To show negative numeric output inside parentheses, rather than with a leading -, use the '(' flag : Formatter Flags « Development « Java Tutorial

1. Java Tutorial
2. Development
3. Formatter Flags

import java.util.Formatter;

public class MainClass {
  public static void main(String args[]) {
    Formatter fmt = new Formatter();

    fmt.format("%(d", -100);
    System.out.println(fmt);

  }
}

(100)