关于Objects.equals()的一次比较，竟然出乎意料的返回了false

红太狼 2021-10-09 08:27 139阅读 0赞

public static void main(String[] args) {
            Long i = 1L;
            Integer i2 = 1;
            System.out.println(Objects.equals(i, i2));
        }

比较如上：

**翻阅源码发现，下图也没什么不妥啊？**

/**
         * Returns {@code true} if the arguments are equal to each other
         * and {@code false} otherwise.
         * Consequently, if both arguments are {@code null}, {@code true}
         * is returned and if exactly one argument is {@code null}, {@code
         * false} is returned.  Otherwise, equality is determined by using
         * the {@link Object#equals equals} method of the first
         * argument.
         *
         * @param a an object
         * @param b an object to be compared with {@code a} for equality
         * @return {@code true} if the arguments are equal to each other
         * and {@code false} otherwise
         * @see Object#equals(Object)
         */
        public static boolean equals(Object a, Object b) {
            return (a == b) || (a != null && a.equals(b));
        }

# **在翻一次源码：！！！！！！！！！！ if (obj instanceof Long) ** #

/**
         * Compares this object to the specified object.  The result is
         * {@code true} if and only if the argument is not
         * {@code null} and is a {@code Long} object that
         * contains the same {@code long} value as this object.
         *
         * @param   obj   the object to compare with.
         * @return  {@code true} if the objects are the same;
         *          {@code false} otherwise.
         */
        public boolean equals(Object obj) {
            if (obj instanceof Long) {
                return value == ((Long)obj).longValue();
            }
            return false;
        }

这个地方注意：equals在不同类型之间是不等的。