BigDecimal 除法

BigDecimal 除法

除法

常用方法

divide(BigDecimal divisor, int scale, int roundingMode)

参数	释义
divisor	除数
scale	保留小数位
roundingMode	舍入模式

示例

BigDecimal b1 = new BigDecimal("3");
BigDecimal b2 = new BigDecimal("7");
//计算b1除以b2的值并四舍五入保留两位小数
b1 = b1.divide(b2, 2 ,BigDecimal.ROUND_HALF_UP);
System.out.println("结果:"+b1);

结果:

结果:0.43

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舍入模式

模式	释义
ROUND_UP	只要舍去的值不为0，则进1。如1.010保留一位小数为1.1，保留两位小数为1.01。
ROUND_DOWN	无论舍去的值是多少，直接舍去（截断）。
ROUND_CEILING	向正无穷方向舍入，若是正数则表现为’ROUND_UP’，若为负数则表现为’ROUND_DOWN’。
ROUND_FLOOR	向负无穷方向舍入，若是正数则表现为’ROUND_DOWN’，若为负数则表现为ROUND_UP’'。
ROUND_HALF_UP	四舍五入。
ROUND_HALF_DOWN	五舍六入。
ROUND_HALF_EVEN	若舍去位数左边值为偶数，则五舍六入。若舍去位数左边值为奇数，则四舍五入。
ROUND_UNNECESSARY	断言得数为精确的结果，若不是则抛出ArithmeticException。

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ROUND_UP

示例:

BigDecimal b1 = new BigDecimal("1.11");
BigDecimal b2 = new BigDecimal("1.10");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_UP);
b2 = b2.divide(one, 1, BigDecimal.ROUND_UP);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:1.2
b2结果:1.1

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ROUND_DOWN

示例:

BigDecimal b1 = new BigDecimal("1.11");
BigDecimal b2 = new BigDecimal("1.10");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_DOWN);
b2 = b2.divide(one, 1, BigDecimal.ROUND_DOWN);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:1.1
b2结果:1.1

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ROUND_CEILING

示例:

BigDecimal b1 = new BigDecimal("-1.11");
BigDecimal b2 = new BigDecimal("1.11");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_CEILING);
b2 = b2.divide(one, 1, BigDecimal.ROUND_CEILING);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:-1.1
b2结果:1.2

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ROUND_FLOOR

示例:

BigDecimal b1 = new BigDecimal("-1.11");
BigDecimal b2 = new BigDecimal("1.11");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_FLOOR);
b2 = b2.divide(one, 1, BigDecimal.ROUND_FLOOR);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:-1.2
b2结果:1.1

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ROUND_HALF_UP

示例:

BigDecimal b1 = new BigDecimal("1.14");
BigDecimal b2 = new BigDecimal("1.15");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_HALF_UP);
b2 = b2.divide(one, 1, BigDecimal.ROUND_HALF_UP);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:1.1
b2结果:1.2

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ROUND_HALF_DOWN

示例:

BigDecimal b1 = new BigDecimal("1.15");
BigDecimal b2 = new BigDecimal("1.16");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_HALF_DOWN);
b2 = b2.divide(one, 1, BigDecimal.ROUND_HALF_DOWN);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:1.1
b2结果:1.2

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ROUND_HALF_EVEN

示例:

BigDecimal b1 = new BigDecimal("1.15");
BigDecimal b2 = new BigDecimal("1.25");
BigDecimal one = new BigDecimal("1");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_HALF_EVEN);
b2 = b2.divide(one, 1, BigDecimal.ROUND_HALF_EVEN);

System.out.println("b1结果:"+b1);
System.out.println("b2结果:"+b2);

结果:

b1结果:1.2
b2结果:1.2

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ROUND_UNNECESSARY

结果精度确定:

BigDecimal b1 = new BigDecimal("10");
BigDecimal one = new BigDecimal("2");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_UNNECESSARY);

System.out.println("b1结果:"+b1);

结果:

b1结果:5.0

结果精度不确定:

BigDecimal b1 = new BigDecimal("3");
BigDecimal one = new BigDecimal("7");

b1 = b1.divide(one, 1 ,BigDecimal.ROUND_UNNECESSARY);

System.out.println("b1结果:"+b1);

结果:

Exception in thread "main" java.lang.ArithmeticException: Rounding necessary
at java.math.BigDecimal.commonNeedIncrement(BigDecimal.java:4148)
at java.math.BigDecimal.needIncrement(BigDecimal.java:4204)
at java.math.BigDecimal.divideAndRound(BigDecimal.java:4112)
at java.math.BigDecimal.divide(BigDecimal.java:5183)
at java.math.BigDecimal.divide(BigDecimal.java:1561)
at test.test.main(test.java:10)