public class ColorUtil {

    public static final ColorUtil INSTANCE = new ColorUtil();

    private final HashMap<Integer, String> hashtable = new HashMap<>();

    public ColorUtil() {
        hashtable.put(0, "red");
        hashtable.put(1, "lightred");
        hashtable.put(2, "amaranthPink");
        hashtable.put(3, "brightOrangeYellow");
        hashtable.put(4, "lightorange");
        hashtable.put(5, "paleOrangeYellow");
        hashtable.put(6, "rapeseedYellow");
        hashtable.put(7, "yellow");
        hashtable.put(8, "brightYellow");
        hashtable.put(9, "lemonChiffon");
        hashtable.put(10, "green");
        hashtable.put(11, "irishGreen");
        hashtable.put(12, "paleGreen");
        hashtable.put(13, "brightGreen");
        hashtable.put(14, "blue");
        hashtable.put(15, "cyan");
        hashtable.put(16, "lightBlue");
        hashtable.put(17, "magenta");
        hashtable.put(18, "halfMagenta");
        hashtable.put(19, "paleMagenta");
        hashtable.put(20, "darkGray");
        hashtable.put(21, "gray");
        hashtable.put(22, "lightGray");
    }

    /**
     *
     * @param colorNum key in hashTable
     * @return 0 = red; 1 = lightred; 2 = amaranthPink; 3 = brightOrangeYellow;
     * 4 = lightorange; 5 = paleOrangeYellow; 6 = rapeseedYellow; 7 = yellow; 8
     * = brightYellow; 9 = lemonChiffon; 10 = green; 11 = irishGreen; 12 =
     * paleGreen; 13 = brightGreen; 14 = blue; 15 = cyan; 16 = lightBlue; 17 =
     * magenta; 18 = halfMagenta; 19 = paleMagenta; 20 = darkGray; 21 = gray; 22
     * = lightGray;
     */
    @SuppressWarnings("empty-statement")
    public String getColorName(int colorNum) {
        String colorName = "";
        try {
            colorName = hashtable.get(colorNum);;
        } catch (NullPointerException e) {
            System.out.println("key of color not found in hashMap: " + e);
        }
//        System.out.println(colorNum + " = " + colorName + ";");
        return colorName;
    }

    public static void main(String[] args) {
        ColorUtil colorUtil = ColorUtil.INSTANCE;
//        for (int i = 0; i <= 22; i++) {
//            colorUtil.getColorName(i);
//        }
        colorUtil.getColorName(2);
    }
}

public class ColorCollection {

    public static final ColorCollection INSTANCE = new ColorCollection();

    private final HashMap<Integer, String> hashmap = new HashMap<>();

    private ColorCollection() {
        hashmap.put(0, "red");
        hashmap.put(1, "lightred");
        hashmap.put(2, "amaranthPink");
        hashmap.put(3, "brightOrangeYellow");
        hashmap.put(4, "lightorange");
        hashmap.put(5, "paleOrangeYellow");
        hashmap.put(6, "rapeseedYellow");
        hashmap.put(7, "yellow");
        hashmap.put(8, "brightYellow");
        hashmap.put(9, "lemonChiffon");
        hashmap.put(10, "green");
        hashmap.put(11, "irishGreen");
        hashmap.put(12, "paleGreen");
        hashmap.put(13, "brightGreen");
        hashmap.put(14, "blue");
        hashmap.put(15, "cyan");
        hashmap.put(16, "lightBlue");
        hashmap.put(17, "magenta");
        hashmap.put(18, "halfMagenta");
        hashmap.put(19, "paleMagenta");
        hashmap.put(20, "darkGray");
        hashmap.put(21, "gray");
        hashmap.put(22, "lightGray");
    }

    /**
     *
     * @param colorNum key in hashmap
     * @return 0 = red; 1 = lightred; 2 = amaranthPink; 3 = brightOrangeYellow;
     * 4 = lightorange; 5 = paleOrangeYellow; 6 = rapeseedYellow; 7 = yellow; 8
     * = brightYellow; 9 = lemonChiffon; 10 = green; 11 = irishGreen; 12 =
     * paleGreen; 13 = brightGreen; 14 = blue; 15 = cyan; 16 = lightBlue; 17 =
     * magenta; 18 = halfMagenta; 19 = paleMagenta; 20 = darkGray; 21 = gray; 22
     * = lightGray;
     */
    public String getColorName(int colorNum) {
        return hashmap.get(colorNum);
    }
}