DecimalFormat df4 = new DecimalFormat("######.00");
df4.setRoundingMode(RoundingMode.HALF_UP);//网上都是说加这一行代码
double s = 3.155;
System.out.println(df4.format(s));//输出还是3.15
//jdk版本:1.8.291
DecimalFormat df4 = new DecimalFormat("######.00");
df4.setRoundingMode(RoundingMode.HALF_UP);//网上都是说加这一行代码
double s = 3.155;
System.out.println(df4.format(s));//输出还是3.15
//jdk版本:1.8.291