. symbol indicates the decimal point

import java.text.DecimalFormat;
import java.text.NumberFormat;

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

    NumberFormat formatter = new DecimalFormat(".00");
    String s = formatter.format(-.567); 
    System.out.println(s);
    
    s = formatter.format(-1231231.567); 
    System.out.println(s);
    
    s = formatter.format(-12312312.5); 
    System.out.println(s);
  }
}

-.57
-1231231.57
-12312312.50