в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

Admin: 1 версия

2010-05-31T15:29:11Z

1 версия

Новая страница

== Argument indexes enable you to reuse an argument without having to specify it twice ==



<source lang="java">
import java.util.Formatter;
public class MainClass {
public static void main(String args[]) {
Formatter fmt = new Formatter();
fmt.format("%d in hex is %1$x", 255);
System.out.println(fmt);
}
}</source>



<pre class=codeResult>255 in hex is ff</pre>

== Relative index enables you to reuse the argument matched by the preceding format specifier ==

Simply specify < for the argument index.



<source lang="java">
import java.util.Formatter;
public class MainClass {
public static void main(String args[]) {
Formatter fmt = new Formatter();
fmt.format("%d in hex is %<x", 255);
System.out.println(fmt);
}
}</source>



<pre class=codeResult>255 in hex is ff</pre>

== Relative indexes are especially useful when creating custom time and date formats ==

Because of relative indexing, the argument cal need only be passed once, rather than three times.



<source lang="java">
import java.util.Calendar;
import java.util.Formatter;
public class MainClass {
public static void main(String args[]) {
Formatter fmt = new Formatter();
Calendar cal = Calendar.getInstance();
fmt.format("Today is day %te of %<tB, %<tY", cal);
System.out.println(fmt);
}
}</source>



<pre class=codeResult>Today is day 1 of December, 2006</pre>

== Using an Argument Index ==

Normally, format specifiers and arguments are matched in order, from left to right.
However, by using an argument index you can explicitly control which argument
a format specifier matches.
An argument index immediately follows the % in a format specifier: n$,
where n is the index of the desired argument, beginning with 1.



<source lang="java">
import java.util.Formatter;
public class MainClass {
public static void main(String args[]) {
Formatter fmt = new Formatter();
fmt.format("%3$d %1$d %2$d", 10, 20, 30);
System.out.println(fmt);
}
}</source>



<pre class=codeResult>30 10 20</pre>

← Предыдущая	Версия 17:44, 31 мая 2010
(нет различий)

Java Tutorial/Development/Formatter Argument Index - История изменений

в 17:44, 31 мая 2010

Admin: 1 версия