Numbers and Dates - Java 8 Recipes - page 98

public static void formatDouble(double myDouble){
NumberFormat numberFormatter = new
DecimalFormat("##.000");
String result = numberFormatter.format(myDouble);
System.out.println(result);
}
For instance, if the double value passed into the formatDouble() method is
345.9372 , the following will be the result:
345.937
Similarly, if the value .7697 is passed to the method, the following will be the res-
ult:
.770
Each of the results is formatted using the specified pattern and then rounded ac-
cordingly.
How It Works
The DecimalFormat class can be used along with the NumberFormat class to
round and/or format double or long values. NumberFormat is an abstract class
that provides the interface for formatting and parsing numbers. This class provides the
ability to format and parse numbers for each locale, and obtain formats for currency,
percentage, integers, and numbers. By itself, the NumberFormat class can be very
useful as it contains factory methods that can be used to obtain formatted numbers. In
fact, little work needs to be done in order to obtain a formatted string. For example, the
following code demonstrates calling some factory methods on the NumberFormat
class:
// Obtains an instance of NumberFormat class
NumberFormat format = NumberFormat.getInstance();
// Format a double value for the current locale
String result = format.format(83.404);
System.out.println(result);