Java Utililty Methods Random String

String newstring = new String();
int i;
final char[] chars = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q',
        'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',
        'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '!', '@', '#', '$', '%',
        '^', '&', '*', '(', ')', '_', '-', '=', '+', '{', '}', '[', ']', '|', ':', ';', ',', '.', '?', '/',
        '~' }; 
int strlen = (int) Math.floor(rand.nextDouble() * ((max - min) + 1));
...

final Set<String> res = new HashSet<>();
while (res.size() != size) {
    final String color = colors.get(RANDOM.nextInt(colors.size()));
    res.add(color);
return new ArrayList<>(res);

ArrayList<String> list = new ArrayList<String>();
StringTokenizer st = new StringTokenizer(equation);
while (st.hasMoreTokens()) {
    String element = st.nextToken();
    if (!element.equals("+") && !element.equals("->")) {
        list.add(element);
return list.get((int) (Math.random() * list.size()));

Random r = new Random();
int Low = 1;
int High = 10;
int R;
switch (tier) {
case 1:
    Low = 1;
    if (lvlRange.equalsIgnoreCase("high"))
...

Random generator = new Random();
char str[] = new char[length];
for (int i = 0; i < length; i++) {
    str[i] = CHARACTERS[51 + generator.nextInt(10)];
return new String(str);

return intPadString(rnd.nextInt(maxValue), strLen);

StringBuilder sb = new StringBuilder();
for (int i = 0; i < strLen; i++) {
    sb.append(digitsBase36.charAt(rnd.nextInt(36)));
return sb.toString();

String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
Random random = new Random();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 16; i++) {
    int number = random.nextInt(base.length());
    sb.append(base.charAt(number));
return sb.toString();
...

StringBuilder sb = new StringBuilder();
for (int i = 0; i < 16; i++) {
    sb.append(RANDOM_STR.charAt(RANDOM.nextInt(RANDOM_STR.length())));
return sb.toString();

String DATE_FORMAT = "yyyy-MM-dd-HH-mm-ss";
DateFormat df = new SimpleDateFormat(DATE_FORMAT);
String rand = df.format(new Date(System.currentTimeMillis()));
return rand;