public ArrayList(Collection<? extends E> c)方法的一个注释 c.toArray might (incorrectly) not return Object[] (see 6260652)

/**
 * Constructs a list containing the elements of the specified
 * collection, in the order they are returned by the collection's
 * iterator.
 * 使用集合类对象初始化ArrayList
 *
 * @param c the collection whose elements are to be placed into this list
 * @throws NullPointerException if the specified collection is null
 */
public ArrayList(Collection<? extends E> c) {
    elementData = c.toArray();
    size = elementData.length;
    //刚才看了一眼这个toArray方法,确实有时候返回的不是Obdect[],
    // c.toArray might (incorrectly) not return Object[] (see 6260652)
    if (elementData.getClass() != Object[].class)
        elementData = Arrays.copyOf(elementData, size, Object[].class);
}

 


以上为ArrayList的一个构造函数,在里面有一句
c.toArray might (incorrectly) not return Object[] (see 6260652)
这个注释,参见bug6260652,java的bug官网http://bugs.java.com/bugdatabase/view_bug.do?bug_id=6260652


问题就在这儿了,List<String> strList= Arrays.asList("abc");返回的结果是String[],不谢。。。

以下为测试代码

1   public static void main(String[] args) {
2         List<String> stringList= Arrays.asList("test");
3         Object[] strList=stringList.toArray();
4         System.out.println(strList.getClass());
5     }

 

结果如下:

 

posted @ 2017-04-19 16:32  akgang  阅读(2019)  评论(0编辑  收藏  举报