Set源码解析

Set接口继承了Collection接口，继承了所有Collection接口的方法，下面予以分析Set源码。

package java.util;/** * 不包含有重复元素的无序集合。通过.equals()方法校验是否重复 */public interface Set<E> extends Collection<E> {    // Query Operations    /**     * Returns the number of elements in this set (its cardinality).  If this     * set contains more than <tt>Integer.MAX_VALUE</tt> elements, returns     * <tt>Integer.MAX_VALUE</tt>.     *     * @return the number of elements in this set (its cardinality)     * 返回set中元素的数量     * 如果元素数量大于2^31-1，返回的值为2^31-1     */    int size();    /**     * set集合是否为空，若为空，则返回true     *               若不为空，则返回false     */    boolean isEmpty();    /**     * set集合是否包含元素o,若包含，返回true;否则返回false     */    boolean contains(Object o);    /**     * 返回set集合的迭代器     */    Iterator<E> iterator();    /**     * 将set集合转化为数组     */    Object[] toArray();    /**     * Returns an array containing all of the elements in this set; the     * runtime type of the returned array is that of the specified array.     * If the set fits in the specified array, it is returned therein.     * Otherwise, a new array is allocated with the runtime type of the     * specified array and the size of this set.     *     * <p>If this set fits in the specified array with room to spare     * (i.e., the array has more elements than this set), the element in     * the array immediately following the end of the set is set to     * <tt>null</tt>.  (This is useful in determining the length of this     * set <i>only</i> if the caller knows that this set does not contain     * any null elements.)     *     * <p>If this set makes any guarantees as to what order its elements     * are returned by its iterator, this method must return the elements     * in the same order.     *     * <p>Like the {@link #toArray()} method, this method acts as bridge between     * array-based and collection-based APIs.  Further, this method allows     * precise control over the runtime type of the output array, and may,     * under certain circumstances, be used to save allocation costs.     *     * <p>Suppose <tt>x</tt> is a set known to contain only strings.     * The following code can be used to dump the set into a newly allocated     * array of <tt>String</tt>:     *     * <pre>     *     String[] y = x.toArray(new String[0]);</pre>     *     * Note that <tt>toArray(new Object[0])</tt> is identical in function to     * <tt>toArray()</tt>.     *     * @param a the array into which the elements of this set are to be     *        stored, if it is big enough; otherwise, a new array of the same     *        runtime type is allocated for this purpose.     * @return an array containing all the elements in this set     * @throws ArrayStoreException if the runtime type of the specified array     *         is not a supertype of the runtime type of every element in this     *         set     * @throws NullPointerException if the specified array is null     */    <T> T[] toArray(T[] a);    // Modification Operations    /**     * 向set中添加元素e     */    boolean add(E e);    /**     * 移除元素o     */    boolean remove(Object o);    // Bulk Operations    /**     * set是否包含c中所有元素     */    boolean containsAll(Collection<?> c);    /**     * 将c中所有元素添加到set中     */    boolean addAll(Collection<? extends E> c);    /**     * 保留c中所有元素     */    boolean retainAll(Collection<?> c);    /**     * 移除set中所有c的元素     */    boolean removeAll(Collection<?> c);    /**     * 移除所有set元素     */    void clear();    // Comparison and hashing    /**     * 是否为同一对象     */    boolean equals(Object o);    /**     * 获取set的hash值     */    int hashCode();}