Cannot make working ListView item delete action

Question

I'm making some listview based app with ability to delete specific row with a button in it, like on screenshot below: Screenshot

Here are my classes:

MainActivity: package com.example.patryk.notes;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    ListView listView;
    LayoutInflater layoutInflater;
    ArrayList<Item> itemList = new ArrayList<Item>();
    ItemArrayAdapter itemArrayAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        itemArrayAdapter = new ItemArrayAdapter(this, R.layout.list_item, itemList);
        listView = (ListView) findViewById(R.id.item_list);
        listView.setAdapter(itemArrayAdapter);

        layoutInflater = getLayoutInflater();
        ViewGroup footer = (ViewGroup) layoutInflater.inflate(R.layout.list_view_footer, listView, false);
        listView.addFooterView(footer);

        itemList.add(new Item("Item", 1));

    }

       public void addRow(View v) {
        itemList.add(new Item("Item", itemList.size() + 1));
           Log.d("add", "metoda add row");
           itemArrayAdapter.notifyDataSetChanged();
       }


}

ItemArrayAdapter

package com.example.patryk.notes;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by patryk on 04.01.2018.
 */

public class ItemArrayAdapter extends ArrayAdapter<Item> {

    private int listItemLayout;
    ImageButton deleteButton;

    public ItemArrayAdapter(Context context, int layoutId, ArrayList<Item> itemList) {
        super(context, layoutId, itemList);
        listItemLayout = layoutId;
    }

    @NonNull
    @Override
    public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        Item item = getItem(position);

        ViewHolder viewHolder;
        if (convertView == null) {
            viewHolder = new ViewHolder();
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(listItemLayout,parent, false);
          //  viewHolder.item = (TextView) convertView.findViewById(R.id.row_item);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        deleteButton = (ImageButton) convertView.findViewById(R.id.xButtonID);
        deleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                 **here expected to do something**
            }
        });


        return convertView;
    }


    private static class ViewHolder {
        TextView item;
    }

}

item

package com.example.patryk.notes;

/**
 * Created by patryk on 04.01.2018.
 */

public class Item {

    private String name;
    private double value;

    public Item(String name, double value) {
        this.value = value;
        this.name = name;
    }

    public double getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


}

I've tried many ideas from Stack Overflow but always there has been my clue missing. Firstly I wanted to make delete action on OnclickListener method in ItemArrayAdapter class, but the problem was to access ArrayList "itemList" located in MainActivity class, so I couldn't perform itemList.remove(position).

On the other hand I wanted to make deleteRow method in MainActivity and attach it to delete button on ItemArrayAdapter class by adding android:onClick="deleteRow" tag, but that makes exception similar to that: IllegalStateException I'd rather chose first idea, so I would like to know how to get access to this ArrayList within adapter class

cheers :)

Answer 1

Reference variable of ArrayList is send to the adapter class. So you can easily do this:

public class ItemArrayAdapter extends ArrayAdapter<Item> {

        private int listItemLayout;
        ImageButton deleteButton;
        private ArrayList<Item> itemList;

        public ItemArrayAdapter(Context context, int layoutId, ArrayList<Item> itemList) {
            super(context, layoutId, itemList);
            listItemLayout = layoutId;
            this.itemList = itemList;
        }

Then

deleteButton = (ImageButton) convertView.findViewById(R.id.xButtonID);
deleteButton.setTag(position);
deleteButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int pos = (int) v.getTag();
                    itemList.remove(pos);
                    notifyDataSetChanged();
                    notifyDataSetInvalidated();
                }
            });

Answer 2

You don't need to access the MainActivity, item list is available in the constructor

public ItemArrayAdapter(Context context, int layoutId, ArrayList<Item> itemList) {
        super(context, layoutId, itemList);
        listItemLayout = layoutId;
    }

You better assign to a variable and use it.

Like this

Private ArrayList <Item> itemList; 
public ItemArrayAdapter(Context context, int layoutId, ArrayList<Item> itemList) {
        super(context, layoutId, itemList);
        listItemLayout = layoutId;
        this.itemList = itemList
    }

After remove please call notifytheDataSetChange method to refresh the list view.