将BigDecimal转成字符串为科学计数法的踩坑记录

BigDecimal转字符串为科学计数法踩坑

场景

解决

案例演示

BigDecimal变科学计数法

BigDecimal转字符串为科学计数法踩坑 场景

在开发工程中，在金额方面都会定义bigdecimal类型，当然有时候也需要将金额转成字符串。我们可能会很自然的写成金额.toString()方法如：

costBudgetEntity.getInitTotalAmount().toString()//获取初始预算金额的字符串

当然当金额过小时，转成字符串，是没有任何问题的，但当金额数值较大时，转成的字符串时科学计数法格式，这往往不是我们想要的格式。

因此

costBudgetEntity.getInitTotalAmount().toString()//金额为12000000输出的结果为1.2E+7这种的字符串

然后根据这种字符串，无法做一些想要的业务处理

解决

查看BigDecimal的API后，得知有个toPlainString()方法，此方法的返回类型为String ，它返回此BigDecimal对象的字符串表示形式，不需要任何指数。

/**
* Returns a string representation of this {@code BigDecimal}
* without an exponent field.  For values with a positive scale,
* the number of digits to the right of the decimal point is used
* to indicate scale.  For values with a zero or negative scale,
* the resulting string is generated as if the value were
* converted to a numerically equal value with zero scale and as
* if all the trailing zeros of the zero scale value were present
* in the result.
*
* The entire string is prefixed by a minus sign character '-'
* (<tt>'&#92;u002D'</tt>) if the unscaled value is less than
* zero. No sign character is prefixed if the unscaled value is
* zero or positive.
*
* Note that if the result of this method is passed to the
* {@linkplain #BigDecimal(String) string constructor}, only the
* numerical value of this {@code BigDecimal} will necessarily be
* recovered; the representation of the new {@code BigDecimal}
* may have a different scale.  In particular, if this
* {@code BigDecimal} has a negative scale, the string resulting
* from this method will have a scale of zero when processed by
* the string constructor.
*
* (This method behaves analogously to the {@code toString}
* method in 1.4 and earlier releases.)
*
* @return a string representation of this {@code BigDecimal}
* without an exponent field.
* @since 1.5
* @see #toString()
* @see #toEngineeringString()
*/
public String toPlainString() {
    if(scale==0) {
        if(intCompact!=INFLATED) {
            return Long.toString(intCompact);
        } else {
            return intVal.toString();
        }
    }
    if(this.scale<0) { // No decimal point
        if(signum()==0) {
            return "0";
        }
        int tailingZeros = checkScaleNonZero((-(long)scale));
        StringBuilder buf;
        if(intCompact!=INFLATED) {
            buf = new StringBuilder(20+tailingZeros);
            buf.append(intCompact);
        } else {
            String str = intVal.toString();
            buf = new StringBuilder(str.length()+tailingZeros);
            buf.append(str);
        }
        for (int i = 0; i < tailingZeros; i++)
            buf.append('0');
        return buf.toString();
    }
    String str ;
    if(intCompact!=INFLATED) {
        str = Long.toString(Math.abs(intCompact));
    } else {
        str = intVal.abs().toString();
    }
    return getValueString(signum(), str, scale);
}

此时，我们在debug查看：