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GridView Using Custom ArrayAdapter in Android with Example

Last Updated : 12 Aug, 2024
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This article will be building an application to demonstrate the use of CustomArrayAdapters in GridView. GridViews are view containers that display views in two-dimensional (rows and columns) they are used in my android applications one simple example would be the gallery app. The adapter connects the UI elements with the data source, It helps populate data with us taking care of it. e.g when the user is scrolling through a gallery app the GridView is automatically populated without specifying anything.

There are different Adapters to name a few:

This article will be covering the Custom ArrayAdapter.

Why use a Custom ArrayAdapter? 

Android already provides the implementation for an ArrayAdapter, which can be used with just a single line demonstrated below. They are used when Whenever we have a list of single items we can use ArrayAdapter. For instance, a list of phone contacts, countries, or names. Below is the syntax of the ArrayAdapter used for displaying text data.

Syntax:

ArrayAdapter(Context context, int resource, int textViewResourceId, T[] objects)

Parameters:

  • Context: is the application context being used 
  • resource: The second parameter is the resource id used to set the layout(xml file). 
  • textViewResourceId: Id of the TextView element where the data will be displayed 
  • objects: are the data elements stored in an array.

The problem with or limitation of this method is we cannot use complex layouts eg. Imagine we were building an app like Netflix or prime where each element is made up of many elements eg an ImageView, TextView, etc. Such complex views are not possible with the simple implementation of the ArrayAdapter for this we need to create our custom Adapter by extending the ArrayAdapter class. The following code shows the structure of the Custom ArrayAdapter.

Java 
import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import java.util.List;

public class CustomAdapter extends ArrayAdapter {
    public CustomAdapter(Context context, int resource,
                         List objects)
    {
        super(context, resource, objects);
    }

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

    @Override
    public View getView(int position, View convertView,
                        ViewGroup parent)
    {
        return super.getView(position, convertView, parent);
    }
}
Kotlin 
import android.content.Context
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter

class CustomAdapter(context: Context?, resource: Int, objects: List<*>?) : ArrayAdapter<Any?>(context!!, resource, objects!!) {
    
    override fun getCount(): Int {
        return super.getCount()
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        return super.getView(position, convertView, parent)
    }
}

The two important methods used are:

  1. getCount(): returns the number of data elements present in the List.
  2. getView(): this is the important method where will be initializing and returning the custom view.

Example

A sample GIF is given below to get an idea about what we are going to do in this article. We are going to implement this project using both Java and Kotlin Programming Language for Android. 

Step by Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. The code for that has been given in both Java and Kotlin Programming Language for Android.

Step 2: Working with the XML Files

Next, go to the activity_main.xml file, which represents the UI of the project. Below is the code for the activity_main.xml file. Comments are added inside the code to understand the code in more detail.

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

    <GridView
        android:id="@+id/grid_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:horizontalSpacing="10dp"
        android:numColumns="auto_fit"
        android:verticalSpacing="10dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Creating a new layout XML file 

Creating a new file named custom_view.xml in the same folder as the activity_main.xml file. This Custom View will host an ImageView and a TextView.

XML 
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        tools:srcCompat="@tools:sample/avatars" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textAlignment="center" />
</LinearLayout>

Step 3: Working with the Java/Kotlin Files

Now to hold the info of our custom view we need to create a getter setter class. We can do things without this just using two arrays one for images and the other for text but what if we want to modify your view to add a Button? Then will again need a third array. Hence a class that holds the custom view is a more flexible option. Create the class In the same folder as the MainActivity create a new class called items. Below is the code for the items file.

Java 
public class items {

    private int image_id;
    private String text;

    public int getImage_id() {
        return image_id;
    }

    public void setImage_id(int image_id) {
        this.image_id = image_id;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    items(int img, String text) {
        image_id = img;
        this.text = text;
    }
}
Kotlin 
class items internal constructor(private var image_id: Int, private var text: String) {
    fun getImage_id(): Int {
        return image_id
    }

    fun setImage_id(image_id: Int) {
        this.image_id = image_id
    }

    fun getText(): String {
        return text
    }

    fun setText(text: String) {
        this.text = text
    }

    fun items(img: Int, text: String) {
        image_id = img
        this.text = text
    }
}

Note: For an image, we store the id of the image and not the image.

Step 4: Implementing the CustomAdapter class

Create a new class classed as CustomAdapter in the same folder as items. The main method of the Adapter is the getView(). 

