记录一个BigDecimal关于0值相等比较的问题

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我是靠谱客的博主积极滑板，最近开发中收集的这篇文章主要介绍记录一个BigDecimal关于0值相等比较的问题，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

BigDecimal a = new BigDecimal("0.0");
a.equals(BigDecimal.ZERO) // false
a.compareTo(BigDecimal.ZERO) == 0 // true

原因：

// BigDecimal#equals 源码
public boolean equals(Object x) {
    if (!(x instanceof BigDecimal))
        return false;
    BigDecimal xDec = (BigDecimal) x;
    if (x == this)
        return true;
    if (scale != xDec.scale)  // 此处会先比较小数位数，如果小数位数不一致直接返回false
        return false;
    long s = this.intCompact;
    long xs = xDec.intCompact;
    if (s != INFLATED) {
        if (xs == INFLATED)
            xs = compactValFor(xDec.intVal);
        return xs == s;
    } else if (xs != INFLATED)
        return xs == compactValFor(this.intVal);

    return this.inflated().equals(xDec.inflated());
}

// BigDecimal#compareTo 源码
public int compareTo(BigDecimal val) {
    // Quick path for equal scale and non-inflated case.
    if (scale == val.scale) {
        long xs = intCompact;
        long ys = val.intCompact;
        if (xs != INFLATED && ys != INFLATED)
            return xs != ys ? ((xs > ys) ? 1 : -1) : 0;
    }
    int xsign = this.signum();
    int ysign = val.signum();
    if (xsign != ysign)
        return (xsign > ysign) ? 1 : -1;
    if (xsign == 0)
        return 0;
    int cmp = compareMagnitude(val);
    return (xsign > 0) ? cmp : -cmp;
}