How to use Java's DecimalFormat for “smart” cu

问题:

I'd like to use Java's DecimalFormat to format doubles like so:

#1 - 100 -> $100
#2 - 100.5 -> $100.50
#3 - 100.41 -> $100.41

The best I can come up with so far is:

new DecimalFormat("'$'0.##");

But this doesn't work for case #2, and instead outputs "$100.5"

Edit:

A lot of these answers are only considering cases #2 and #3 and not realizing that their solution will cause #1 to format 100 as "$100.00" instead of just "$100".

回答1:

Does it have to use DecimalFormat?

If not, it looks like the following should work:

String currencyString = NumberFormat.getCurrencyInstance().format(currencyNumber);
//Handle the weird exception of formatting whole dollar amounts with no decimal
currencyString = currencyString.replaceAll("\\.00", "");

回答2:

Use NumberFormat:

NumberFormat n = NumberFormat.getCurrencyInstance(Locale.US); 
double doublePayment = 100.13;
String s = n.format(doublePayment);
System.out.println(s);

Also, don't use doubles to represent exact values. If you're using currency values in something like a Monte Carlo method (where the values aren't exact anyways), double is preferred.

See also: Write Java programs to calculate and format currency

回答3:

Try

new DecimalFormat("'$'0.00");

Edit:

I Tried

DecimalFormat d = new DecimalFormat("'$'0.00");

        System.out.println(d.format(100));
        System.out.println(d.format(100.5));
        System.out.println(d.format(100.41));

and got

$100.00
$100.50
$100.41

回答4:

Try using

DecimalFormat.setMinimumFractionDigits(2);
DecimalFormat.setMaximumFractionDigits(2);

回答5:

You can check "is number whole or not" and choose needed number format.

public class test {

  public static void main(String[] args){
    System.out.println(function(100d));
    System.out.println(function(100.5d));
    System.out.println(function(100.42d));
  }

  public static String function(Double doubleValue){
    boolean isWholeNumber=(doubleValue == Math.round(doubleValue));
    DecimalFormatSymbols formatSymbols = new DecimalFormatSymbols(Locale.GERMAN);
    formatSymbols.setDecimalSeparator('.');

    String pattern= isWholeNumber ? "#.##" : "#.00";    
    DecimalFormat df = new DecimalFormat(pattern, formatSymbols);
    return df.format(doubleValue);
  }
}

will give exactly what you want:

100
100.50
100.42

回答6:

You can use the following format:

DecimalFormat dformat = new DecimalFormat("$#.##");

回答7:

I know its too late. However following worked for me :

DecimalFormatSymbols otherSymbols = new DecimalFormatSymbols(Locale.UK);
new DecimalFormat("\u00A4#######0.00",otherSymbols).format(totalSale);

 \u00A4 : acts as a placeholder for currency symbol
 #######0.00 : acts as a placeholder pattern for actual number with 2 decimal 
 places precision.   

Hope this helps whoever reads this in future :)

回答8:

You can try by using two different DecimalFormat objects based on the condition as follows:

double d=100;
double d2=100.5;
double d3=100.41;

DecimalFormat df=new DecimalFormat("'$'0.00");

if(d%1==0){ // this is to check a whole number
    DecimalFormat df2=new DecimalFormat("'$'");
    System.out.println(df2.format(d));
}

System.out.println(df.format(d2));
System.out.println(df.format(d3));

Output:-
$100
$100.50
$100.41

回答9:

printf also works.

Example:

double anyNumber = 100; printf("The value is %4.2f ", anyNumber);

Output:

The value is 100.00

4.2 means force the number to have two digits after the decimal. The 4 controls how many digits to the right of the decimal.