Java Magic Hall: A tentative study of Messageformat.format

First, preface

When I started to move from. NET to Java, I always feel that String.Format is not used to it, I hope the format template will be {0}, this is {1 }'s cat.{ 1},this is {0}' s dog. Instead of the%1$s , this is the%2$s's cat.%2$s,this is%1 $ s 's dog. 。 Later found that Java.text.MessageFormat.format can meet my small wish.

Second, static method Java.text.MessageFormat.format

Method definition:

String Messageformat.format (String fmt, Object...args)

Enter the FMT as the Messageformat mode parameter.

Three, Messageformat mode

Format: Argumentindex[,formattype[,formatstyle]]

Argumentindex , which is the index of the entry position starting at 0.

formattype , specifies that the incoming parameter is formatted with a different format subclass. The value range is as follows:

Number: Call NumberFormat to format

Date: Call DateFormat for formatting

Time: Call DateFormat to format

Choice: Call Choiceformat to format

formattype , sets the formatting style used in Formattype. The value range is as follows:

Short,medium,long,full,integer,currency,percent,subformpattern (sub-format pattern, shaped like #.##)

Note: formattype and Formatstyle are mainly used for formatting dates, numbers, percentages, and so on.

Example--format the number 1.23 as 1.2:

Double 1.23  = Messageformat.format ("{0,number,#.#}", num);

Iv. Messageformat points of attention

1. Two single quotes represent a single quotation mark, and only one single quotation mark is ignored.

2. Single quotation marks invalidate the placeholders that follow them, resulting in a direct output placeholder.

Messageformat.format ("{0}{1}"12//  results Messageformat.format ("' {0}{1}"12//  result {0}{1} Messageformat.format ("' {0} ' {1}"12// result {0}

So it can be used to output left curly braces (single-write left curly braces will error, while single-write right curly brackets will output normally)

Messageformat.format ("' {' {0}}"2//  result {2

So the example in the preface should be written as

{0 This is {1}'s cat. {1}, This is {0}'s dog.

V. Class-Level relationships

|--Java.text.MessageFormat

Top level abstract class java.text.format-| |--java.text.choiceformat

|--java.text.numberformat-|

| |--java.text.decimalformat

|

|--java.text.dateformat-java.text.simpledateformat

Vi. Performance Issues

Because the static method Messageformat.format Internal is

 Public Static string Format (string pattern, Object ... arguments)   {      new  Messageformat (pattern);       return Temp.format (arguments);  }  

Therefore, to format a string of the same pattern multiple times, it is better to create a Messageformat instance that performs a formatting operation.

Vii. Summary

For simple formatting or string assembly, the Messageformat.format method is more convenient to use, but to format more rich words if you use the String.Format method !

Respect the original, reprint please indicate from: http://www.cnblogs.com/fsjohnhuang/p/4095059.html ^_^ Fat Boy John

Viii. Reference　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

http://zqc-0101.iteye.com/blog/114014

Java Magic Hall: A tentative study of Messageformat.format