java取小数点后两位的四种方法

方法一

Long是长整型，怎么有小数，是double吧??
? java.text.DecimalFormat?? df=new?? java.text.DecimalFormat("#.##");??
? double?? d=3.14159;??
? System.out.println(df.format(d));

方法二

java.math.BigDecimal??
? BigDecimal?? bd?? =?? new?? BigDecimal("3.14159265");??
? bd?? =?? bd.setScale(2,BigDecimal.ROUND_HALF_UP);??

方法三

? class?? Test1{??
????? public?? static?? void?? main(String[]?? args){??
????????? double?? ret?? =?? convert(3.14159);??
???????????
????????? System.out.println(ret);??
????? }??
???????
????? static?? double?? convert(double?? value){??
????????? long?? l1?? =?? Math.round(value*100);?? //四舍五入??
????????? double?? ret?? =?? l1/100.0;?????????????? //注意：使用?? 100.0?? 而不是?? 100??
????????? return?? ret;??
????? }??
? }

方法四

double?? d?? =?? 13.4324;??
? d=((int)(d*100))/100;???