Dive Into BigDecimal (pending)
在Java中处理大数值的精度问题, 可以考虑使用 BigDecimal或BigInteger.环境如下:
OS: Windows XP Service Pack 2
JDK: 1.5.0_10
BigDecimal bc = new BigDecimal("15323121312.052");BigDecimal bc2 = new BigDecimal("13123234.12");Assert.assertEquals("15336244546.172", bc.add(bc2).toString());Assert.assertEquals("15309998077.932", bc.subtract(bc2).toString());Assert.assertEquals("201088908427219973.61424", bc.multiply(bc2).toString());// java.lang.ArithmeticExceptionAssert.assertEquals("1167.63300661529309057240", bc.divide(bc2).toString());
运算结果的首选标度加max(addend.scale(), augend.scale())减max(minuend.scale(), subtrahend.scale())乘multiplier.scale() + multiplicand.scale()除dividend.scale() - divisor.scale()
从某种意义上说, BigDecimal可以处理任意位数的数值, 查阅Source便可知:
BigDecimal实际上内部维护一个数组
/** * The magnitude of this BigInteger, in <i>big-endian</i> order: the * zeroth element of this array is the most-significant int of the * magnitude.The magnitude must be "minimal" in that the most-significant * int (<tt>mag</tt>) must be non-zero.This is necessary to * ensure that there is exactly one representation for each BigInteger * value.Note that this implies that the BigInteger zero has a * zero-length mag array. */ int[] mag;
// 避免小数无限循环, 指定精度位数和RoundingMode bc.divide(bc2, 3, RoundingMode.HALF_UP);
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