Java Utililty Methods BigInteger Calculate

BigInteger value = BigInteger.ZERO.add(num);
String result = "";
while (!value.equals(BigInteger.ZERO)) {
    result = BASE62_DIGITS.charAt(value.mod(SIXTY_TWO).intValue()) + result;
    value = value.divide(SIXTY_TWO);
return result;

final BigInteger encodeLength = BigInteger.valueOf(ENCODE.length());
BigInteger running = input;
BigInteger mod;
final StringBuilder result = new StringBuilder(64);
result.append(running.intValue() == 0 ? "0" : "");
while (running.longValue() != 0) {
    mod = running.remainder(encodeLength);
    result.append(ENCODE.substring(mod.intValue(), mod.intValue() + 1));
...

StringBuilder str = new StringBuilder();
BigInteger primaryKey = new BigInteger(String.valueOf(id));
while (primaryKey.compareTo(BigInteger.ZERO) == 1) {
    str.insert(0, ALPHABET.charAt(primaryKey.mod(BASE).intValue()));
    primaryKey = primaryKey.divide(BASE);
return str.toString();

if (int1.compareTo(int2) == 0) {
    return true;
return false;

int flag = 0;
if (a.length != b.length) {
    return false;
for (int i = 0; i < a.length; i++) {
    flag |= a[i].compareTo(b[i]);
return flag == 0;
...

return bi.testBit(index);

int intpart = extractInt(bi, start + decimal, end);
int decpart = extractInt(bi, start, start + decimal);
float decf = decpart;
while (decf >= 1.0) {
    decf = decf / 10;
float ret = intpart + decf;
return ret;
...

bi = bi.shiftRight(start);
int foo = (int) Math.pow(2, end - start) - 1;
BigInteger mask = BigInteger.valueOf(foo);
bi = bi.and(mask);
return bi.intValue();

for (int i = array.length - 1; i >= 0; i--) {
    array[i] = value;

return i;