Java 中的 NumberFormat 类
NumberFormat 是所有数字格式的抽象基类。这个类提供了格式化和解析数字的接口。NumberFormat 还提供了确定哪些地区(美国、印度、意大利等)有数字格式以及它们的名称的方法。NumberFormat 帮助您格式化和解析任何地区的数字。
例:假设我们有一个双数型数。但是这个双数在不同的国家有不同的表现方式。要根据不同的国家表示一个数字，我们必须借助 NumberFormat 类，如:
double d = 123456.789;
For India, it is represented like 1,23,456.789
For US, it is represented like 123,456.789
For ITALY, it is represented like 123.456,789
number format 类的一些要点:
- NumberFormat class exists in java.text package and is an abstract class.
- The number class realizes serializability and cloning.
- NumberFormat is a direct subclass of the Format class.
- Number formats are generally out of sync. It is recommended to create a separate format instance for each thread. If multiple threads access a format at the same time, it must be synchronized externally.
number format 类中存在的方法:
- public static numberformat getinstance (); : Get the NumberFormat object of the default locale.
- public static numberformat get currency instance (); : Get the numeric format object of the default locale, expressed in a specific currency.
- 菲公 number 格式 getpercentinstance:
- public static numberformat getinstance (locale l); : Get the NumberFormat object of the specified area object.
- Public static format (length l); : Convert java number to locale object.
// Java Program to illustrate NumberFormat class use
import java.util.*;
import java.text.*;
class NumberFormatDemo {
public static void main(String[] args) {
double d = 123456.789;
NumberFormat nf = NumberFormat.getInstance(Locale.ITALY);
System.out.println("ITALY representation of " + d + " : "
+ nf.format(d));
}
}
输出:
ITALY representation of 123456.789 : 123.456, 789
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