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;
/**
*
*/
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。