Format Float to n decimal places
JavaAndroidFloating PointNumbersFormatJava Problem Overview
I need to format a float to "n"decimal places.
was trying to BigDecimal, but the return value is not correct...
public static float Redondear(float pNumero, int pCantidadDecimales) {
// the function is call with the values Redondear(625.3f, 2)
BigDecimal value = new BigDecimal(pNumero);
value = value.setScale(pCantidadDecimales, RoundingMode.HALF_EVEN); // here the value is correct (625.30)
return value.floatValue(); // but here the values is 625.3
}
I need to return a float value with the number of decimal places that I specify.
I need Float
value return not Double
.
Java Solutions
Solution 1 - Java
Solution 2 - Java
Take a look at DecimalFormat. You can easily use it to take a number and give it a set number of decimal places.
Edit: Example
Solution 3 - Java
Try this this helped me a lot
BigDecimal roundfinalPrice = new BigDecimal(5652.25622f).setScale(2,BigDecimal.ROUND_HALF_UP);
Result will be roundfinalPrice --> 5652.26
Solution 4 - Java
Of note, use of DecimalFormat
constructor is discouraged. The javadoc for this class states:
> In general, do not call the DecimalFormat constructors directly, since the NumberFormat factory methods may return subclasses other than DecimalFormat.
https://docs.oracle.com/javase/8/docs/api/java/text/DecimalFormat.html
So what you need to do is (for instance):
NumberFormat formatter = NumberFormat.getInstance(Locale.US);
formatter.setMaximumFractionDigits(2);
formatter.setMinimumFractionDigits(2);
formatter.setRoundingMode(RoundingMode.HALF_UP);
Float formatedFloat = new Float(formatter.format(floatValue));
Solution 5 - Java
Here's a quick sample using the DecimalFormat
class mentioned by Nick.
float f = 12.345f;
DecimalFormat df = new DecimalFormat("#.00");
System.out.println(df.format(f));
The output of the print statement will be 12.35. Notice that it will round it for you.
Solution 6 - Java
Kinda surprised nobody's pointed out the direct way to do it, which is easy enough.
double roundToDecimalPlaces(double value, int decimalPlaces)
{
double shift = Math.pow(10,decimalPlaces);
return Math.round(value*shift)/shift;
}
Pretty sure this does not do half-even rounding though.
For what it's worth, half-even rounding is going to be chaotic and unpredictable any time you mix binary-based floating-point values with base-10 arithmetic. I'm pretty sure it cannot be done. The basic problem is that a value like 1.105 cannot be represented exactly in floating point. The floating point value is going to be something like 1.105000000000001, or 1.104999999999999. So any attempt to perform half-even rounding is going trip up on representational encoding errors.
IEEE floating point implementations will do half-rounding, but they do binary half-rounding, not decimal half-rounding. So you're probably ok
Solution 7 - Java
public static double roundToDouble(float d, int decimalPlace) {
BigDecimal bd = new BigDecimal(Float.toString(d));
bd = bd.setScale(decimalPlace, BigDecimal.ROUND_HALF_UP);
return bd.doubleValue();
}
Solution 8 - Java
This is a much less professional and much more expensive way but it should be easier to understand and more helpful for beginners.
public static float roundFloat(float F, int roundTo){
String num = "#########.";
for (int count = 0; count < roundTo; count++){
num += "0";
}
DecimalFormat df = new DecimalFormat(num);
df.setRoundingMode(RoundingMode.HALF_UP);
String S = df.format(F);
F = Float.parseFloat(S);
return F;
}
Solution 9 - Java
I was looking for an answer to this question and later I developed a method! :) A fair warning, it's rounding up the value.
private float limitDigits(float number) {
return Float.valueOf(String.format(Locale.getDefault(), "%.2f", number));
}
Solution 10 - Java
I think what you want ist
return value.toString();
and use the return value to display.
value.floatValue();
will always return 625.3 because its mainly used to calculate something.
Solution 11 - Java
You can use Decimal format if you want to format number into a string, for example:
String a = "123455";
System.out.println(new
DecimalFormat(".0").format(Float.valueOf(a)));
The output of this code will be:
123455.0
You can add more zeros to the decimal format, depends on the output that you want.