I would like to have a numeric variable that contains integer number with nanosecond precision. I tried this:
Instant t = Instant.now();
a = BigDecimal.valueof(t.getEpochSecond() * 1e9 + t.getNano());
b = BigDecimal.valueof(t.getEpochSecond() * 1e9 + t.getNano() + 1);
Both a and b are contains same value (e.g. 1.60681511777265408E+18), the +1 operation is lost here.
Any idea how to deal with this precision? The goal of it is to keep nanosecond-precision timestamp for time column in InfluxDB. I understand it has something to do with double precision (Java BigDecimal difference), but I haven't found any working solution yet.
Just do the operations with the methods in BigDecimal. And make sure you don't use valueOf(double). You can use valueOf(long), however.
BigDecimal a = BigDecimal.valueOf(t.getEpochSecond())
.multiply(BigDecimal.valueOf(1_000_000_000))
.add(BigDecimal.valueOf(t.getNano()));
BigDecimal b = BigDecimal.valueOf(t.getEpochSecond())
.multiply(BigDecimal.valueOf(1_000_000_000))
.add(BigDecimal.valueOf(t.getNano()))
.add(BigDecimal.ONE);
Printing a and b gives something like:
1606815981554921000
1606815981554921001
If you're storing an integer value, why use a BigDecimal instead of a BigInteger?
import java.time.*;
import java.math.*;
public class MyClass {
public static void main(String args[]) {
Instant t = Instant.now();
BigInteger a = BigInteger.valueOf(t.getEpochSecond() * 1_000_000_000
+ t.getNano());
BigInteger b = BigInteger.valueOf(t.getEpochSecond() * 1_000_000_000
+ t.getNano() + 1);
System.out.println(a); // 1606816120696314000
System.out.println(b); // 1606816120696314001
}
}
Need to switch to BigInteger math methods in the year 2262 though, because the long argument will start overflowing.