New formatted output of JDK5 new features

JDK5.0 allows you to format the output directly using the printf () method as C, and provides a number of parameters to format the input, and the invocation is simple:

System.out.format ("Pi is approximately%f", Math.PI);

System.out.printf ("Pi is approximately%f", Math.PI);

The printf () and format () methods have the same functionality. System.out is an example of Java.io.PrintStream. PrintStream, Java.io.PrintWriter, and java.lang.String each class has four new formatting methods:

Format (String format, Object ... args);

printf (String format, Object ... args);

Format (Locale Locale, String format, Object ... args);

printf (Locale Locale, String format, Object ... args);

At the same time, the previous formatter class also provides a more sophisticated way to format, for example:

Formatter.format ("Pi is approximately%1$f," +

"and E is about%2$f", Math.PI, MATH.E);

The formatting elements are composed as follows:

%[argument_index$][flags][width][.precision]conversion

which

Argument_index is a positive integer that shows the position of the parameter, 1 is the first argument

Width represents the minimum number of letters for the output

Precision represents the number of decimal places

Conversion represents the type of the parameter being formatted:

F Float,

T time

D Decimal

o Octal

x hexadecimal

S General

c a Unicode character

Here's an example:

Package format;

Import Java.util.Formatter;

public class Usingformatter {

public static void Main (string[] args) {

if (args.length!= 1) {

System.err.println ("Usage:" +

"Java Format/usingformatter");

System.exit (0);

}

String format = args[0];

StringBuilder StringBuilder = new StringBuilder ();

Formatter Formatter = new Formatter (StringBuilder);

Formatter.format ("Pi is approximately" + format +

", and E is about" + format, Math.PI, MATH.E);

System.out.println (StringBuilder);

}

}

Console call

Java format/usingformatter%f

Output

Pi is approximately 3.141593, and E is about 2.718282

Console call

Java format/usingformatter%.2f

Output

Pi is approximately 3.14, and E is about 2.72

Console call

Java format/usingformatter%6.2f

Output (with space to fill the length)

Pi is approximately 3.14, and E is about 2.72

Console call

Java format/usingformatter%1$.2f

Output

Pi is approximately 3.14, and E is about 3.14

Change Regional Settings

Package format;

Import Java.util.Formatter;

Import Java.util.Locale;

public class Usingformatter {

public static void Main (string[] args) {

if (args.length!= 1) {

System.err.println ("Usage:" +

"Java format/usingformatter <format string>");

System.exit (0);

}

String format = args[0];

StringBuilder StringBuilder = new StringBuilder ();

Formatter Formatter = new Formatter (StringBuilder,

Locale.france);

Formatter.format ("Pi is approximately" + format +

", and E is about" + format, Math.PI, MATH.E);

System.out.println (StringBuilder);

}

}

Console call

Java format/usingformatter%.2f

Output

Pi is approximately 3,14, and e are about 2,72

Using format,printf to replace the method

Package format;

public class Usingsystemout {

public static void Main (string[] args) {

if (args.length!= 1) {

System.err.println ("Usage:" +

"Java format/usingsystemout <format string>");

System.exit (0);

}

String format = args[0];

System.out.format ("Pi is approximately" + format +

", and E is approximately" + format, Math.PI, MATH.E);

}

}

Console call

Java format/usingsystemout%.2f%n

Output

Pi is approximately 3.14

, and E is about 2.72

The format of time is represented by the letter T, which usually follows the T with a special character to show a part of the time:

Tr hour and minute,

TA the day of the week

TB the name of the month

Te the number of the day of the month

TY the Year

eg.

Package format;

Import Java.util.Calendar;

public class Formattingdates {

public static void Main (string[] args) {

System.out.printf ("Right now it's%tr on" +

"%<ta,%<TB%<te,%<ty.%n",

Calendar.getinstance ());

}

}

Note: "<" indicates that the parameter used is the previous formatted parameter

Output

Right now it's 01:55:19 PM on Wednesday, September 22, 2004.