大家好,欢迎来到IT知识分享网。
1. BigDecimal num1 = new BigDecimal(2.225667);//这种写法不允许,会造成精度损失
2. BigDecimal num2 = new BigDecimal(2);//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.println(count);//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").setScale( 2, BigDecimal.ROUND_DOWN);
- System.out.println(b); //2.22 直接去掉多余的位数
2. ROUND_UP
- BigDecimal c = new BigDecimal( "2.224667").setScale( 2, BigDecimal.ROUND_UP);
- System.out.println(c); //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").setScale( 2, BigDecimal.ROUND_CEILING);
- System.out.println(f); //2.23 如果是正数,相当于BigDecimal.ROUND_UP
-
- BigDecimal g = new BigDecimal( "-2.225667").setScale( 2, BigDecimal.ROUND_CEILING);
- System.out.println(g); //-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").setScale( 2, BigDecimal.ROUND_FLOOR);
- System.out.println(h); //2.22 如果是正数,相当于BigDecimal.ROUND_DOWN
-
- BigDecimal i = new BigDecimal( "-2.224667").setScale( 2, BigDecimal.ROUND_FLOOR);
- System.out.println(i); //-2.23 如果是负数,相当于BigDecimal.ROUND_HALF_UP
5. ROUND_HALF_UP
- BigDecimal d = new BigDecimal( "2.225").setScale( 2, 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").setScale( 2, 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").setScale(
2, BigDecimal.ROUND_HALF_EVEN);
-
System.out.println(j);
//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").setScale(
2, BigDecimal.ROUND_HALF_EVEN);
-
System.out.println(k);
//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").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.05: 4.0 down
-
System.out.println(
"4.15: "+
new BigDecimal(
"4.15").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.15: 4.2 up
-
System.out.println(
"4.25: "+
new BigDecimal(
"4.25").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.25: 4.2 down
-
System.out.println(
"4.35: "+
new BigDecimal(
"4.35").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.35: 4.4 up
-
System.out.println(
"4.45: "+
new BigDecimal(
"4.45").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.45: 4.4 down
-
System.out.println(
"4.55: "+
new BigDecimal(
"4.55").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.55: 4.6 up
-
System.out.println(
"4.65: "+
new BigDecimal(
"4.65").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//4.65: 4.6 down
-
-
System.out.println(
"3.05: "+
new BigDecimal(
"3.05").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.05: 3.0 down
-
System.out.println(
"3.15: "+
new BigDecimal(
"3.15").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.15: 3.2 up
-
System.out.println(
"3.25: "+
new BigDecimal(
"3.25").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.25: 3.2 down
-
System.out.println(
"3.35: "+
new BigDecimal(
"3.35").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.35: 3.4 up
-
System.out.println(
"3.45: "+
new BigDecimal(
"3.45").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.45: 3.4 down
-
System.out.println(
"3.55: "+
new BigDecimal(
"3.55").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.55: 3.6 up
-
System.out.println(
"3.65: "+
new BigDecimal(
"3.65").setScale(
1, BigDecimal.ROUND_HALF_EVEN));
//3.65: 3.6 down
8.ROUND_UNNECESSARY
- BigDecimal l = new BigDecimal( "2.215").setScale( 3, BigDecimal.ROUND_UNNECESSARY);
- System.out.println(l);
- //断言请求的操作具有精确的结果,因此不需要舍入。
- //如果对获得精确结果的操作指定此舍入模式,则抛出ArithmeticException。
原文地址:https://blog.csdn.net/qq_39101581/article/details/78624617
免责声明:本站所有文章内容,图片,视频等均是来源于用户投稿和互联网及文摘转载整编而成,不代表本站观点,不承担相关法律责任。其著作权各归其原作者或其出版社所有。如发现本站有涉嫌抄袭侵权/违法违规的内容,侵犯到您的权益,请在线联系站长,一经查实,本站将立刻删除。 本文来自网络,若有侵权,请联系删除,如若转载,请注明出处:https://yundeesoft.com/32046.html