Rounding Double in Java - Minimum Decimal Places

Question

Possible Duplicate:
Round a double to 2 significant figures after decimal point

The code below works

import java.text.DecimalFormat;

public class Test {
public static void main(String[] args){

    double x = roundTwoDecimals(35.0000);
    System.out.println(x);
}

public static double roundTwoDecimals(double d) {   
    DecimalFormat twoDForm = new DecimalFormat("#.00");
    twoDForm.setMinimumFractionDigits(2);
    return Double.valueOf(twoDForm.format(d));
}
}

it results to 35.0. How to forced the minimum number of decimal places? The output I want is 35.00

The number of trailing zeros is not a property of a `double`, it's a property of a `String` representation. — Oliver Charlesworth, Mar 19 '12 at 20:14
@JRGalia: You have to convert it to `String`, because your question is about human-readable representations of numbers. — Oliver Charlesworth, Mar 19 '12 at 20:18
But if you're asking how to round a `double` value to two decimal digits, the answer is: you can't. — biziclop, Mar 19 '12 at 20:26

score 4 · Accepted Answer · answered Mar 19 '12 at 20:15

This isn't working like you expect because the return value of roundTwoDecimals() is of type double, which discards the formatting you do within the function. In order to achieve what you want, you might consider returning the String representation from roundTwoDecimals() instead.

Jakub Zaverka · Answer 2 · 2012-03-19T20:27:02.190

0

Converting formatted number back to double will make you lose all formatting changes. Change the function to:

public static String roundTwoDecimals(double d) {   
    DecimalFormat twoDForm = new DecimalFormat("#.00");
    return twoDForm.format(d);
}

EDIT: you were right, "#.00" is correct.

edited Mar 19 '12 at 20:27

answered Mar 19 '12 at 20:16

Jakub Zaverka

8,574
3
28
47

Actually, `#.##` would make the decimal places optional, which doesn't seem to be what he wants. The advice about returning the `String` is the relevant part. – VeeArr Mar 19 '12 at 20:21

Rounding Double in Java - Minimum Decimal Places

2 Answers2