1. BigDecimal num1 = new BigDecimal2.225667);//这种写法不允许,会造成精度损失
2. BigDecimal num2 = new BigDecimal2);//这种写法是可以的
3. BigDecimal num = new BigDecimal“2.225667”);//一般都会这样写最好
4. int count = num.scale);
System.out.printlncount);//6 返回的是小数点后位数
好了,下面开始正式介绍知识点啦~~~~~~
1. ROUND_DOWN
BigDecimal b = new BigDecimal“2.225667”).setScale2, BigDecimal.ROUND_DOWN);
System.out.printlnb);//2.22 直接去掉多余的位数
2. ROUND_UP
BigDecimal c = new BigDecimal“2.224667”).setScale2, BigDecimal.ROUND_UP);
System.out.printlnc);//2.23 跟上面相反,进位处理
3. ROUND_CEILING
天花板(向上),正数进位向上,负数舍位向上
BigDecimal f = new BigDecimal“2.224667”).setScale2, BigDecimal.ROUND_CEILING);
System.out.printlnf);//2.23 如果是正数,相当于BigDecimal.ROUND_UP
BigDecimal g = new BigDecimal“-2.225667”).setScale2, BigDecimal.ROUND_CEILING);
System.out.printlng);//-2.22 如果是负数,相当于BigDecimal.ROUND_DOWN
4. ROUND_FLOOR
地板(向下),正数舍位向下,负数进位向下
BigDecimal h = new BigDecimal“2.225667”).setScale2, BigDecimal.ROUND_FLOOR);
System.out.printlnh);//2.22 如果是正数,相当于BigDecimal.ROUND_DOWN
BigDecimal i = new BigDecimal“-2.224667”).setScale2, BigDecimal.ROUND_FLOOR);
System.out.printlni);//-2.23 如果是负数,相当于BigDecimal.ROUND_HALF_UP
5. ROUND_HALF_UP
BigDecimal d = new BigDecimal“2.225”).setScale2, BigDecimal.ROUND_HALF_UP);
System.out.println“ROUND_HALF_UP”+d); //2.23 四舍五入(若舍弃部分>=.5,就进位)
6. ROUND_HALF_DOWN
BigDecimal e = new BigDecimal“2.225”).setScale2, BigDecimal.ROUND_HALF_DOWN);
System.out.println“ROUND_HALF_DOWN”+e);//2.22 四舍五入(若舍弃部分>.5,就进位)
7. ROUND_HALF_EVEN
BigDecimal j = new BigDecimal“2.225”).setScale2, BigDecimal.ROUND_HALF_EVEN);
System.out.printlnj);//2.22 如果舍弃部分左边的数字为偶数,则作 ROUND_HALF_DOWN
BigDecimal k = new BigDecimal“2.215”).setScale2, BigDecimal.ROUND_HALF_EVEN);
System.out.printlnk);//2.22 如果舍弃部分左边的数字为奇数,则作 ROUND_HALF_UP
System.out.println“************************************”);
System.out.println“4.05: “+new BigDecimal“4.05”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.05: 4.0 down
System.out.println“4.15: “+new BigDecimal“4.15”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.15: 4.2 up
System.out.println“4.25: “+new BigDecimal“4.25”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.25: 4.2 down
System.out.println“4.35: “+new BigDecimal“4.35”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.35: 4.4 up
System.out.println“4.45: “+new BigDecimal“4.45”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.45: 4.4 down
System.out.println“4.55: “+new BigDecimal“4.55”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.55: 4.6 up
System.out.println“4.65: “+new BigDecimal“4.65”).setScale1, BigDecimal.ROUND_HALF_EVEN));//4.65: 4.6 down
System.out.println“3.05: “+new BigDecimal“3.05”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.05: 3.0 down
System.out.println“3.15: “+new BigDecimal“3.15”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.15: 3.2 up
System.out.println“3.25: “+new BigDecimal“3.25”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.25: 3.2 down
System.out.println“3.35: “+new BigDecimal“3.35”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.35: 3.4 up
System.out.println“3.45: “+new BigDecimal“3.45”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.45: 3.4 down
System.out.println“3.55: “+new BigDecimal“3.55”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.55: 3.6 up
System.out.println“3.65: “+new BigDecimal“3.65”).setScale1, BigDecimal.ROUND_HALF_EVEN));//3.65: 3.6 down
8.ROUND_UNNECESSARY
BigDecimal l = new BigDecimal“2.215”).setScale3, BigDecimal.ROUND_UNNECESSARY);
System.out.printlnl);
//断言请求的操作具有精确的结果,因此不需要舍入。
转载自:https://blog.csdn.net/qq_39101581/article/details/78624617