问题
I have a number of type BigDecimal, for example 18446744073709551616, and I want to convert it to hexadecimal value. I'm fine with truncating the fractional portion.
Is there a way to do this instead of doing it manually?
回答1:
Judging by your example you should use BigInteger instead of BigDecimal. This way you could use
new BigInteger("18446744073709551616").toString(16)
If you can't change type of original object convert it to BigInteger later in method
new BigDecimal("18446744073709551616").toBigInteger().toString(16);
回答2:
Take into account that converting a decimal value into hex requires an exponent. You could get the hexadecimal String representing a numeric value using Formatter.
%A : The result is formatted as a hexadecimal floating-point number with a significand and an exponent
%X: The result is formatted as a hexadecimal integer
Use the %A conversion if you want to convert a decimal value:
System.out.println(String.format("%A", myBigDecimal));
Curiously, the code above is correct regarding the javadoc for Formatter, but there seems to be a related 9-year-old error in the javadocs, that has been fixed a few weeks ago in Java 8: 5035569 : (fmt) assertion error in Formatter for BigDecimal and %a. You can use the analog code below:
System.out.println(String.format("%A", myBigDecimal.doubleValue()));
EDIT
Judging by the value in your post, you don't really care about the fractional part. You could use the %X conversion in the pattern and just provide the BigInteger representation:
BigDecimal bd = new BigDecimal("18446744073709551616");
System.out.println(String.format("%X", bd.toBigInteger()));
回答3:
Theoretically it is possible to represent BigDecimal as a hex string, simiolar to Double.toHexString
0x1.199999999999p+1
but AFAIK there is no standard way to do it and custom implementation will not be easy
来源：https://stackoverflow.com/questions/15615800/how-to-convert-only-the-integer-part-of-a-bigdecimal-to-hex-string