一、四舍五入并保留两位小数
类似于c语言printf的输出
- printf():
double x = 8.055;
System.out.printf("%.2f\n",x);
- format():
double x = 8.055;
System.out.format("%.2f\n",x);
format()方法将double型转换为String型再输出
double x = 8.055;
String s = String.format("%.2f", x);
System.out.println( s );
创建Formatter类的对象
import java.util.Formatter;
Formatter a = new Formatter(System.out);
double x = 8.055;
a.format("%.2f\n", x);
a.close();
二、不四舍五入直接保留两位小数
创建DecimalFormat类的对象
import java.text.DecimalFormat;
DecimalFormat df = new DecimalFormat(".00");
double x = 8.055;
System.out.println(df.format(x));
创建NumberFormat对象
- setMaximumFractionDigits(2)最多保留两位小数
import java.text.NumberFormat;
NumberFormat nf = NumberFormat.getNumberInstance();
nf.setMaximumFractionDigits(2);
double x = 8.055;
double y = 8.5;
System.out.println(nf.format(x));
System.out.println(nf.format(y));
- setMinimumFractionDigits(2)至少保留两位小数
import java.text.NumberFormat;
NumberFormat nf = NumberFormat.getNumberInstance();
nf.setMinimumFractionDigits(2);
double x = 8.055;
double y = 8.5;
System.out.println(nf.format(x));
System.out.println(nf.format(y));