Rounding a decimal in Java

Question

I created a program that calcuates the average acceleration using 3 inputs. Here's my code:

    Scanner input = new Scanner(System.in);

    System.out.print("Enter v0, V1, and t:  ");
    double v0 = input.nextDouble();
    double v1 = input.nextDouble();
    double t = input.nextDouble();

    double acceleration = (v1 - v0) / t;

    System.out.println("The average acceleration is " + acceleration);

Here's the output:

Enter v0, V1, and t: 5.5 50.9 4.5
The average acceleration is 10.088888888888889

Here's the expected output:

Enter v0, V1, and t: 5.5 50.9 4.5
The average acceleration is 10.0889

I'm not quite sure how to trim the excess 8's in my code. I tried casting acceleration into a float and that somewhat works, but there is still too many 8s with it.

http://stackoverflow.com/questions/153724/how-to-round-a-number-to-n-decimal-places-in-java — marsh, Sep 17 '14 at 16:27
does the number simply need to *print* that many decimal places, or do you want to actually reduce the precision of the variable? — Woodrow Barlow, Sep 17 '14 at 16:28

score 3 · Answer 1 · answered Sep 17 '14 at 16:27

You can use decimal format class like this

import java.text.DecimalFormat;

public class Tests {
 public static void main (String args []) {

     double d = 10.088888888888889;

     DecimalFormat decimalFormat = new DecimalFormat("00.0000");

     System.out.println(decimalFormat.format(d));
 }
 }

Rounding a decimal in Java

1 Answers1