Java, JPython, and Netscape

Contents

• Java
  • Java Documentation
  • Java Books
  • The Java Plug-in
• JPython
  • JPython Documentation
  • Using JPython

Java

Version 1.3 of the Java Development Kit (JDK) is installed on the computers running linux. To use Java you need the directory

/APPS/jdk1.3/bin

You can tell if this directory is in your path by saying

which java

/APPS/jdk1.3/bin/java

PATH=/APPS/jdk1.3/bin:$PATH

Java Documentation

Documentation that comes with this implementation is found at the URL

file:/APPS/jdk1.3/docs/index.html

All of this documentation and lots more can be found at http://java.sun.com.

Java Books

Recommended (by me) reading for Java programmers are the following

• The Java Programming Language, Third Edition, by Arnold and Gosling published by Addison-Wesley. in book form.

  This is like K & R for C, the one book every Java programmer must have, the right introduction to Java.

• The Java Tutorial available on-line at http://java.sun.com and also published by Addison-Wesley. in book form.

  A very helpful and easy going introduction to many topics in java with lots of good examples.

• Java Design by Coad and Mayfield published by Prentice-Hall.

  An introduction to Object-Oriented Programming (OOP) and Object-Oriented Design (OOD) using Java for examples. Because it uses Java it stresses some topics not covered adequately in most OOP/OOD books, in particular interfaces and threads. If you want to know what the point of interfaces is, read this book.

The Java Plug-in

To make and use Java applets using new features of Java, you need to use the java plug-in for netscape.

These installation instructions are copied from http://java.sun.com/j2se/1.3/install-linux-sdk.html.

1. Uninstall previous installation of the Java Plug-in, if applicable.

   rm -fr $HOME/.netscape/java
   rm $HOME/.netscape/plugins/javaplugin.so
   

   (You shouldn't need to do this. SuSE 6.4, at least didn't come with the plug-in installed).
2. Set the NPX_PLUGIN_PATH environment variable before you run netscape.

   export NPX_PLUGIN_PATH=/APPS/jdk1.3/jre/plugin/i386
   netscape
   

   (in order for this environment variable to effect netscape, you must run netscape from the command line, not by clicking on some icon somewhere on your desktop).
3. You may need to close and restart netscape a couple of times before the plug-in will work because of bug 4358142.
4. You can test whether the plug-in is working by visiting the page

   http://java.sun.com/docs/books/tutorial/uiswing/start/swingApplet.html

   and clicking on the HelloSwingApplet.html link.

   You should see a box that looks like

   

JPython

JPython 1.1 is installed on the computers running linux. To use JPython you need the directory

/APPS/JPython11

You can tell if this directory is in your path by saying

which jpython

/APPS/JPython11/jpython

PATH=/APPS/JPython11:$PATH

JPython Documentation

The top-level page of the documentation that comes with this installation is

file:/APPS/JPython11/docs/index.html

Using JPython

Python is an object-oriented scripting language. JPython is a complete Python implementation in 100% pure Java in which it is easy to use Java objects. In case it isn't obvious what the example on that page does. It creates a JPython object that is really just a Java object, an instance of the class java.util.Random. Then it calls some of the object's methods. In case that still isn't obvious, this object is written in Java and no different from any object written in Java, for example, one you might write yourself. It just works!