class MessageFormat

Constructs messages from a pattern and parameters. A message format takes a list of arguments, formats them, and inserts them into the pattern at specific places.

Replacement tokens are delimited with curly braces. Tokens begin with an integer, which determines the format parameter that is inserted in place of the token. The following tokens are supported where n is the zero-based parameter index:

• {n} — Replaced with the nth parameter. The formatting of the nth parameter, param, depends on its data type:
  • null — "null"
  • string — param
  • number — {n,number}
  • Object — param.toString()
  • Date — {n,datetime,short}
  • Not provided — "{n}"
• {n,date} — Formats the nth parameter as a date with the default format length (medium).
• {n,date,[short|medium|long|full|format]} — Formats the nth parameter as a date according to the specified format length or an arbitrary date format.
• {n,time} — Formats the nth parameter as a time with the default format length (medium).
• {n,time,[short|medium|long|full|format]} — Formats the nth parameter as a time according to the specified format length or an arbitrary date format.
• {n,datetime} — Formats the nth parameter as a date/time with the default format length (medium).
• {n,datetime,[short|medium|long|full|format]} — Formats the nth parameter as a date/time according to the specified format length or an arbitrary date format.
• {n,number} — Formats the nth parameter as a number with the default number format.
• {n,number,[integer|percent|currency|format]} — Formats the nth parameter as a number according to the specified number format type or an arbitrary number format.

The formatting of date, time, datetime, and number tokens depends on the locale of the message format. The formats used to format such tokens inherit their locale from the message format. If no locale is passed to the message format constructor, the default system locale is used.

Within a format, single quotes (') delimit quoted sequences that are not parsed for tokens. Therefore, in order to insert a curly bracket in a message format, it should be surrounded by single quotes: new MessageFormat("A curly bracket: '{'"). To insert a single quote character, use two single quotes in succession: new MessageFormat("A single quote: ''").