Convert double to 2 decimal places?

Hi,

Am trying to calculate the volume using 2 variables both of which are in cm and the requirement is to display in inches.

Code:

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length = cl.getUserLength();
diam = cd.getUserDiameter();
     
volume = ((diam / 2) * length) / 2.54;

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Both length and diam can only be entered in as whole numbers.
Thats my code so far. (diam / 2) is to get the radius and / 2.54 is to get it to inches. However for example if both measurements are say 10, i get a output of 19.68503937007874

I want it down to 2 decimal places. I have checked alot online and references to BigDecimal and DecimalFormat, however tutorials are very unclear on how to implement.

All help will be appreciated.

If you are going to be displaying the number on the console / standard output stream, then using System.out.printf should do the trick. Since a double is a floating point number, you can use something like %.2f as the format specifier to format your String.

For more on how to use this, please look here: formatting. Note that System.out.format works the same way as System.out.printf.

I agree with Fubarable: what you are trying to do is format a value for display rather than convert the value into something else (of necessity, less accurate).

You learn something here every day!

Quote:

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I want it down to 2 decimal places.

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I was worried that you choose a conversion factor of 2.54 which only has 3 significant places and, depending on the absolute magnitude of length and diam I thought there might be a problem. It turns out that 2.54 is accurate to umpteen decimal places: but only since 1959 when the "international foot" was invented and carefully aligned with metric units. A "survey foot" in the US is 12 inches each of 2.54000508cm.