Java - Format number to print decimal portion only

问题

Is there a simple way in Java to format a decimal, float, double, etc to ONLY print the decimal portion of the number? I do not need the integer portion, even/especially if it is zero! I am currently using the String.indexOf(".") method combined with the String.substring() method to pick off the portion of the number on the right side of the decimal. Is there a cleaner way to do this? Couldn't find anything in the DecimalFormat class or the printf method. Both always return a zero before the decimal place.

回答1:

You can remove the integer part of the value by casting the double to a long. You can then subtract this from the original value to be left with only the fractional value:

double val = 3.5;
long intPartVal= (long) val;
double fracPartVal = val - intPartVal;
System.out.println(fracPartVal);

And if you want to get rid of the leading zero you can do this:

System.out.println(("" + fracPartVal).substring(1));

回答2:

Divide by 1 and get remainder to get decimal portion (using "%"). Use DecimalFormat to format result (using "#" symbol to suppress leading 0s):

double d1 = 67.22;
double d2 = d1%1;
DecimalFormat df = new DecimalFormat("#.00");
System.out.println(df.format(d2));

this prints .22

回答3:

This will print 0.3

double x = 23.8;
int y =(int)x;
float z= (float) (x % y);
System.out.println(z);

来源：https://stackoverflow.com/questions/5584189/java-format-number-to-print-decimal-portion-only