Java Plinko

This is a Plinko game from the game show The Price Is Right written in Java with Maven and JUnit. A chip is dropped from the middle slot of a 9x13 board, bounces on pegs on its way down, and then lands in one of nine buckets.

This experiment is run 10,000 times, and then the actual results are compared to the expected results based on the probability of the chip landing in each bucket. The actual results compared to the expected results are extremely close, often within less than 1% difference for each bucket.

How This Project Was Created

1. Install Java

2. Set Java environment variable in ~/.bash_profile file:

export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk-18.jdk/Contents/Home"

3. Verify Java is installed by running java -version. Output looks like:

java version "18" 2022-03-22
Java(TM) SE Runtime Environment (build 18+36-2087)
Java HotSpot(TM) 64-Bit Server VM (build 18+36-2087, mixed mode, sharing)

4. Download Maven

5. Set Maven environment variables in ~/.bash_profile file:

export MAVEN_ROOT="$HOME/Code/apache-maven-3.8.5"
export PATH="$MAVEN_ROOT/bin:$PATH"

6. Verify Maven is installed by running mvn --version. Output looks like:

Apache Maven 3.8.5 (3599d3414f046de2324203b78ddcf9b5e4388aa0)
Maven home: /Users/tylerhawkins/Code/apache-maven-3.8.5
Java version: 18, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk-18.jdk/Contents/Home
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.14.4", arch: "x86_64", family: "mac"

7. Generate the plinko project using the maven-archetype-quickstart plugin:

mvn archetype:generate -DgroupId=com.tylerhawkins.examples -DartifactId=plinko -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

The newly created project directory structure will look like this:

8. Add the following properties to the pom.xml file to specify the version of Java you'd like to use:

<properties>
  <maven.compiler.source>18</maven.compiler.source>
  <maven.compiler.target>18</maven.compiler.target>
</properties>

9. Rename App.java and AppTest.java files to be PlinkoGame.java and PlinkoGameTest.java

10. In the pom.xml file, upgrade JUnit from 3.8.1 to 4.13.2 by replacing the version number

11. Write some code to build the Plinko game!

Build and Test the App

To build and test the app, run the following from the project root directory:

mvn clean package

Run the App

To run the Plinko app, run the following from the project root directory:

java -cp target/classes com.tylerhawkins.examples.PlinkoGame

Alternatively, you can run the JAR file by doing:

java -cp target/plinko-1.0-SNAPSHOT.jar com.tylerhawkins.examples.PlinkoGame

Either approach will run the app.

The experiment results will then be output to your console and look something like this:

----------------------------
| Slot | Expected | Actual |
|--------------------------|
| 1    | 0.019    | 0.015  |
| 2    | 0.054    | 0.054  |
| 3    | 0.121    | 0.126  |
| 4    | 0.193    | 0.202  |
| 5    | 0.226    | 0.220  |
| 6    | 0.193    | 0.191  |
| 7    | 0.121    | 0.123  |
| 8    | 0.054    | 0.053  |
| 9    | 0.019    | 0.017  |
----------------------------

Resources

• Maven Quick Guide
• Apache Maven Project
• Maven in 5 Minutes
• W3 Schools Java Tutorial
• Install Java SE 18 for Mac
• JUnit
• Plinko