BigDecimal 运算与比较

如题

BigDecimal 运算

/* 
 * 构造方法: 
 *      public BigDecimal(String val): 
 *  
 * 金融相关的东西(例:银行钱的小数,商品价格小数,实验小数) 
 *  
 * 成员方法: 
 *      public BigDecimal add(BigDecimal augend):加 
 *      public BigDecimal subtract(BigDecimal subtrahend):减 
 *      public BigDecimal multiply(BigDecimal multiplicand):乘 
 *      public BigDecimal divide(BigDecimal divisor):除 
 *      public BigDecimal divide(BigDecimal divisor,int scale,int roundingMode):商,几位小数,如何舍取。 
 *       
 */  
public class BigDecimalDemo {  
    public static void main(String[] args) {  
        System.out.println(0.09 + 0.01);  
        System.out.println(1.0 - 0.32);  
        System.out.println(1.015 * 100);  
        System.out.println(1.301 / 100);  
  
        // public BigDecimal add(BigDecimal augend):加  
        BigDecimal bd1 = new BigDecimal("0.09");  
        BigDecimal bd2 = new BigDecimal("0.01");  
        System.out.println("add:" + bd1.add(bd2));  
        System.out.println("----------------------");  
        // public BigDecimal subtract(BigDecimal subtrahend):减  
        BigDecimal bd3 = new BigDecimal("1.0");  
        BigDecimal bd4 = new BigDecimal("0.32");  
        System.out.println("subtract:" + bd3.subtract(bd4));  
        System.out.println("----------------------");  
        // public BigDecimal multiply(BigDecimal multiplicand):乘  
        BigDecimal bd5 = new BigDecimal("1.015");  
        BigDecimal bd6 = new BigDecimal("100");  
        System.out.println("multiply:" + bd5.multiply(bd6));  
        System.out.println("----------------------");  
        // public BigDecimal divide(BigDecimal divisor):除  
        BigDecimal bd7 = new BigDecimal("1.301");  
        BigDecimal bd8 = new BigDecimal("100");  
        System.out.println("divide:" + bd7.divide(bd8));  
        System.out.println("divide:" + bd7.divide(bd8,3,BigDecimal.ROUND_HALF_UP));  
        System.out.println("divide:" + bd7.divide(bd8,9,BigDecimal.ROUND_HALF_UP));  
    }  
}

比较

import org.apache.commons.lang3.math.NumberUtils;
import java.math.BigDecimal;

/**
 * 带小数的数字类型数据比较
 *
 * @author AndyChen
 * @since 2017-1-18
 */
public class HaveDecimalsNumberCompareTool {
    static double deviation = 10E-10;

    /**
     * 在给定精度范围内比较2个double类型值是否相等
     */
    public static boolean equals(double a, double b) {
        if (Double.isNaN(a) || Double.isNaN(b) || Double.isInfinite(a) || Double.isInfinite(b)) {
            return false;
        }

        return a == b || Math.abs(a - b) < deviation;
    }

    /**
     * 等于
     * BigDecimal.compareTo
     * -1 小于
     * 0 等于
     * 1 大于
     */
    public static boolean equals(String a, String b) {
        return getBigDecimalCompareResult(a, b) == 0;
    }

    /**
     * 介于
     *
     * @param a
     * @param b
     * @return a是否介于b与c
     */
    public static boolean between(String a, String b, String c) {
        int resultGreaterThanOrEqualBefore = getBigDecimalCompareResult(a, b);
        int lessGreaterThanOrEqualAfter = getBigDecimalCompareResult(a, c);

        return (resultGreaterThanOrEqualBefore == 0 || resultGreaterThanOrEqualBefore == 1)
                && (lessGreaterThanOrEqualAfter == 0 || lessGreaterThanOrEqualAfter == -1);
    }

    /**
     * 大于
     *
     * @param a
     * @param b
     * @return
     */
    public static boolean greaterThan(String a, String b) {
        return getBigDecimalCompareResult(a, b) == 1;
    }

    /**
     * 小于
     *
     * @param a
     * @param b
     * @return
     */
    public static boolean lessThan(String a, String b) {
        return getBigDecimalCompareResult(a, b) == -1;
    }

    /**
     * 大于等于
     *
     * @param a
     * @param b
     * @return
     */
    public static boolean greaterThanOrEqual(String a, String b) {
        return getBigDecimalCompareResult(a, b) >= 0;
    }

    /**
     * 小于等于
     *
     * @param a
     * @param b
     * @return
     */
    public static boolean lessThanOrEqual(String a, String b) {
        int result = getBigDecimalCompareResult(a, b);
        return (result == 0 || result == -1);
    }

    /**
     * 得到两个浮点数的比较结果
     *
     * @param a
     * @param b
     * @return -2: 至少有一个是非数值，0: 相等 -1: 小于 1: 大于
     */
    private static int getBigDecimalCompareResult(String a, String b) {
        BigDecimal x = NumberUtils.createBigDecimal(a);
        BigDecimal y = NumberUtils.createBigDecimal(b);

        if (x == null || y == null) {
            return -2;
        }

        return x.compareTo(y);
    }
}