How to convert 'unsigned long' to string in java

Question

it is clear that java does not have 'unsigned long' type, while we can use long to store a unsigned data. Then how can I convert it to a String or just print it in a 'unsigned' manner?

Answer 1

You need to use BigInteger unfortunately, or write your own routine.

Here is an Unsigned class which helps with these workarounds

private static final BigInteger BI_2_64 = BigInteger.ONE.shiftLeft(64);

public static String asString(long l) {
    return l >= 0 ? String.valueOf(l) : toBigInteger(l).toString();
}

public static BigInteger toBigInteger(long l) {
    final BigInteger bi = BigInteger.valueOf(l);
    return l >= 0 ? bi : bi.add(BI_2_64);
}

Answer 2

As mentioned in a different question on SO, there is a method for that starting with Java 8:

System.out.println(Long.toUnsignedString(Long.MAX_VALUE)); // 9223372036854775807
System.out.println(Long.toUnsignedString(Long.MIN_VALUE)); // 9223372036854775808

Answer 3

Can you use third-party libraries? Guava's UnsignedLongs.toString(long) does this.

Answer 4

long quot = (number >>> 1) / 5L; // get all digits except last one
long rem = number - quot * 10L; // get last digit with overflow trick
String out = Long.toString(quot) + rem;