Java ArrayList 帮助!

Question

我正在学习一点java，我在谷歌图书上的一本java教科书中发现了这个问题，我已经研究了一段时间了，出于某种原因，这些看起来应该很简单。有人感到无聊并想向我展示这在 Java 代码中应该是什么样子吗？

(Using ArrayList) Write a program that creates an ArrayList, adds a Loan
object, a Date object, a string, a JFrame object, and a Circle object to the list,
and uses a loop to display all the elements in the list by invoking the object’s
toString() method.

Answer 1

此代码假设相关的各种对象具有无参数构造函数。否则只需适本地粘贴参数即可:

ArrayList<Object> list = new ArrayList<Object>();
list.add(new Loan());
list.add(new Date());
list.add(new String());
list.add(new JFrame());
list.ad(new Circle());

for (Object obj : list)
{
    System.out.println(obj.toString());
}