An Executable JAR is a jar file that has the class with the main method specified in the Manifest.mf file
located in the directory meta-inf/ directory of your JAR.

In a Windows environment, Windows looks in the registry for the associated program to open the JAR file.
In this case javaw.exe. Java looks in the Manifest file for the main method and executes that class.
On other platforms the command to execute a jar would be "javaw -jar myprogram.jar"

A simple example of a manifest would be:

Manifest-Version: 1.0
Main-Class: myProject.MyClassWithMain

My Applet doesn't work and the Java Plugin.

Most browsers have the plugin for Java 1.1, but with the introduction of Swing in Java 1.2, your program
might need a newer plugin for the browser. SUN has come up with a handy little converter that will
change your HTML code to detect and download the newer plugin. It can be found here

Links in an Applet

In a click event for some Component, you could use the following code:

Code:

//To send the current page to a new location, the code would be:
this.getAppletContext().showDocument(new URL("http://www.google.com"));

//To open a new Browser Window: 
this.getAppletContext().showDocument(new URL("http://www.google.com"),"_blank");

I apologize that it took so long for me to get this up. It isn't finished yet, and if you have any suggestions, you may contact me here.

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