Randomizer.java

import java.util.Random;

/** Provide control over the randomization of the simulation. By using the shared, fixed-seed
 * randomizer, repeated runs will perform exactly the same (which helps with testing). Set
 * 'useShared' to false to get different random behaviour every time */
public class Randomizer
{
    // The default seed for control of randomization.
    private static final int SEED = 1111;
    // A shared Random object, if required.
    private static final Random rand = new Random(SEED);
    // Determine whether a shared random generator is to be provided.
    private static final boolean useShared = false;

    /** Constructor for objects of class Randomize */
    public Randomizer() {}

    /** Provide a random generator.
     * @return A random object */
    public static Random getRandom() {
        if(useShared) {
            return rand;
        }
        else {
            return new Random();
        }
    }

    /** Reset the randomization.
     * This will have no effect if randomization is not through a shared Random generator */
    public static void reset() {
        if(useShared) {
            rand.setSeed(SEED);
        }
    }
}