Convert String to double with two digits

Question

How can I format "String" type of numbers (eg. 199.0, or 199) to return a "double" type of nubmers like 199.00, or 199.00. It should have two digits.
For example, the input is String of 199.0, how can I get "double" 199.00. Always format as two digits.
Thanks for your help,

Answer 1

Thanks for replying.
Here is my code. For some reason, when convert the returned String back to double in main, it cut the "0".
What's wrong with my code? How can I get that 4.60 in double type.
Thanks again,
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import java.text.*;
import java.util.*;
import java.sql.*;
public class NumUtils
// Convert Double to 99.99
public static String format(String str)
//double d = 4.6;
double d = Double.parseDouble(str);
NumberFormat formatter = new DecimalFormat("0.00");
formatter.setMaximumFractionDigits(2);
String s = formatter.format(d);
return s;
public static void main(String[] args)
String myDouble = "4.6";
String mynewdouble = format(myDouble);
System.out.println(" --- formatDouble = " + mynewdouble);
double my_d = Double.parseDouble(mynewdouble);
System.out.println(" --- Double = " + my_d);