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 static void 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:
如果想看数字如何舍入,可参看博文: