Converting 64-bit unsigned int (in hex string form) to decimal in java

Question

I have a hex string that represents a 64-bit unsigned int.

I want to convert this to a decimal representation in java.

I wanted to use Long.parseLong("HexString", 16); but in java the leftmost bit is the sign bit and any number greater than 2^31-1 would not fit.

SO how do i convert and store this data?

Thanks, Sunny

rgettman · Accepted Answer · 2014-09-26 21:28:08Z

9

You can create a BigInteger using the constructor that takes a String and an int radix.

BigInteger bigInt = new BigInteger(hexString, 16);

If you have Java 8, you can use Long.parseUnsignedLong, which will allow you to parse all 64 bits, even if the bit that would normally put it over Long.MAX_VALUE is set. It still returns a long, which in Java is still signed, but it will be parsed as if it were an unsigned long.

long stillSigned = Long.parseUnsignedLong(hexString, 16);

If the value that gets parsed is negative, then the true unsigned value is the signed value + 2⁶⁴.

answered Sep 26, 2014 at 21:28

rgettman

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