java - 扩展其他接口(interface)但也包含相同方法的接口(interface)

Question

只要查看 Java 集合，我就会看到 List 接口(interface)，它扩展了 Collection 接口(interface)，在 Collection 接口(interface)中也包含完全相同的方法签名——但并非所有方法都只是一个子集。我的问题是为什么？由于它扩展了它，我们知道它将默认继承它们。为什么是子集？

Deque 扩展了 Queue，包含了 Queue 的所有方法签名。这不会让了解该界面的独特之处变得更加困难吗？

这是上面的一个简单例子:

public interface A {
   void someMethod();
}

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

Answer 1

一般

一般来说，没有理由再次写出你已经从其他接口(interface)获得的方法。不要那样做。

Java文档

然而，在 Deque 的情况下，它将覆盖 Javadoc，提供更多特定于 Deque 而不是一般 Queue 的详细信息

添加(E)

对比源码，例子添加:

Queue :

/**
 * 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);

Deque :

/**
 * 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);

区别:

_{(由 P4Merge 创建的差异)}

因此，当您使用 Deque 的 add 方法时，您将看到另一个 Javadoc，而不是仅使用另一个 的 add 方法队列。