BigDecimal对比大小使用compare而不使用equals

在bigdecimal的对比大小中，建议使用compare而不是使用equals。

0和0.00对比

按理说0和0.00应该是相等，但在上图中发现返回结果却是false。

0和0对比

compare

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)
            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.inflate().equals(xDec.inflate());
    }

可以发现当小数位scale不等时，自动返回了false。
compare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;
    }

signnum源码：

public int signum() {
        return (intCompact != INFLATED)?
            Long.signum(intCompact):
            intVal.signum();
    }

compare源码可见，先对小数位scale进行了对比，如果不等，又将两个数进行了转换，转成int，对比int的大小。