formatted output for Java
A method to format the output requires a format string and a parameter list (arguments). The format string may include the determined text (fixed text) and one or more format specifiers (formatted specifier). Look at the following example:
String S=string.format ("Duke ' s Name:%s", Name);//format (string format,object arguments)
This is the format method of the Java string class, in which "Duke's Name:%s" is the first parameter of this method, that is, the format string, where (%s) is the format specifier, except that the remainder is the determined text. Name is the parameter list (arguments).
• for the general case, the syntax for the format specifier is as follows :
%[argument_index$][flags][width][.precision]conversion
• The format specifier starts with a% symbol and is replaced with the corresponding parameter. (% symbol can be based on \ Understand, to output the% symbol, the format needs to write such a percent)
Argument_index is a decimal integer, as the name implies, that represents the position of the following argument, such as the 1$ above for name.
flags is used to control the output format, but specifically how to control the end of the conversion (conversion).
width is a positive integer that indicates the length of the character to be output.
Conversion character
Sign
• Code:
Public class formatdemo { Public static void main (string[] args) { // TODO auto-generated method stub System. out. println ("Hello World"); Double x=-10000.0/3.0; double y=5000.0/3.0; System. out. println (x); System. out. printf ("%,10.2f\r\n",x); System. out. printf ("%-,10.2f\r\n",x); system. out .printf ( "%+ (, 10.2f%2$.3f\r\n" ,x , y System. out. printf ("%+ (, 10.2f%1$.3f%2$.3f%<f%<.3f\r\n",x,y); } } |
• Results:
• Date format conversion:
The format specifier feature of the date is that the conversion in the descriptor is started by T, plus any character in the following table ends.
Time is expressed as a number of milliseconds (positively negative) from a fixed point in time, which is the so-called epoch (epoch), which is the abbreviation for UTC time of January 1, 1970 00:00:00.UTC is coordinated Universal. Same as GMT (Greenwich Mean time/GMT). Java separates the saved time from the name of the point-in-time. The date class is used to represent the point in time, and the other is the Hitachi notation Calendar class.
From "Java Core technology Volume I"
Formatted output for Java