Negative sign in case of zero in java

Question

Is there any way to truncate the negative sign when the result returns zero; while using decimal format?

DecimalFormat df = new DecimalFormat("#,##0.0");
df.setRoundingMode(RoundingMode.HALF_UP);
formattedValue = df.format("-0.023");

The above code returns -0.0 . Is there any way by which it will return only 0.0? However, I want to retain the negative sign when the result is a negative number.

I get an error: Cannot format given Object as a Number. You should use the value -0.023 not the string "-0.023" — Nir Alfasi
– Nir Alfasi, Commented Aug 13, 2012 at 6:28

Bohemian · Accepted Answer · 2019-05-30 08:52:39Z

26

I don't think there's a way of doing it just with DecimalFormat, but this one-liner takes care of the problem:

formattedValue = formattedValue.replaceAll( "^-(?=0(\\.0*)?$)", "");

It removes (replaces with "") the minus sign if it's followed by 0-n characters of "0.00000...", so this will work for any similar result such as "-0", "-0." or "-0.000000000"

Here's some test code:

public static void main(String[] args) {
    System.out.println(format(-0.023));
    System.out.println(format(12.123));
    System.out.println(format(-12.345));
    System.out.println(format(-0.123));
    System.out.println(format(-1.777));
}

public static String format(double number) {
    DecimalFormat df = new DecimalFormat("#,##0.0");
    df.setRoundingMode(RoundingMode.HALF_UP);
    String formattedValue = df.format(number);
    formattedValue = formattedValue.replaceAll("^-(?=0(\\.0*)?$)", "");
    return formattedValue;
}

Output (as expected):

0.0
12.1
-12.3
-0.1
-1.8

edited May 30, 2019 at 8:52

answered Aug 13, 2012 at 7:12

Bohemian♦

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5 Comments

Mihai Over a year ago

In case you are using a currency formatter with the currency symbol in front of the zero you may want to change the regex to "^-(?=\D*0(.0*)?$)" (notice the \D* which will match any non digit characters zero or more times) This should match strings like: -$0

Dr.jacky Over a year ago

By any chance, can you give us the regex in Kotlin language as well? It didn't work on Kotlin and still getting -0

Bohemian Over a year ago

@Dr.jacky AFAIK Kotlin is syntactic sugar over java, so it should work as is. Check how you’re coding/using the regex. Can you post your code?

jackes Over a year ago

There are many countries using comma "," as a decimal separator. You may want to handle this case also: "^-(?=0([.,]0*)?$)".

Bohemian Over a year ago

@jackes why not include Arabic and Hindi numerals too? This code is an approach that shows a technique that can be adapted to a specific situation, not a lasting global specification.

Nandkumar Tekale · Accepted Answer · 2012-08-13 06:53:10Z

5

I think this would be a workaround to avoid -0.0. Use following code :

DecimalFormat df = new DecimalFormat("#,##0.0");
df.setRoundingMode(RoundingMode.HALF_UP);       
df.setNegativePrefix(""); // set negative prefix BLANK
String formattedValue = df.format(-0.023);
df.setNegativePrefix("-"); // set back to - again
System.out.println(formattedValue);

Output :

0.0

edited Aug 13, 2012 at 6:53

answered Aug 13, 2012 at 6:43

Nandkumar Tekale

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2 Comments

Pravat Over a year ago

Well I have put the above code in a utility method. Though it works for 0.0; it does not work for other negative numbers where I need to retain the -ve sign. resetting the negative prefix does not have any effect as every time the DecimalFormat instance is created.

Nandkumar Tekale Over a year ago

You should not put workarounds in your utility classes. Let it be there where you are using it and keep it marked with markers like // FIXME. So next time if you find better solution you can implement that. I reset Negative Prefix above with intention, if you are going to use df instance again for different numbers. If you are going to use new instance then it is not necessary.

