The type of the expression must be an array type but it resolved to Object？

测试底层源码发现报错The type of the expression must be an array type but it resolved to Object?(表达式的类型必须是数组类型，但它解析为对象)
还耽误了不少时间，我是真的无语了。
找了半天发现是把elementData 定义成了对象
你们也要劳逸结合不能马虎！！！！！！！
The type of the expression must be an array type but it resolved to Object？

报错的原因就是少了 ==== [ ]=====

报错 The type of the expression must be an array type but it resolved to Object？

程序猿加油！！！
The type of the expression must be an array type but it resolved to Object？