BigDecimal常用方法学习

最新推荐文章于 2025-06-02 15:45:12 发布

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本文深入探讨了BigDecimal类在Java中的应用，包括精确数学运算、数值比较与格式化等核心功能，并提供了具体示例。

public class bigDecimalMath {
    /**
     *  常用方法运算
     */
    @Test
    public void test1(){
        // 使用float会造成精度损失,尽量使用参数类型为String的构造函数。
        BigDecimal a = new BigDecimal(0.1);
        System.out.println("a = " + a);
        System.out.println("=========================");
        BigDecimal b = new BigDecimal("0.1");
        System.out.println("b = " + b);
        BigDecimal c = new BigDecimal("0.8");
        System.out.println("b + c = "+c.add(b));
        System.out.println("c - b = "+c.subtract(b));
        System.out.println("c * b = "+c.multiply(b));
        System.out.println("c / b = "+c.divide(b,2));
        //求余数
        System.out.println("c / b = "+c.remainder(b).setScale(2));
    }

    /**
     * BigDecimal大小比较
     */
    @Test
    public void test2(){
        BigDecimal a = new BigDecimal("0.1");
        BigDecimal b = new BigDecimal("0.8");
        if(b.compareTo(a) > 0){
            System.out.println("b的值比a大");
        }else if( b.compareTo(a) < 0){
            System.out.println("a的值比b大");
        }else {
            System.out.println("a和b一样大");
        }

    }

    /**
     * BigDecimal格式化
     */
    @Test
    public void test3(){
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        NumberFormat percent = NumberFormat.getPercentInstance();
        percent.setMaximumFractionDigits(3);
        BigDecimal loanAmount = new BigDecimal("15000.48"); //贷款金额
        BigDecimal interestRate = new BigDecimal("0.008"); //利率
        BigDecimal interest = loanAmount.multiply(interestRate); //相乘
        System.out.println("贷款金额:\t" + currency.format(loanAmount));
        System.out.println("利率:\t" + percent.format(interestRate));
        System.out.println("利息:\t" + currency.format(interest));
    }


    @Test
    public void test4(){
        System.out.println(formatToNumber(new BigDecimal("13.435")));
        System.out.println(formatToNumber(new BigDecimal(0)));
        System.out.println(formatToNumber(new BigDecimal("0.00")));
        System.out.println(formatToNumber(new BigDecimal("0.001")));
        System.out.println(formatToNumber(new BigDecimal("0.006")));
        System.out.println(formatToNumber(new BigDecimal("0.206")));
    }

    public static String formatToNumber(BigDecimal obj) {
        DecimalFormat df = new DecimalFormat("#.00");
        if(obj.compareTo(BigDecimal.ZERO)==0) {
            return "0.00";
        }else if(obj.compareTo(BigDecimal.ZERO)>0&&obj.compareTo(new BigDecimal(1))<0){
            return "0"+df.format(obj).toString();
        }else {
            return df.format(obj).toString();
        }
    }
}