Format floating point with Java MessageFormat

To format message with floating point fillers in Java, we use the MessageFormat class. The MessageFormat class gives us a way to produce concatenated messages which are not dependent on the language. The MessageFormat class extends the Serializable and Cloneable interfaces.

Declaration −The java.text.MessageFormat class is declared as follows −

public class MessageFormat extends Format

The MessageFormat.format(pattern, params) method formats the message and fills in the missing parts using the objects in the params array matching up the argument numbers and the array indices.

The format method has two arguments, a pattern and an array of arguments. The pattern contains placeholder in {} curly braces which have a index that indicate the position in the array where the value of the argument is stored, a number argument indicating that the filler is a number and a #.# parameter indicating that the number is a floating point number. They are as follows −

MessageFormat.format("{0,number,#.#} Hellos and {1,number,#.#} Worlds", obj);

Let us see a program to format the message with floating fillers:

Example

 Live Demo

import java.text.MessageFormat;
public class Example {
   public static void main(String[] args) throws Exception {
      Object[] obj = new Object[] { new Float(23.21), new Float(56.86) };
      String message = MessageFormat.format("{0,number,#.#} Hellos and {1,number,#.#} Worlds", obj);
      System.out.println(message);
   }
}

Output

23.2 Hellos and 56.9 Worlds

Note that the Floating numbers have been rounded off one significant digit i.e. 23.21 has been rounded off to 23.2 and 56.86 has been rounded off to 56.9 −

Object[] obj = new Object[] { new Float(23.21), new Float(56.86) };