How to round a decimal output to two places?

Question

In this program I'm printing a value from a calculation of type double to the screen.But at present the calculation is giving 14 decimal places.My question is,is there a facility in Java to wrap the output statement in that could specify the amount of decimal places?For example round(mark1,2)

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The way it is printed at present is like this:

 double markOne = intent.getDoubleExtra("number1", 0);
 result1.setText(String.valueOf(markOne)+"mm");

Is it possible to wrap the setText in a Java method or would I have to create a custom format?Could someone give me an example of this with my code? Thanks

score 9 · Accepted Answer · answered Dec 17 '13 at 16:57

9

You could use a decimal formatter

DecimalFormat df = new DecimalFormat("#.##");
System.out.print(df.format(d));

answered Dec 17 '13 at 16:57

Amir Afghani

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thanks,I'm just going to test now like this: `DecimalFormat df = new DecimalFormat("#.##"); result1.setText(String.valueOf(df.format(markOne)+"mm"));` – Brian J Dec 17 '13 at 17:50
That worked a charm,I was getting a lot of suggestions for convoluted custom methods earlier,when all I had to do was use `DecimalFormat` – Brian J Dec 17 '13 at 17:55

score 2 · Answer 2 · answered Dec 17 '13 at 17:04

2

I think it's better to use BigDecimal type instead of Double. You could do

BigDecimal myValue= new BigDecimal(12.3577);
  myValue= myValue.setScale(2, BigDecimal.ROUND_HALF_UP);

And myValue will be 12.36

I hope this will help

answered Dec 17 '13 at 17:04

Pracede

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+1 for using Rounding modes and BigDecimal to do proper rounding – Dev Blanked Dec 17 '13 at 17:10
@Pracede How do I apply this to my code,I'm a bit confused? – Brian J Dec 17 '13 at 17:43

score 0 · Answer 3 · edited Dec 17 '13 at 16:58

0

Try this:

  int decimalPlaces = 2;
    markOne = double(int(markOne*Math.pow(10, decimalPlaces)))/Math.pow(10, decimalPlaces);

edited Dec 17 '13 at 16:58

Nikola Despotoski

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answered Dec 17 '13 at 16:56

Karasu

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Now you're just being fancy. – But I'm Not A Wrapper Class Dec 17 '13 at 17:00

How to round a decimal output to two places?

3 Answers3