Java in a Nutshell, 5th Edition

Name

MessageFormat

Synopsis

This class formats and substitutes objects into specified positions in a message string (also known as the pattern string). It provides the closest Java equivalent to the printf( ) function of the C programming language. If a message is to be displayed only a single time, the simplest way to use the MessageFormat class is through the static format( ) method. This method is passed a message or pattern string and an array of argument objects to be formatted and substituted into the string. If the message is to be displayed several times, it makes more sense to create a MessageFormat object, supplying the pattern string, and then call the format( ) instance method of this object, supplying the array of objects to be formatted into the message.

The message or pattern string used by the MessageFormat contains digits enclosed in curly braces to indicate where each argument should be substituted. The sequence "{0}" indicates that the first object should be converted to a string (if necessary) and inserted at that point, while the sequence "{3}" indicates that the fourth object should be inserted. If the object to be inserted is not a string, MessageFormat checks to see if it is a Date or a subclass of Number. If so, it uses a default DateFormat or NumberFormat object to convert the value to a string. If not, it simply invokes the object’s toString( ) method to convert it.

A digit within curly braces in a pattern string may be followed optionally by a comma, and ...