Java Utililty Methods Random String

Random r = new Random();
TreeMap<String, Integer> new_map = new TreeMap<String, Integer>();
for (String m : map.keySet()) {
    new_map.put(r.nextInt(10) + ":" + m, map.get(m));
return new_map;

StringBuilder builder = new StringBuilder();
int pos = 0;
while (pos < str.length()) {
    int codePoint = str.codePointAt(pos);
    pos += Character.charCount(codePoint);
    switch (nextInt(random, 0, 2)) {
    case 0:
        builder.appendCodePoint(Character.toUpperCase(codePoint));
...

in = Math.max(1, Math.min(in, 256));
StringBuffer sb = new StringBuffer();
for (int i = 0; i < in; i++) {
    char c = (char) Math.min('9', ('0' + randomInt(10)));
    sb.append(c);
return (sb.toString());

return randomRealisticUnicodeString(r, 20);

return "test_" + Long.toHexString(Double.doubleToLongBits(Math.random()));

return Long.toString(random.nextLong(), 36);

Random random = new Random();
final char[] chars = new char[length];
for (int i = 0, x = chars.length; i < x;) {
    do {
        final int cp = random.nextInt(0x10FFFF + 1);
        if (!Character.isDefined(cp)) {
            continue;
        final char[] chs = Character.toChars(cp);
        if (chs.length > x - i) {
            continue;
        for (final char ch : chs) {
            chars[i++] = ch;
        break;
    } while (true);
return new String(chars);

StringBuilder sb = new StringBuilder();
for (int i = 0; i < len; i++) {
    sb.append(randomLetter());
return sb.toString();

if (length < 1) {
    return null;
if (randGen == null) {
    synchronized (initLock) {
        if (randGen == null) {
            randGen = new Random();
            numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyz"
...

char[] chars = "ab1@cd2#ef3$gh4%ij5^kl6&mn7_op8-qr9?st0~uv3~wx7!yz".toCharArray();
StringBuilder sb = new StringBuilder();
Random random = new Random();
for (int i = 0; i < length; i++) {
    char c = chars[random.nextInt(chars.length)];
    sb.append(c);
return sb.toString();
...