Resources to make teaching Java faster, more effective and more fun.
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The hsa package

Introduction

The classes make it easier for users to begin writing programs that explore the basic concepts of computer science before coming to terms with the input and output methods of the Java class library.

To ensure the easiest possible transition from using the hsa package to using only the Java class library, wherever possible we have made the graphics methods in the Console class identical to those in the Java Graphics class. The print and println methods of the Console, Stdout, and TextOutputFile are also the same as those in the Java PrintWriter class. In a number of cases the classes in the hsa package contain extra methods.

To use the hsa classes, the following line must appear in the class header:

        import hsa.*;
  

Applications

Submit

A Java application program used to submit student's assignments for marking.

This brings up dialog boxes to allow the user to enter the name of the program to be submitted, the names of the Java text files that make up the program, and the names of the test data files. It then prints the Java text files, the input files, and the output produced from running the program.

PrintFiles

A Java application program used to print Java files. It can paragraph (indent) the file, bold keywords, and italicize identifiers in the printout if requested.

PrettyPrint

A Java application program to indent (paragraph) Java programs. This can help catch missing curly braces as well as improve program legibility.

This application can also be used to indent programs for systems where tabs stops mean a different number of spaces (in VisualAge for Java tabs are four spaces, in Notepad, tabs are eight spaces) or to change the size of a standard indent.

Classes

Console

The Console window can hold 25 lines of 80 column text. The user can input data directly in the Console window and the output of the program appears there too. Formatted text output is provided. It supports all the basic Java Graphics class methods plus two more to draw stars and maple leaves (suitable for flags).

The Console class window has three buttons. The "Save" button saves the contents of the screen as a ".bmp" (Windows Bitmap) file. The "Print" button prints out the contents of the window. The "Quit" button quits the program immediately. It gives visual notification when the program is finished execution by changing the label in the Quit button to "Close".

TextConsole

The TextConsole window is a 25x80 window used for text output. As the output scrolls off the top of the window, a scroll bar is activated that allows users to view all output from the program. The TextConsole class differs from the Console class in that all text output is kept and can be saved or printed.

The user can input data directly into the Console window. The output of the program also appears there. Formatted text output is provided.

The TextConsole class window has three buttons. The "Save" button saves all output sent to the window to a text file. The "Print" button prints out all of the output. The "Quit" button quits the program immediately. It gives visual notification when the program is finished execution by changing the label in the Quit button to "Close".

Stdin

This is a non-instantiated class to allow users to read all the Java primitive data types from standard input before they have learned about exception handling and the intricacies of the Java primitive wrapper classes. It also makes it possible to read several primitives from one line of input without having to know the StringTokenizer class.

Stdout

This is a non-instantiated class to allow users to output formatted data to standard output without having to learn the java.text.NumberFormat class. Users can write data to fixed length fields and with a fixed number of decimal places.

TextInputFile

This class makes it easier to read from text files. It allows the user to read any Java primitive data type from a text file and does all the conversions, string tokenizing, and exception handling automatically.

TextOutputFile

This class makes it easier to write to text files. It's major convenience is that it handles formatted output. Users can specify field length when outputting primitive data type as well as the number of decimal places when outputting real numbers.

FatalError

This is a class to display fatal errors. When instantiated, it displays a window with a specified message and a button labeled "Quit". When the button is pressed, the program immediately exits. Helpful for users who want to add error checking to their program but are not yet familiar with Frames and the rest of the Java class library.

Message

This is a class to display messages. When instantiated, it displays a window with a specified message and a button labeled "OK". When the button is pressed, the program continues execution.

Status

A quick way of displaying changing status messages without having to learn about Frames, and so on.