如何在android中为arraylist添加值？

Question

我正在为我的arraylist添加一个值,但它显示错误.在添加值之前,我首先显示它.该值正在显示,但不会添加到arraylist.关于这个请帮帮我...

我的代码:

static ArrayList<String> allfirstids;

ArrayList<String> list = List.get(i);
UserBO user = new UserBO();

user.firstid = Integer.parseInt(list.get(0));
user.secondid = Integer.parseInt(list.get(1));
System.out.print("Hello this is first id");
System.out.print(list.get(0));

allfirstids.add(list.get(0));
System.out.println("first ids"+allfirstids);

提前致谢...

Answer 1

在添加之前,请初始化arraylist.

 allfirstids = new ArrayList<String>();