java格式化数字

Java数字的格式化

 

1、API层次结构：

java.text.Format
                java.text.DateFormat
                                java.text.SimpleDateFormat
                java.text.MessageFormat
                java.text.NumberFormat
                                java.text.ChoiceFormat
                                java.text.DecimalFormat

主要用到粗体显示的类。

 

 

2、例子

 

import java.text.NumberFormat;
import java.text.DecimalFormat;
import java.util.Locale;

/**
* Created by IntelliJ IDEA.
*
* @author leizhimin 2010-3-22 19:12:33
*/
public class TestNumFormat {

        public staticvoid main(String[] args) {

                DecimalFormat df1 = new DecimalFormat("###.00");
                System.out.println(df1.format(234234.234634));
                System.out.println(df1.format(34.234634));

                DecimalFormat df2 = new DecimalFormat("0.00E0000");
                System.out.println(df2.format(23423.34234234));

                DecimalFormat df3 = (DecimalFormat)NumberFormat.getInstance(Locale.CHINESE);
                df3.applyPattern("####.000");
                System.out.println(df3.format(23423.34234234));
                df3.applyPattern("00.0000%");
                System.out.println(df3.format(0.5552445));

                NumberFormat nf1 = NumberFormat.getInstance();
                System.out.println(nf1.format(13423423.234234));

                NumberFormat nf2 = NumberFormat.getPercentInstance();
                System.out.println(nf2.format(0.55));

        }
}

 

输出结果：

234234.23
34.23
2.34E0004
23423.342
55.5244%
13,423,423.234
55%

Process finished with exit code 0

 

如果要将带一定格式的字符串数字转化为数字类型，则值需要调用格式对象的parse()方法即可。

 

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如果想看看数字取整，可以参看：

java取整和java四舍五入方法

如果想看数字如何舍入，可参看博文：

http://lavasoft.blog.51cto.com/62575/228705