How to find the index of array in custom array list ...?

Question

I want tofind the index of the custom array list. This is my custom array list:

private ArrayList<UserData> ListItems = new ArrayList<>();

UserData list = new UserData("list", "5", R.drawable.email_black, false);

UserData list1 = new UserData("list1", "3",R.drawable.text_msg, false);

UserData list2 = new UserData("list2", "2",R.drawable.phone_call, false);

ListItems.add(list);
ListItems.add(list1);
ListItems.add(list2);

I am doing like below but not getting the index .

int m = ListItems.indexOf("list1");

UserData obj = ListItems.get(m);
String name = obj.getName();

I need list1 in name string.

You will have to pass the userData object in listItems.indexOf() not the string in order to get the index. — Glenn
– Glenn, Commented Jul 21, 2016 at 6:21
That is Custom object not custom list. You have to pass ListItems.indexOf(list1), here list1 is a UserData object(Custom Object in your case). — Saritha G
– Saritha G, Commented Jul 21, 2016 at 6:23
As mentioned by Glenn passing the userData object is the right way to go, also if it is possible you could get items based on index. — g90
– g90, Commented Jul 21, 2016 at 6:23

Saritha G · Accepted Answer · 2016-07-21 06:33:16Z

3

Iterator your array list to get your required data. Do something like below:

    for (int i = 0; i < ListItems.size(); i++) {
        String userListName = ListItems.get(i).getListName();
        if(userListName.equals("list1")){
            //Do something here
        }else{
            //Nthng to do
        }
    }

answered Jul 21, 2016 at 6:33

Saritha G

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Mureinik · Accepted Answer · 2016-07-21 06:24:41Z

1

The indexOf method is based on the argument and the item in the list being equal. Since they are not (one is a UserData instance and the other is a String), you can't use indexOf. Instead, you'll have to implement this logic yourself:

private UserData getUserDataByName(String name) {
    for (UserData item : listItems) {
        if (item.getName().equals(name)) {
            return item;
        }
    }
    // Not found, return null;
    return null;
}

answered Jul 21, 2016 at 6:24

Mureinik

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2 Comments

sunny Over a year ago

where to store return item ; UserData item = getUserDataByName("list1"); String name = item.getName(); it's wotking or'not.....?

Mureinik Over a year ago

@samir yes, that should work. If you want to be extra cautious, you should check item != null before calling item.getName() though.

Arjit · Accepted Answer · 2016-07-21 06:40:16Z

1

In such a scenario, You can use HashMap also. Use HashMap<String,UserData> where String would be "list", "list1" etc.

Ex -

map.put("list", list);

answered Jul 21, 2016 at 6:40

Arjit

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