/** * 提供精確的加法運算 * @param args */ public static double add(double v1, double v2) { BigDecimal b1 = new BigDecimal(Double.toString(v1)); BigDecimal b2 = new BigDecimal(Double.toString(v2)); return b1.add(b2).doubleValue(); } /** * 提供了精確的減法運算 * * @param args */ public static double sub(double v1, double v2) { BigDecimal b1 = new BigDecimal(Double.toString(v1)); BigDecimal b2 = new BigDecimal(Double.toString(v2)); return b1.subtract(b2).doubleValue(); } /** * 提供了精確的乘法運算 * @param args */ public static double mul(double v1, double v2) { BigDecimal b1 = new BigDecimal(Double.toString(v1)); BigDecimal b2 = new BigDecimal(Double.toString(v2)); return b1.multiply(b2).doubleValue(); } /** * 提供了(相對)精確的除法運算,當發生除不儘的情況時,精確到 * 小數點以後110位 * @param args */ public static double div(double v1, double v2) { return div(v1, v2, DEF_DIV_SCALE); } /** * 提供了(相對)精確的除法運算,當發生除不儘的情況時,由scale參數指定 * 精度,以後的數字四捨五入 * @param args */ public static double div(double v1, double v2, int scale) { if (scale < 0) { throw new IllegalArgumentException( "The scale must be a positive integer or zero"); } BigDecimal b1 = new BigDecimal(Double.toString(v1)); BigDecimal b2 = new BigDecimal(Double.toString(v2)); return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue(); } /** * 提供了精確的小數位四捨五入處理 * @param args */ public static double round(double v, int scale) { if (scale<0) { throw new IllegalArgumentException("The scale must be a positive integer or zero"); } BigDecimal b = new BigDecimal(Double.toString(v)); BigDecimal one = new BigDecimal("1"); return b.divide(one, scale, BigDecimal.ROUND_HALF_DOWN).doubleValue(); } public static void main(String[] args) { System.out.println(add(1.2321231, 3.7865765)); System.out.println(sub(6.4523423, 1.2321231)); System.out.println(mul(6.4523423, 3.7865765)); System.out.println(div(6.4523423, 3.7865765, 5)); System.out.println(round(3.7865765, 5)); } }