Listview custom adapter - row loses content after new item is added

Question

I am using a custom listview adapter to capture multiple objects of the same domain class Food. This class is:

public class Food {
    public String Item;
    public String Description;
    public int count;
}

My custom Adapter is:

public class FoodAdapter extends ArrayAdapter<Food> {
    private final Context context;
    private final ArrayList<Food> itemsArrayList;

    EditText item
    EditText desc
    EditText count;


    public ArrayList<Food> getItemsArrayList() {
        return itemsArrayList;
    }

    public FoodAdapter(Context context, ArrayList<Food> itemsArrayList) {

        super(context, R.layout.fr_row, itemsArrayList);
        //super(context, itemsArrayList);

        this.context = context;
        this.itemsArrayList = itemsArrayList;

    }

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

        // 1. Create inflater
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        // 2. Get rowView from inflater
        View rowView = inflater.inflate(R.layout.fr_row, parent, false);

        // 3. Get the two text view from the rowView
        item= (EditText) rowView.findViewById(R.id.f_item);
        desc= (EditText) rowView.findViewById(R.id.f_desc);
        count = (EditText) rowView.findViewById(R.id.f_count);


        return rowView;
    }

}

And my ActivityThat coordinates this listview is:

package com.example.foodie;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.telephony.TelephonyManager;
import android.view.View;
import android.widget.ListView;


public class FoodActivity extends AppCompatActivity {


    ListView lv;
    FoodAdapter adapter;
    ArrayList<Food> fList;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_frmorning);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        setContentView(R.layout.activity_frmorning);

        lv = (ListView) findViewById(R.id.list);

        fList = new ArrayList<Food>();

        adapter =new FoodAdapter(this, fList);
        lv.setAdapter(adapter);

    }

    public void addItems(View v) {

        fList.add(new Food());
        adapter.notifyDataSetChanged();
    }


}

This addItems is a button on the layout (in FoodActivity). When I tap on the add, I get the new row. But, the rows lose all content after the new row is added. They all are blank. What is causing this behaviour and how to solve? Also, how can I bind the EditText fields to the data in the ArrayList, so that when I call getItemsArrayList() I get the correct ArrayList that corresponds to the screen display?

Answer 1

When you are not using Holder so getView() method will call findViewById() as many times as you row(s) will be out of View. So if you have 1000 rows in List and 990 rows will be out of View then 990 times will be called findViewById() again.

Holder design pattern is used for View caching - Holder (arbitrary) object holds child widgets of each row and when row is out of View then findViewById() won't be called but View will be recycled and widgets will be obtained from Holder.

public class FoodAdapter extends ArrayAdapter<Food>
    {
      private final Context context;
      private final ArrayList<Food> itemsArrayList;
      public FoodAdapter(Context context, ArrayList<Food> itemsArrayList) {
        {  
        super(context, itemsArrayList);
        this.context = context;
        this.itemsArrayList = itemsArrayList;
        }
        @Override
        public int getCount() 
        {
            return itemsArrayList.size();
        }

        @Override
        public Object getItem(int position) 
        {
            return itemsArrayList.get(position);
        }

        @Override
        public long getItemId(int position) 
        {
            return position;
        }

        @Override
        public View getView(final int position, View convertView, ViewGroup parent) {
            final ViewHolder holder;
            if (convertView == null)
            {
                holder = new ViewHolder();
                LayoutInflater inflater=(LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                convertView = inflater.inflate(R.layout.fr_row, parent, false);
                holder.text = (EditText ) convertView.findViewById(R.id.edittext);

                convertView.setTag(holder);
            } else 
            {
                holder = (ViewHolder) convertView.getTag();
            }
            holder.text.setText(itemsArrayList.get(position));


            return convertView;
        }

        class ViewHolder
        {
            EditText item
            EditText desc
            EditText count;
        }

    }`enter code here`