The number of #'s to the left of the decimal point sets the multiple of the exponent. : Decimal « Data Type « Java Tutorial

1. Java Tutorial
2. Data Type
3. Decimal

import java.text.DecimalFormat;

public class Main {
  public static void main(String[] argv) throws Exception {

    DecimalFormat formatter = new DecimalFormat("#E0"); // exponent can be any
                                                        // value
    String s = formatter.format(-1234.567); 
    System.out.println(s);
    
    s = formatter.format(-.1234567); 
    System.out.println(s);
  }
}
//-.1E4
//-.1E0