BigDecimal

例子：加减乘除(+-*/)

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System.out.println(0.05 + 0.01); System.out.println(1.0 - 0.42); System.out.println(4.015 * 100); System.out.println(123.3 / 100);

 运算结果：

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0.060000000000000005 0.5800000000000001 401.49999999999994 1.2329999999999999

关于BigDecimal丢失精度的问题，声明BigDecimal对象的时候一定要使用它构造参数为String的类型的构造器。

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BigDecimal a1 = new BigDecimal(Double.toString(0.05)); BigDecimal a2 = new BigDecimal(Double.toString(0.01)); System.out.println(a1.add(a2)); BigDecimal b1 = new BigDecimal(Double.toString(1.0)); BigDecimal b2 = new BigDecimal(Double.toString(0.42)); System.out.println(b1.subtract(b2)); BigDecimal c1 = new BigDecimal(Double.toString(4.015)); BigDecimal c2 = new BigDecimal(Double.toString(100)); System.out.println(c1.multiply(c2)); BigDecimal d1 = new BigDecimal(Double.toString(123.3)); BigDecimal d2 = new BigDecimal(Double.toString(100)); System.out.println(d1.divide(d2, 2, BigDecimal.ROUND_HALF_UP));//应对除不尽的情况, 2 = 保留小数点后两位   ROUND_HALF_UP = 四舍五入

运算结果：

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0.06 0.58 401.5000 1.23