Design
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Design

Simulator exercises the Roulette simulation with a given Player placing bets. It reports raw statistics on a number of sessions of play.

Handling Lists of Values in Java

Python programmers can skip this tip because Python can use lists of simple integer values. Using the map and reduce functions, Python programmers can implement handy statistical functions.

Java programmers can't easily accumulate a List of int values. This is because a primitive int value is not an object. The usual solution is to make an Integer value from the int, and put the Integer object into the list.

When getting values back out of the list, there is a two-step dance: cast the item in the list to be an Integer, then get the int value of that object. The following examples show this as two steps.

Example 13.1. Java Explicit Iteration Through a List of Integers

Integer tempMax = (Integer)iterator.next()) 1
int aMax = tempMax.intValue(); 2
1

This gets the next Object from the iterator, and casts this to be an Integer.

2

This gets the primitive int value from the Integer object.

Some people prefer the following. It is short, a little confusing to first-time programmers, but a common idiom.

Example 13.2. Java Compressed Iteration Through a List of Integers

int aMax = ((Integer)iterator.next()).intValue();

Fields

  • int initDuration = 250;

    The duration value to use when initializing a Player for a session.

  • int initStake = 100;

    The stake value to use when initializing a Player for a session.

  • int samples ;

    The number of game cycles to simulate. A default value of 50 makes sense.

  • List durations ;

    A list of lengths of time the Player remained in the game. Each session of play producrs a duration metric, which are collected into this list.

  • List maxima ;

    A list of maximum stakes for each Player. Each session of play producrs a maximum stake metric, which are collected into this list.

  • Player thePlayer ;

    The betting strategy we are simulating.

  • Game theGame ;

    The casino game we are simulating.

Constructors

  • Simulator(Game game,
              Player player);

    Saves the Player and Game instances so we can gather statistics on the performance of the player's betting strategy.

Methods

  • List session();

    Executes a single game session. The Player is initialized with their initial stake and initial cycles to go. An empty List of stake values is created. The session loop executes until the Player playing returns false. This loop executes the Game cycle; then it gets the stake from the Player and appends this amount to the List of stake values. The List of individual stake values is returned as the result of the session of play.

  • gather();

    Executes the number of games sessions in samples. Each game session returns a List of stake values. When the session is over (either the play reached their time limit or their stake was spent), then the length of the session List and the maximum value in the session List are the resulting duration and maximum metrics. These two metrics are appended to the durations list and the maxima list.

    A client class will either display the durations and maxima raw metrics or produce statistical summaries.

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