Truly random double example

gistfile1.txt

    import java.util.ArrayList;
    import java.util.List;
    import java.util.Random;
    
    public class Example2 {
    
        /**
         * A final List<Double> of all previous double generated with
         * generateUniqueDouble(), turned into a string with Double.valueOf(d);
         */
        private static final List<Double> PREVIOUS = new ArrayList<Double>();
    
        /**
         * The RANDOM variable used in the class.
         */
        private static final Random RANDOM = new Random();
    
        /**
         * Generates a truly unique double.
         * 
         * @param previous
         *            A List<Double> of previous doubles, converted into a Double
         *            with Double.valueOf(d);
         * @return a UUID generated with UUID.randomUUID(); that is not included in
         *         the given List<Double>.
         */
        public static double generateUniqueDouble(List<Double> previous) {
            double d = RANDOM.nextDouble();
            if (previous.contains(Double.valueOf(d))) {
                return generateUniqueDouble(previous);
            }
            return d;
        }
    
        /**
         * Generates a truly unique double using the final List<Double> PREVIOUS
         * variable defined at the top of the class.
         * 
         * @return A truly random double created with generateUnique(List<Double>
         *         previous);
         */
        public static double generateUnique() {
            double d = RANDOM.nextDouble();
            PREVIOUS.add(Double.valueOf(d));
            return d;
        }
    
    }