How can I truncate a double to only two decimal pl

Question

This question already has answers here:

How to round a number to n decimal places in Java (31 answers)

Closed 3 years ago.

For example I have the variable 3.545555555, which I would want to truncate to just 3.54.

Answer 1

If you want that for display purposes, use java.text.DecimalFormat:

 new DecimalFormat("#.##").format(dblVar);

If you need it for calculations, use java.lang.Math:

 Math.floor(value * 100) / 100;

Answer 2

Note first that a double is a binary fraction and does not really have decimal places.

If you need decimal places, use a BigDecimal, which has a setScale() method for truncation, or use DecimalFormat to get a String.

Answer 3

If, for whatever reason, you don't want to use a BigDecimal you can cast your double to an int to truncate it.

If you want to truncate to the Ones place:

• simply cast to int

To the Tenths place:

• multiply by ten
• cast to int
• cast back to double
• and divide by ten.

Hundreths place

• multiply and divide by 100 etc.

Example:

static double truncateTo( double unroundedNumber, int decimalPlaces ){
    int truncatedNumberInt = (int)( unroundedNumber * Math.pow( 10, decimalPlaces ) );
    double truncatedNumber = (double)( truncatedNumberInt / Math.pow( 10, decimalPlaces ) );
    return truncatedNumber;
}

In this example, decimalPlaces would be the number of places PAST the ones place you wish to go, so 1 would round to the tenths place, 2 to the hundredths, and so on (0 rounds to the ones place, and negative one to the tens, etc.)

Answer 4

Bit Old Forum, None of the above answer worked for both positive and negative values ( I mean for the calculation and just to do truncate without Rounding). From the How to round a number to n decimal places in Java link

private static BigDecimal truncateDecimal(double x,int numberofDecimals)
{
    if ( x > 0) {
        return new BigDecimal(String.valueOf(x)).setScale(numberofDecimals, BigDecimal.ROUND_FLOOR);
    } else {
        return new BigDecimal(String.valueOf(x)).setScale(numberofDecimals, BigDecimal.ROUND_CEILING);
    }
}

This method worked fine for me .

System.out.println(truncateDecimal(0, 2));
    System.out.println(truncateDecimal(9.62, 2));
    System.out.println(truncateDecimal(9.621, 2));
    System.out.println(truncateDecimal(9.629, 2));
    System.out.println(truncateDecimal(9.625, 2));
    System.out.println(truncateDecimal(9.999, 2));
    System.out.println(truncateDecimal(-9.999, 2));
    System.out.println(truncateDecimal(-9.0, 2));

Results :

0.00
9.62
9.62
9.62
9.62
9.99
-9.99
-9.00

Answer 5

Maybe Math.floor(value * 100) / 100? Beware that the values like 3.54 may be not exactly represented with a double.

Answer 6

//if double_v is 3.545555555
String string_v= String.valueOf(double_v);
int pointer_pos = average.indexOf('.');//we find the position of '.'
string_v.substring(0, pointer_pos+2));// in this way we get the double with only 2 decimal in string form
double_v = Double.valueOf(string_v);//well this is the final result

well this might be a little awkward, but i think it can solve your problem :)