package io.itjun.basic.math;

import java.math.BigDecimal;

import java.math.RoundingMode;

/**

* 对双精度浮点数四舍五入计算

*/

public class MathTool {

private static final RoundingMode mode = RoundingMode.HALF_EVEN;// 银行家舍入模式

private static final int scale = 2;// 默认保留的小数位数

private MathTool() {

}

public static double add(double v1, double v2) {

BigDecimal d1 = new BigDecimal(Double.toString(v1));

BigDecimal d2 = new BigDecimal(Double.toString(v2));

BigDecimal result = d1.add(d2);

return result.setScale(scale, mode).doubleValue();

}

public static double subtract(double v1, double v2) {

BigDecimal d1 = new BigDecimal(Double.toString(v1));

BigDecimal d2 = new BigDecimal(Double.toString(v2));

BigDecimal result = d1.subtract(d2);

return result.setScale(scale, mode).doubleValue();

}

public static double multiply(double v1, double v2) {

BigDecimal d1 = new BigDecimal(Double.toString(v1));

BigDecimal d2 = new BigDecimal(Double.toString(v2));

BigDecimal result = d1.multiply(d2);

return result.setScale(scale, mode).doubleValue();

}

public static double divide(double v1, double v2) {

BigDecimal d1 = new BigDecimal(Double.toString(v1));

BigDecimal d2 = new BigDecimal(Double.toString(v2));

BigDecimal result = d1.divide(d2, scale, mode);

return result.doubleValue();

}

public static void main(String[] args) {

// System.out.println(0.1 + 0.2);

// System.out.println(MathTool.add(0.1, 0.2));

// System.out.println(MathTool.subtract(37121, 0.475));

System.out.println(37121 * 0.475);

System.out.println(MathTool.multiply(37121, 0.475));

//

// System.out.println(6879 * 0.475);

// System.out.println(MathTool.multiply(6879, 0.475));

// System.out.println(MathTool.divide(1, 3));

}

}