BigDecimal的equals奇葩传参，形参是Object,在方法中又判断形参是否为BigDecimal类型，这不矛盾吗，为什么不直接定义形参为BigDecimal类型呢

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于 2021-03-24 16:56:10 发布

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分类专栏： java 文章标签： java Bigdecimal equals

本文链接：https://blog.youkuaiyun.com/wzwsq/article/details/115181242

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该博客详细解析了BigDecimal类中的equals方法，它比较两个BigDecimal对象的值和尺度是否完全相等。当对象为非INFLATED状态时，通过intCompact属性快速判断；否则，通过inflated()方法进行精确比较。此方法不同于compareTo方法，不考虑数值的精度差异。

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/**
 * Compares this {@code BigDecimal} with the specified
 * {@code Object} for equality.  Unlike {@link
 * #compareTo(BigDecimal) compareTo}, this method considers two
 * {@code BigDecimal} objects equal only if they are equal in
 * value and scale (thus 2.0 is not equal to 2.00 when compared by
 * this method).
 *
 * @param  x {@code Object} to which this {@code BigDecimal} is
 *         to be compared.
 * @return {@code true} if and only if the specified {@code Object} is a
 *         {@code BigDecimal} whose value and scale are equal to this
 *         {@code BigDecimal}'s.
 * @see    #compareTo(java.math.BigDecimal)
 * @see    #hashCode
 */
@Override
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.inflated().equals(xDec.inflated());
}