CODEWITHSUNDEEP
javaarraylist
oyan11
oyan11

Reputation: 373

How to iterate through arraylist and store to another arraylist?

i have an arraylist of objects (list1) it contains seat_no, an image and its id. How do i iterate through list1 and store every data to another list. provided that the seat_no. matches the index of the another list (list2) which has a fixed size of 50. Should i create another object class? pls help...

example:

List1 contains

|seat_no | id     | image            |
======================================
| 1      | 001    | R.drawable.chair |
| 2      | 002    | R.drawable.chair |
| 3      | 003    | R.drawable.chair |
| 4      | 004    | R.drawable.chair |
| 7      | 005    | R.drawable.chair |
| 10     | 006    | R.drawable.chair |

List2 should contain

|index   | id     | seat_no |
=============================
| 1      | 001    | 1       |
| 2      | 002    | 2       |
| 3      | 003    | 3       |
| 4      | 004    | 4       |
| 5      |"blank" |"blank"  |
| 6      |"blank" |"blank"  |
| 7      | 005    | 7       |
| 8      |"blank" |"blank"  |
| 9      |"blank" |"blank"  |
| 10     | 006    | 10      |

here's my code

main.java

ArrayList<HashMap<String, String>> take = new ArrayList<HashMap<String, String>>();

        try 
        {
            JSONObject jsonArray = new JSONObject(result);

            JSONArray info = jsonArray.getJSONArray("info");

            list1 = new ArrayList<ViewGridObject>();

            for (int i = 0; i < info.length(); i++) 
            {
                HashMap<String, String> map = new HashMap<String, String>();
                JSONObject e = info.getJSONObject(i);

                map.put("id", String.valueOf(i));
                map.put("sid", e.getString("id"));
                map.put("flag", Integer.toString(seat[0]));
                map.put("seat_no", e.getString("seat_no"));
                take.add(map);

                list1.add(new ViewGridObject(e.getString("id"), R.drawable.chair, e.getString("seat_no")));


            }

ViewGridObject.java

public class ViewGridObject 
{
public String stud_id, seat_no;
int chair;

public ViewGridObject(String stud_id, int chair, String seat_no)
{
    this.stud_id = stud_id;
    this.chair = chair;
    this.seat_no = seat_no;

}
}

Upvotes: 1

Views: 2570

Answers (2)

Bohemian
Bohemian

Reputation: 425033

It's easier to create a new list:

List<ViewGridObject> list2 = new ArrayList<ViewGridObject>();
int i = 0;
for (ViewGridObject o : list1) {
    for (i++; !o.seat_no.equals(i + ""); i++) {
        list2.add(new ViewGridObject(null, 0, i + ""));
    }
    list2.add(o);
}

Upvotes: 1

Subhrajyoti Majumder
Subhrajyoti Majumder

Reputation: 41200

No. Java ArrayList supports null value and it maintain insertion order. you can insert null where there is object available with index.

An ordered collection (also known as a sequence). The user of this interface has precise control over where in the list each element is inserted. The user can access elements by their integer index (position in the list), and search for elements in the list.

Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store the list. (This class is roughly equivalent to Vector, except that it is unsynchronized.)

ex : - you have this objects - ViewGridObject1,ViewGridObject2, ViewGridObject3, ViewGridObject4,ViewGridObject7;

list1.add(ViewGridObject1);
list1.add(ViewGridObject2);
list1.add(ViewGridObject3);
list1.add(ViewGridObject4);
list1.add(null);
list1.add(null);
list1.add(ViewGridObject7);

So your list will contain - obj1, obj2, obj3, obj4, null, null, obj7,...

Upvotes: 1

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