CODEWITHSUNDEEP
androidandroid-listview
user3467178
user3467178

Reputation: 83

Android Custom Listview

I have some boring question. I am beginner of android. I am trying to make Custom Listview. I can not understand this code.

Why use ArrayAdapter<ItemList> and why pass value super(context, R.layout.activity_custom_adapter)?

Why use getView() and why use layout again R.layout.activity_custom_adapter?

public class CustomAdapter extends ArrayAdapter<ItemList> {

    ArrayList<ItemList> item;
    Activity context;

    public CustomAdapter(Activity context, ArrayList<ItemList> item) {
       super(context, R.layout.activity_custom_adapter, item);
       this.item=item;
       this.context=context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view=convertView;
        if(view==null){
            LayoutInflater inflate=context.getLayoutInflater();
            view=inflate.inflate(R.layout.activity_custom_adapter, parent, false);

        }

        return view;
    }

Upvotes: 0

Views: 79

Answers (1)

Bryan Herbst
Bryan Herbst

Reputation: 67189

Why use ArrayAdapter<ItemList>?

This means that your CustomAdapter is a subclass of ArrayAdapter, and that it will contain classes only of type ItemList. All ListViews need an adapter of some sort to translate plain Java classes into Views that the ListView can use as rows in the list.

If you aren't sure what subclasses are or how inheritance works, I highly recommend the What is Inheritance? page from the Java tutorials.

Why pass value super(context, R.layout.activity_custom_adapter)?

The ArrayAdapter class does a lot of work for you when it comes to creating an adapter for a ListView. This line calls the constructor for ArrayAdapter to ensure that all of that class' member variables are initialized properly. Again, I would check out the guide to inheritance that I linked to above.

Why use getView()?

getView() is a method defined in the root Adapter class. The @Override annotation means that we don't want to use the default getView() implementation provided by any super classes.

Remember that an adapter is responsible for converting plain Java objects into View instances for the list. Whenever the ListView needs to generate a View for another row in the list, it will call getView().

Why use layout again R.layout.activity_custom_adapter?

This layout is the layout for each individual row in the list. getView() will return a copy of this layout for each item in the list.

Upvotes: 1

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