Dot Drawing Program (Java GUI + File I/O + Exceptions)

This Java project is a dot-drawing application I developed for my CS 46B course (Data Structures & Algorithms in Java). It uses object-oriented design, Java I/O, exception handling, and a simple GUI to visualize dots read from a structured text file.

Project Description

The program allows users to load a .txt file containing dot descriptions, each defined by a color, x/y position, and radius. Once loaded, the application parses the data, validates it, and draws each dot onto a graphical canvas. I implemented input parsing, error checking, exception handling, and object visualization from scratch.

The application structure follows a modular design with a focus on data validation and extensibility.

Features

• File I/O: Reads comma-separated values from a text file using BufferedReader.
• Exception Handling:
  • Throws an IllegalArgumentException for unsupported colors.
  • Includes a custom DotException class to handle malformed file input.
• Custom Classes:
  • Dot.java: Represents individual dots with color, coordinates, and radius.
  • DotReader.java: Parses dot data from a file and constructs objects.
  • DotException.java: Handles non-standard formatting errors.
  • DotDisplay.java: Uses Java AWT/Swing to render dots visually in a window.
• Graphical Interface:
  • Simple Java Swing GUI with a “Read” button to load and render dot data.
• Data Validation:
  • Validates color against a fixed list of legal values.
  • Validates input formatting and field types.
• Debugging Support:
  • Includes a main() method and breakpoint-friendly design for testing and inspection.

Sample Output

Graphical Output Example:

Theme Inspiration:

File Format

Each line in the input file must include:

COLOR,X,Y,RADIUS

Example:

RED,100,200,20

Running the Program

1. Clone the repository or download the files.
2. Open the project in Eclipse or any Java IDE.
3. Ensure all source files are in a dotlab package.
4. Compile and run DotDisplay.java.
5. Click "Read..." to open the input file (e.g. 3dots.txt) and view the visual output.

Technologies Used

• Java
• AWT/Swing
• Exception Handling
• File I/O
• Eclipse IDE

Reflections

This project helped me strengthen my understanding of file parsing, object-oriented principles, custom exception design, and basic GUI programming. Debugging and validation played a crucial role in ensuring robustness and user-friendly feedback when dealing with bad input.

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Author: Richa Vakharia
Course: CS 46B – Data Structures & Algorithms in Java