How to declare anonymous arraylist in java?

Question

I want to declare anonymous arraylist in java so that on the nature of constructor list can be initialize with any type of object. For example:

    ArrayList<Anonymous> list;

    public AdapterChatWindow(Activity act, ArrayList<CommentData> list, String extras) {        
        this.act = act;     
        this.list = list;
    }

    public AdapterChatWindow(Activity act, ArrayList<ChatHistory> list) {       
        this.act = act; 
        this.list = list;
    }

Is this possible? Any alternate Solution? Is this possible with list type data structure?

I have no idea what you mean by declaring anonymous arraylist. Are you asking about parameters on the constructor? You can use `List>` or `Object...`, but you may have to cast the elements. Have a look on generics - this may give you want you are looking for and also has compile-time type safety. — Jaroslaw Pawlak, Mar 12 '15 at 10:41

score 2 · Answer 1 · answered Mar 12 '15 at 10:41

2

You can use a generic type:

public class AdapterChatWindow<T>
{
    ArrayList<T> list;

    public AdapterChatWindow(Activity act, ArrayList<T> list, String extras)
// ....

Then use it like this:

AdapterChatWindow<Foo> acw = new AdapterChatWindow<Foo>(...);

answered Mar 12 '15 at 10:41

Eng.Fouad

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What's the difference between ArrayList> list; and ArrayList list; ? – Mark Henry Mar 12 '15 at 10:43
[Generics tutorial from Oracle](http://docs.oracle.com/javase/tutorial/java/generics/) – Jaroslaw Pawlak Mar 12 '15 at 10:44

score 1 · Answer 2 · answered Mar 12 '15 at 10:51

1

You can go for generic for example..

{List<? extends "your super class"> list;}

now you can initialize your list with any of the subclass of "your super class"

answered Mar 12 '15 at 10:51

Mitul Sanghani

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score 0 · Answer 3 · answered Mar 12 '15 at 10:40

0

You could just use ArrayList<Object> list but you'll have to carefully cast your array items when you want to do anything with them.

answered Mar 12 '15 at 10:40

ci_

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If you are going for `ArrayList – ortis Mar 12 '15 at 10:41
I think i have found a better answer myself by declaring arraylist like this ArrayList> list; in java. Thanks but for your help – Mark Henry Mar 12 '15 at 10:42

How to declare anonymous arraylist in java?

3 Answers3