How to add item in Arraylist android

Question

I have Model (Not have Constructor, have setter and getter)

private int user_id;
private String firstname;
private String lastname;
private String pic;

and my code

List<MeModel> meModels = new ArrayList<>();

meModels.clear();
meModels.get(0).setFirstname("Hello");
meModels.get(0).setLastname("World");

it's not working.

How to add this, thanks!

where is `meModels.add(new MeModel(...))` and `clear` delete everything from list — Pavneet_Singh, Sep 20 '17 at 15:51
Why you are doing clear the list? How is it possible to get data from the list after clearing? — Mafujul, Sep 20 '17 at 15:56

Pavneet_Singh · Accepted Answer · 2017-09-20T15:57:45.910

5

After applying List#clear() will empty your list so you will no longer have the access to any item

List<MeModel> meModels = new ArrayList<>();

meModels.clear();
meModels.add(new MeModel(...));
// ^^^^^ add item
meModels.get(0).setFirstname("Hello"); // get item
meModels.get(0).setLastname("World");

edited Sep 20 '17 at 15:57

answered Sep 20 '17 at 15:54

Pavneet_Singh

36,884
5
53
68

i am glad that i could help , don't worry and you don't have to comment about yourself , sometime it happens, happy coding – Pavneet_Singh Sep 20 '17 at 16:04

score 2 · Answer 2 · answered Sep 20 '17 at 15:54

It must be returns IndexOutOfBoundsException. Because there is no item in the list. Why don't you create a constructor for your model? If I were you, I would create a constructor and do something like this:

Model model = new Model();
model.setBlahBlah(..);
meModels.add(model);

score 0 · Answer 3 · answered Sep 20 '17 at 15:59

As suggested by Pavneet_Singh you must first add an item and then you can accesss it. Like this

List<MeModel> meModels = new ArrayList<>();
meModels.clear();
meModels.add(new MeModel());
meModels.get(0).setFirstname("Hello");
meModels.get(0).setLastname("World");

Anyhow a more performant approach is to costruct first the object and then to add it to the ArrayList, like this:

List<MeModel> meModels = new ArrayList<>();
meModels.clear();
MeModel meMod = new MeModel()
meMod.setFirstname("Hello");
meMod.setLastname("World");
meModels.add(meMod);

This because as you can see by this way you save a call for each row, that is get(0). It may seems a stupid thing, but in a big iteration or on an old and less powerful device it could be important

score 0 · Answer 4 · answered Sep 20 '17 at 16:10

0

After clearing data how can you access that object. First add object using add() method then you can access those models

answered Sep 20 '17 at 16:10

SaurabhG

173
1
11

How to add item in Arraylist android

4 Answers4