Use a Formatter object to format 20 random values of type double between –50 and +50

Use a Formatter object to format 20 random values of type double between –50 and +50 and output the entire set of 20 in a single call of System.out.print() or System.out.println().

import java.util.Formatter;
import static java.lang.Math.random;

public class FormatToString {
  public static void main(String[] args) {
    double[] data = new double[20];

    for (int i = 0 ; i < data.length ; ++i) {
      data[i] = 100.0*random() - 50.0;
    }

    StringBuilder buf = new StringBuilder();          // Buffer to hold output
    Formatter formatter = new Formatter(buf);         // Formatter to format data into buf
    int i = 0;
    for(double x : data) {
      formatter.format("%4d)%+7.2f", ++i, x);
      if(i%5 == 0) {
        formatter.format("%n");
      }
    }
    System.out.println(buf);                          // Output all the values in one go
  }
}

Output of Above Java Program

   1) +46.53   2)  -5.14   3)  -3.81   4) -45.54   5) +32.27
   6) -23.71   7) +47.19   8) +44.52   9) -19.52  10) -35.47
  11)  -9.32  12) -28.05  13) +44.03  14) -46.65  15)  -5.68
  16) +46.42  17)  -8.72  18) -13.47  19) -44.96  20) +46.57