Java - Convert hex to IEEE-754 64-bit float - double precision

Question

I'm trying to convert the following hex string: "41630D54FFF68872" to 9988776.0 (float-64).

With a single precision float-32 I would do:

int intBits = Long.valueOf("hexFloat32", 16).intValue();
float floatValue = Float.intBitsToFloat(intBits);

but this throws a: java.lang.NumberFormatException: Infinite or NaN when using the 64-bits hex above.

How do I convert a hex to a double precision float encoded with IEEE-754 with 64 bits?

Thank you

Answer 1

You want double-precision, so Float isn't the right class - that's for single precision.

Instead, you want the Double class, specifically Double.longBitsToDouble.

Answer 2

Almost correct. Just omit the double quotes in the valueOf call:

String hexString = "41630D54FFF68872";
long longBits = Long.valueOf(hexString,16).longValue(); 
double doubleValue = Double.longBitsToDouble(longBits);
System.out.println( "double float hexString is = " + doubleValue );