Java Examples: Round doubles to the nth decimal

Question:

How can you round doubles to the nth decimal?

Answer:

For 5 digits precision:

   (double)Math.round(value * 100000) / 100000

The number of zeros indicate the number of decimals.

Code:

public class Rounding {
   public static void main(String[] args) {
 
      double pi = 3.14159265359;
      System.out.println(pi);
 
      System.out.println( Math.round(pi) );
      System.out.println( (double)Math.round(pi*10)/10 );
      System.out.println( (double)Math.round(pi*100)/100 );
      System.out.println( (double)Math.round(pi*1000)/1000 );
      System.out.println( (double)Math.round(pi*10000)/10000 );
      System.out.println( (double)Math.round(pi*100000)/100000 );
      System.out.println( (double)Math.round(pi*1000000)/1000000 );
      System.out.println( (double)Math.round(pi*10000000)/10000000 );
 
   }
}

Output:

$ java Rounding 
3.14159265359
3
3.1
3.14
3.142
3.1416
3.14159
3.141593
3.1415927