bshapka / life-in-java

A Java implementation of Conway's Game of Life

Life in Java

This project is an implementation of Conway's Game of Life (or Life for short) in Java.

About Life

For information about the game, see About Life. For information about the creator of the game, see About John Conway.

Running the Project

The following is a set of recommended directions for running the project. Note that these directions assume a JRE exists and that it has been associated with the shell command java. The project was developed and tested with the Java 16.0.1 SDK and language level set to 14. Compatibility with older JREs may exist but is not guaranteed.

• Download the supplied jar file from Releases
• Start a shell session and navigate to the directory containing the downloaded jar file
• Run the command java -jar life-in-java.jar to start the application (assuming the jar file was not renamed)

Note that if you download the source code and attempt to run the project, you will need to add JUnit 5.4 to the classpath.

Implementation Details

This section assumes basic familiarity with Life. If you are not familiar with Life but want to read this section, please read the section About Life, or consult a source like Wikipedia on the game.

All source files are well-documented, so explanations of or details about these files will not be supplied here.

Common implementations of Life represent the state of a world as a 2D list of bits or booleans. Typically a live cell is truthy while a dead cell is falsy. While this approach is intuitive, dead calls don't need to be stored, and doing so can have notable costs in terms of memory usage.

An alternative approach is to store only the coordinates of live cells, requiring significantly less memory. By representing coordinates as tuples and storing them in a set, further efficiencies are gained via hashing.

This implementation uses a toroidal grid. As such, objects that leave the screen on one edge will re-enter the screen with the same trajectory and velocity at the equivalent location on the opposing edge.