Sujay · Accepted Answer · 2012-08-13 06:31:46Z

Try this: DecimalFormat df = new DecimalFormat("#,##0.0#;(#,##0.0#)");

According to the Javadoc for DecimalFormat:

A DecimalFormat pattern contains a positive and negative subpattern, for example, "#,##0.00;(#,##0.00)". Each subpattern has a prefix, numeric part, and suffix. The negative subpattern is optional; if absent, then the positive subpattern prefixed with the localized minus sign ('-' in most locales) is used as the negative subpattern. That is, "0.00" alone is equivalent to "0.00;-0.00". If there is an explicit negative subpattern, it serves only to specify the negative prefix and suffix; the number of digits, minimal digits, and other characteristics are all the same as the positive pattern. That means that "#,##0.0#;(#)" produces precisely the same behavior as "#,##0.0#;(#,##0.0#)".

BolBol · Accepted Answer · 2012-08-13 06:36:09Z

1

That by check if the calculated value = "-0.0" make it equal "0.0"

and you can capsulate the code sush as

public String getFormattedValue(String input) {
        DecimalFormat df = new DecimalFormat("#,##0.0");
        df.setRoundingMode(RoundingMode.HALF_UP);
        String formattedValue = df.format(input);

        if (formattedValue.equalsIgnoreCase("-0.0")) {
            formattedValue = "0.0";
        }

        System.out.println(formattedValue);
        return formattedValue;
    }

answered Aug 13, 2012 at 6:36

BolBol

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1 Comment

Pravat Over a year ago

This works but, becomes an explicit check. Won't work if the value is -0.00 etc.

jolivier · Accepted Answer · 2017-03-27 12:32:04Z

1

I find the -0 quite useful because it informs you that the rounded value was in fact negative (which can have a lot of meaning for some functions). The only issue for me is that -1 * 0 is actually really 0 and should be formatted as 0 although it isn't with Java formatters.

The following formatter takes care of that, without the expensive cost of String manipulation (especially RegExps):

public static String formatWithoutMinusZeroIssue(double d, DecimalFormat yourFormatter) {
    if (d == 0) {
        return yourFormatter.format(0);
    } else {
        return yourFormatter.format(d);
    }
}

This uses the fact that although -1 * 0 and 0 are formatted differently, they are equal.

answered Mar 27, 2017 at 12:32

jolivier

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Comments

subes · Accepted Answer · 2020-01-17 13:44:06Z

Faster and works with arbitrary precision (also supports suffixes to ignore e.g. currencies, put 0 for no suffix):

public static String normalizeNegativeZero(final String str, final int skipSuffixLength) {
    if (str.length() > 3 && str.charAt(0) == '-' && str.charAt(1) == '0'
            && (str.charAt(2) == '.' || str.charAt(2) == ',')) {
        for (int i = 3; i < str.length() - skipSuffixLength; i++) {
            if (str.charAt(i) != '0') {
                return str;
            }
        }
        return StringUtils.removeStart(str, "-");
    } else {
        return str;
    }
}

Here the Testcases:

Assertions.assertThat(normalizeNegativeZero("-0.00000", 0)).isEqualTo("0.00000");
Assertions.assertThat(ScaledDecimalToStringBuilder.normalizeNegativeZero("-0.00001", 0)).isEqualTo("-0.00001");

Assertions.assertThat(normalizeNegativeZero("-0.00000EUR", "EUR".length())).isEqualTo("0.00000EUR");
Assertions.assertThat(normalizeNegativeZero("-0.00001EUR", "EUR".length())).isEqualTo("-0.00001EUR");

Dr.jacky · Accepted Answer · 2019-07-01 14:22:43Z

-1

The Kotlin version of Bohemian's answer:

fun Double.formatAmount(): String {
    val ds = DecimalFormatSymbols()
    ds.decimalSeparator = '.'
    ds.groupingSeparator = ','
    val df = DecimalFormat("#,##0.##", ds)
    df.roundingMode = RoundingMode.DOWN
    var formattedDouble = df.format(this)
    formattedDouble = formattedDouble.replace("^-(?=0(\\\\.0*)?\$)".toRegex(), "")
    return formattedDouble
}

answered Jul 1, 2019 at 14:22

Dr.jacky

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