Learning Objects for Java (Overview)

Overview:

Learning objects (LOs) are small, self-contained, reusable resources for learning. The advantages of LOs include: flexibility of use (students can choose to work with LOs at their convenience) and adaptability (students can choose to work only with those LOs that address topics they find difficult).

This collection contains five modules, each with about ten LOs for the topic of the module: control structures, arrays, methods, constructors, inheritance.

The LOs in this collection are designed for use with the Jeliot system for animating introductory programs in Java.

A learning object consists of text and Java programs. Each LO is independent, so if you know the needed background material you can go directly to any LO. For each topic, a table is given that lists the LOs, the associated source files, and the “prerequisites” for each LO. The prerequisites are the number of the LO that introduces concepts that are assumed; however, there is no need to actually work through the LOs in sequence.

The text for each LO starts with a description of the concept being presented and an overview of the example program. It is followed by a bulleted list for each program that describes what to observe as you step through the program with Jeliot. The text for the LO ends with a programming exercise.

Installation:

Before you begin, download and install Jeliot from the link given in the sidebar. Download the zip files with the source code for each of the LOs. There is a zip file associated with each module that contains the source files for the LOs for its topic; in addition, there is a zip file learning-objects.zip with the source files for all the LOs in the collection.

Tips for using Jeliot:

• The LOs have been tested with Jeliot Version 3.7.1; please ensure that you are not using earlier versions.
• Copy the source file directories to a clean directory so that if you make changes you will not modify the original files. Run Jeliot and open the source file for the LO you want to work with.
• Learn how to use Jeliot before studying the LOs. In particular, learn how to use Step, Pause, Play, and Rewind to control the animation.
• Select Animation / Run Until... (ctrl-T) and enter a line number to begin the animation at that line. This is very useful in two situations:
  • when you are animating a program several times and wish to skip over the initialization or other parts of the code;
  • when you wish to examine the final state after the last line of the main method: enter the line number of the closing brace of the main method.
• Select Options / Show History View to enable storing of each step of the animation; these can be viewed by selecting the History tab on the right-hand side of the display. Enabling the history may slow Jeliot down, especially for large programs.
• The programs in the LOs use standard Java with two exceptions that simplify the animations:
  • None of the programs use the parameter of the main method. Since Jeliot accepts Java programs without the formal parameter definition String[] args, the parameter has been commented-out in the programs. You can remove the comments to compile the programs with a Java compiler. If you wish to run Jeliot with the parameter, you can selectOptions / Use Null Parameter to Call Main to skip over the animation of the parameter.
  • Two of the LOs on control structures use the input statement: input = Input.nextInt(). To compile these programs with standard Java, add the following declaration to the main method:

     java.util.Scanner Input = new java.util.Scanner(System.in)