使用DecimalFormat Grouping Java时删除最后一个分组分隔符

Question

I want to format lengthy double numbers in my android calculator app
2 problems ... First is that I want to enable Grouping by 3 so 1200 would be shown 1,200 . But for numbers like 1000 what I get is 1,
How can I get 1,000 for result ?

also another problem is that I want Results with up to 25 integer digits and 4 decimal fraction digits ... but even though I set Decimalformat maximum to 25, after number of integers surpasses 18, Digits turn to be zeros. for example what I want is
1,111,111,111,111,111,111,111,111
but I get
1,111,111,111,111,111,110,000,000,
Here's the code

 DecimalFormat df = new DecimalFormat();
    df.setMaximumFractionDigits(4);
    df.setMaximumIntegerDigits(25);
    df.setGroupingUsed(true);
    df.setGroupingSize(3);
    String formatted = df.format(mResultBeforeFormatting);

what pattern should I use ?

Answer 1

Ok so for others who face this problem like me for first part best pattern was

 DecimalFormat df = new DecimalFormat("###,##0.####");

for second problem as "x-code" noted it apears there's no hope using double . should try using BigDecimal

Answer 2

I found answers to both parts of the question right here on StackOverflow.

First is that I want to enable Grouping by 3

Here are several solutions to the grouping problem.

another problem is that I want Results with up to 25 integer digits

In this case what's really happening is that Java doubles can't represent 25 decimal digits .

For this problem you might want to look at the BigDecimal class, which can represent the numbers in your example.