扩展其他接口但也包含相同方法的接口

Question

只要查看 Java Collections，我就会看到 List 接口，它扩展了 Collection 接口，也包含 Collection 接口中完全相同的方法签名 - 但并非所有这些都只是一个子集。我的问题是为什么？由于它扩展了它，我们知道它默认会继承它们。为什么是子集？

扩展队列的双端队列也可以看到同样的情况，包含队列的所有方法签名。这难道不会让我们更难了解该界面的独特之处吗？

这是上述内容的一个简单示例：

public interface A {
   void someMethod();
}

public interface B extends A {
   void someMethod(); // why make this explicit?
   void anotherMethod();
}

Answer 1

一般的

一般来说，没有理由再次写出您已经从其他接口获得的方法。不要那样做。

Java文档

但是，在这种情况下Deque，它将覆盖 Javadoc，提供特定于Deque而不是一般性的更多详细信息Queue。

添加(E)

比较一下源码，例子add：

队列：

/**
 * Inserts the specified element into this queue if it is possible to do so
 * immediately without violating capacity restrictions, returning
 * {@code true} upon success and throwing an {@code IllegalStateException}
 * if no space is currently available.
 *
 * @param e the element to add
 * @return {@code true} (as specified by {@link Collection#add})
 * @throws IllegalStateException if the element cannot be added at this
 *         time due to capacity restrictions
 * @throws ClassCastException if the class of the specified element
 *         prevents it from being added to this queue
 * @throws NullPointerException if the specified element is null and
 *         this queue does not permit null elements
 * @throws IllegalArgumentException if some property of this element
 *         prevents it from being added to this queue
 */
boolean add(E e);

双端队列：

/**
 * Inserts the specified element into the queue represented by this deque
 * (in other words, at the tail of this deque) if it is possible to do so
 * immediately without violating capacity restrictions, returning
 * {@code true} upon success and throwing an
 * {@code IllegalStateException} if no space is currently available.
 * When using a capacity-restricted deque, it is generally preferable to
 * use {@link #offer(Object) offer}.
 *
 * <p>This method is equivalent to {@link #addLast}.
 *
 * @param e the element to add
 * @return {@code true} (as specified by {@link Collection#add})
 * @throws IllegalStateException if the element cannot be added at this
 *         time due to capacity restrictions
 * @throws ClassCastException if the class of the specified element
 *         prevents it from being added to this deque
 * @throws NullPointerException if the specified element is null and this
 *         deque does not permit null elements
 * @throws IllegalArgumentException if some property of the specified
 *         element prevents it from being added to this deque
 */
boolean add(E e);

差异：

_{（由 P4Merge 创建的差异）}

因此，当您使用Dequesadd方法时，您将看到另一个 Javadoc，而不是仅使用add另一个Queue.