（44）：为所有导出的API元素编写文档注释

要想使一个API真正可用，就必须为其编写文档。Java提供了Javadoc工具，使得为API编写文档变得非常容易。Javadoc利用特殊格式的文档注释，根据源代码自动生成API文档。

示例：

/** * Returns the element at the specified position in this list. * * <p>This method is <i>not</i> guaranteed to run in constant * time. In some implementations it may run in time proportional * to the element position. * * @param index index of element to return; must be *        non-negative and less than the size of this list * @return the element at the specified position in this list * @throws IndexOutOfBoundsException if the index is out of range *         ({@code index < 0 || index >= this.size()}) */E get(int index);