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Need Help Rounding

Posted on 2011-09-30
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Last Modified: 2012-05-12
I need help with a rounding problem. I want to take a number and convert it with two decimal places.

For instance, 345.667 would end up being 345.67; and 345 would end up being 345.00.

I have the following:

double number = Marth.round(number * 100.0)/100.0;

This works for most numbers, but when I have a whole number it converts it 345.0 with only one decimal place.

Any suggestions?
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Question by:InquisitiveProgrammer
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LVL 47

Expert Comment

by:for_yan
ID: 36895498

something like that:



DecimalFormat f = new DecimalFormat("#####.##");

double d = 345.6789;
String s = f.format(d);
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LVL 47

Expert Comment

by:for_yan
ID: 36895507

This does what you want:

        DecimalFormat fff = new DecimalFormat("#####.00");
        System.out.println(fff.format(345.6789));
        System.out.println(fff.format(365.0));

Open in new window


345.68
365.00

Open in new window

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LVL 47

Expert Comment

by:for_yan
ID: 36895510
More examples:

 DecimalFormat fff = new DecimalFormat("#####.00");
        System.out.println(fff.format(345.6789));

               System.out.println(fff.format(365.0));

        System.out.println(fff.format(365));

Open in new window



Output:

345.68
365.00
365.00

Open in new window

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Author Comment

by:InquisitiveProgrammer
ID: 36895512
Is there no way to keep the number as a double? Without converting to string?
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Expert Comment

by:for_yan
ID: 36895522
What you are asking in fact applies to strings - for double number there is no difference between

double d = 365;

double d = 365.0;

double d = 365.00;

those are all the same double - it is hen you want to print them where the difference come.

You of course can say


double d = Double.parseDouble(fff.format(345));

but it does not make much sense - if you could explain in  what context you mmay need it

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LVL 47

Expert Comment

by:for_yan
ID: 36895529
your rounding will work in the sense of giving number with no more that two digits

double number = Marth.round(number * 100.0)/100.0;

but when you apply it to number with less decimal digits - I don't see where is the program unless you want to print it
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LVL 47

Expert Comment

by:for_yan
ID: 36895530
but when you apply it to number with less decimal digits - I don't see where is the problem unless you want to print it
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LVL 1

Author Comment

by:InquisitiveProgrammer
ID: 36895538
I'm not getting the decimals to print out correctly.

Here is my function:

 
public String roundTwoDecimals(double number) {
    	number = Math.round(number * 100.0)/100.0;
    	DecimalFormat twoDecForm = new DecimalFormat("###############.##");
    	String dollarAmount = twoDecForm.format(number);
    	//return Double.valueOf(twoDecForm.format(number));
    	return dollarAmount;
    }

Open in new window


This will work if I have a number like 34.5677, but it still won't work for when I have a number like 64 or 54.6
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Accepted Solution

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for_yan earned 500 total points
ID: 36895542
you should have format "#####.00" - see my tested example
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