ViewHolder Pattern with BaseAdapter in Android

Post Views: 5,615

Hello Friends, today we are going see an example of ViewHolder Pattern with BaseAdapter in Android. I am sharing this code example because few weeks ago I was working on a project and after completing code, I have analyzed my code using “Inspect Code…” feature of Android Studio which is available under Analyze menu. And I found performance issue in my code (see screenshot below). Then I googled and found this solution which I am sharing now.

without-viewholder-pattern — Unconditional layout inflation from view adapter: Should use View Holder pattern (use recycled view passed into this method as the second parameter) for smoother scrolling

Let’s Code Now

MainActivity.java

package com.zatackcoder.viewholderpatternwithbaseadapter;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class MainActivity extends AppCompatActivity {

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

        List<Item> items = new ArrayList<>();
        Random random = new Random();
        for(int i = 1; i <= 2000; i++) {
            items.add(new Item("Item " + i, random.nextInt(1000)));
        }

        ListView listView = findViewById(R.id.list_view);
        listView.setAdapter(new MyBaseAdapter(this, items));
    }
}

package com.zatackcoder.viewholderpatternwithbaseadapter;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import android.widget.ListView;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

public class MainActivity extends AppCompatActivity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

List<Item> items = new ArrayList<>();

Random random = new Random();

for(int i = 1; i <= 2000; i++) {

items.add(new Item("Item " + i, random.nextInt(1000)));

}

ListView listView = findViewById(R.id.list_view);

listView.setAdapter(new MyBaseAdapter(this, items));

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ListView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".MainActivity">

<ListView

android:id="@+id/list_view"

android:layout_width="match_parent"

android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

MyBaseAdapter.java

package com.zatackcoder.viewholderpatternwithbaseadapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

class MyBaseAdapter extends BaseAdapter {
    private final Context context;
    private final List<Item> items;

    public MyBaseAdapter(Context context, List<Item> items) {
        this.context = context;
        this.items = items;
    }

    @Override
    public int getCount() {
        return items.size();
    }

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

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if(convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);

            viewHolder = new ViewHolder();
            viewHolder.nameTV = convertView.findViewById(R.id.name);
            viewHolder.priceTV = convertView.findViewById(R.id.price);

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        /*
        convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);

        ViewHolder viewHolder = new ViewHolder();
        viewHolder.nameTV = convertView.findViewById(R.id.name);
        viewHolder.priceTV = convertView.findViewById(R.id.price);
        */
        final Item item = items.get(position);

        viewHolder.nameTV.setText(item.getName());
        viewHolder.priceTV.setText(String.valueOf(item.getPrice()));
        convertView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(context, "You Just Clicked " + item.getName(), Toast.LENGTH_LONG).show();
            }
        });
        return convertView;
    }

    static class ViewHolder {
        TextView nameTV;
        TextView priceTV;
    }
}

package com.zatackcoder.viewholderpatternwithbaseadapter;

import android.content.Context;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.TextView;

import android.widget.Toast;

import java.util.List;

class MyBaseAdapter extends BaseAdapter {

private final Context context;

private final List<Item> items;

public MyBaseAdapter(Context context, List<Item> items) {

this.context = context;

this.items = items;

}

@Override

public int getCount() {

return items.size();

}

@Override

public Object getItem(int position) {

return items.get(position);

}

@Override

public long getItemId(int position) {

return 0;

}

@Override

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

ViewHolder viewHolder;

if(convertView == null) {

convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);

viewHolder = new ViewHolder();

viewHolder.nameTV = convertView.findViewById(R.id.name);

viewHolder.priceTV = convertView.findViewById(R.id.price);

convertView.setTag(viewHolder);

} else {

viewHolder = (ViewHolder) convertView.getTag();

}

convertView = LayoutInflater.from(context).inflate(R.layout.list_item, parent, false);

ViewHolder viewHolder = new ViewHolder();

viewHolder.nameTV = convertView.findViewById(R.id.name);

viewHolder.priceTV = convertView.findViewById(R.id.price);

final Item item = items.get(position);

viewHolder.nameTV.setText(item.getName());

viewHolder.priceTV.setText(String.valueOf(item.getPrice()));

convertView.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

Toast.makeText(context, "You Just Clicked " + item.getName(), Toast.LENGTH_LONG).show();

}

});

return convertView;

}

static class ViewHolder {

TextView nameTV;

TextView priceTV;

}

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="5dp"
    android:background="#ffffff"
    android:clickable="true"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?android:attr/selectableItemBackground"
        android:orientation="vertical"
        android:padding="5dp">

        <TextView
            android:id="@+id/name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Name"
            android:textFontWeight="bold"
            android:textSize="15dp" />

        <TextView
            android:id="@+id/price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Price: 100"
            android:textSize="12dp" />

    </LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:layout_margin="5dp"

android:background="#ffffff"

android:clickable="true"

android:orientation="vertical">

<LinearLayout

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:background="?android:attr/selectableItemBackground"

android:orientation="vertical"

android:padding="5dp">

<TextView

android:id="@+id/name"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:text="Name"

android:textFontWeight="bold"

android:textSize="15dp" />

<TextView

android:id="@+id/price"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Price: 100"

android:textSize="12dp" />

</LinearLayout>

Item.java

package com.zatackcoder.viewholderpatternwithbaseadapter;

class Item {

    private String name;
    private Integer price;

    public Item(String name, Integer price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

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

    public Integer getPrice() {
        return price;
    }

    public void setPrice(Integer price) {
        this.price = price;
    }
}

package com.zatackcoder.viewholderpatternwithbaseadapter;

class Item {

private String name;

private Integer price;

public Item(String name, Integer price) {

this.name = name;

this.price = price;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public Integer getPrice() {

return price;

}

public void setPrice(Integer price) {

this.price = price;

}

Video

AndroidStudio Project Download

ViewHolderPatternWithBaseAdapter AndroidStudio Project

1 file(s) 8.13 MB

Download

References

https://www.javacodegeeks.com/2013/09/android-viewholder-pattern-example.html