Japa Guide

(These notes are basically the same as the help page that comes as part of japa.)

What you see...

Japa Screenshot
  • There are only two buttons - Compile and Run.
  • Clicking on an error message takes you to the appropriate line
  • The horizontal line between the edit area and error area can be re-positioned.

To Create a Java Applet

Choose File| New Applet. Pick a class name, and follow the instructions. A skeleton program will be created, with 2 buttons and text fields.

To Create a Java GUI Application

Choose File| New GUI Application. Pick a class name, and follow the instructions. A skeleton program will be created, with 2 buttons and text fields.

To Create a Java Console (non-GUI) Application

Choose File| New Console Application. Pick a class name, and follow the instructions. A small program containing a 'main' method will be created.

How to find compilation errors

The compilation error messages are difficult for beginners to understand - whatever the language you use. In Japa, click on an error message line to be taken to the line in question. Sometimes though, the error is at a different line.

In Java, the curly brackets { } are tricky. Japa provides some tools:

The main one is Tools|Pretty-Printer (new in v2) which formats your code so that the matching { and } can be spotted. If the appearance is not what you intended, then edit your code.

Choosing Tools| Count { } - displays how many { and } there are in your program. These numbers should be equal.

Also , you can click in a line containing a {, then click on Tools|find matching }.
This displays the line number of the matching }. (Note the line number display at the top of the screen.) If the matching } is not the one you were expecting, work through your program, carefully inspecting your curly brackets.

There is an additional tool which is useful - Lines containing - which can help you to spot compilation errors, or can assist you with documentation. It displays lines containing (or not containing) a specified string. Look at the help file for details.

How to use several classes

Japa creates the class files in the same folder as the java source files. So for a program spread over several files, put all the files in the same folder.

How to use Swing GUI components

You can use Swing as long as the version of Java you use has the Swing libraries. All the SDKs support Swing.

How to run Japa on a network

Most people won't want to do this, but here is some detailed info on ini files, etc.

Is Japa written in Java?

No. Sorry. I wanted a system which would work with early (small) versions of java - not the massive new versions. The AWT is not quite powerful enough for this, so Japa it is written in Delphi (although the Java Swing components would have been fine for the task as well.) The source is available - send me an email if you want it.