Java 
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

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

    View v = convertView;

    if (v == null) {
        // getting reference to the main layout and initializing
        LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = inflater.inflate(custom_layout_id, null);
    }

    // initializing the imageview and textview and setting data
    ImageView imageView = v.findViewById(R.id.imageView);
    TextView textView = v.findViewById(R.id.textView);

    // get the item using the  position param
    items item = items_list.get(position);

    imageView.setImageResource(item.getImage_id());
    textView.setText(item.getText());
    return v;
}
Kotlin 
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView

fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        
    var v = convertView
        
    if (v == null) {
        // getting reference to the main layout and initializing
        val inflater = getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        v = inflater.inflate(custom_layout_id, null)
    }

    // initializing the imageview and textview and setting data
    val imageView = v!!.findViewById<ImageView>(R.id.imageView)
    val textView = v.findViewById<TextView>(R.id.textView)

    // get the item using the  position param
    val item: items = items_list.get(position)
    imageView.setImageResource(item.getImage_id())
    textView.setText(item.getText())
    return v
}

public View inflate (int resource,ViewGroup root)

Inflate a new view hierarchy from the specified xml resource. Throws InflateException if there is an error.

resource  int: ID for an XML layout resource to load (e.g., R.layout.main_page)

root  ViewGroup: Optional view to be the parent of the generated hierarchy. This value may be null.

This method first parses out the custom_view.xml file using the inflate() method. This method is quite computationally expensive and should be used only when needed eg. when the adapter has to populate new items when the user reaches the end of the screen. After getting the reference of the view we then initialize the image view and text view from the custom_view.xml file set the data and return the view. Below is the complete code for the CustomAdapter file. Comments are added inside the code to understand the code in more detail.

Java 
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

public class CustomAdapter extends ArrayAdapter<items> {

    List<items> items_list;
    int custom_layout_id;

    public CustomAdapter(@NonNull Context context, int resource, @NonNull List<items> objects) {
        super(context, resource, objects);
        items_list = objects;
        custom_layout_id = resource;
    }

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

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        View v = convertView;
        if (v == null) {
            // getting reference to the main layout and initializing
            LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = inflater.inflate(custom_layout_id, null);
        }

        // initializing the imageview and textview and setting data
        ImageView imageView = v.findViewById(R.id.imageView);
        TextView textView = v.findViewById(R.id.textView);

        // get the item using the  position param
        items item = items_list.get(position);

        imageView.setImageResource(item.getImage_id());
        textView.setText(item.getText());
        return v;
    }
}
Kotlin 
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import android.widget.ImageView
import android.widget.TextView

class CustomAdapter(context: Context, resource: Int, objects: List<items>) : ArrayAdapter<items?>(context, resource, objects) {

    init {
        items_list = objects
        custom_layout_id = resource
    }
    
    private var items_list: List<items>
    private var custom_layout_id: Int
    
    override fun getCount(): Int {
        return items_list.size
    }

    fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        var v = convertView
        if (v == null) {
            // getting reference to the main layout and initializing
            val inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
            v = inflater.inflate(custom_layout_id, null)
        }

        // initializing the imageview and textview and setting data
        val imageView = v!!.findViewById<ImageView>(R.id.imageView)
        val textView = v.findViewById<TextView>(R.id.textView)

        // get the item using the  position param
        val item: items = items_list[position]
        imageView.setImageResource(item.getImage_id())
        textView.setText(item.getText())
        return v
    }
}

Step 5: Working with the MainActivity File

Go to the MainActivity File and refer to the following code. Below is the code for the MainActivity File. Comments are added inside the code to understand the code in more detail. For the images, here we have used android studio icons. The images are present in the res/drawable folder. Should look like this 

Java 
import android.os.Bundle;
import android.widget.GridView;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

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

        List<items> itemsList = new ArrayList<>();
        itemsList.add(new items(R.drawable.android_1, "image_1"));
        itemsList.add(new items(R.drawable.android_2, "image_2"));
        itemsList.add(new items(R.drawable.android_3, "image_3"));
        itemsList.add(new items(R.drawable.android_4, "image_4"));
        itemsList.add(new items(R.drawable.android_5, "image_5"));
        itemsList.add(new items(R.drawable.android_1, "image_6"));
        itemsList.add(new items(R.drawable.android_2, "image_7"));
        itemsList.add(new items(R.drawable.android_3, "image_8"));
        itemsList.add(new items(R.drawable.android_4, "image_9"));
        itemsList.add(new items(R.drawable.android_5, "image_10"));

        GridView gridView = findViewById(R.id.grid_view);
        CustomAdapter customAdapter = new CustomAdapter(this, R.layout.custom_view, itemsList);
        gridView.setAdapter(customAdapter);
    }
}
Kotlin 
import android.os.Bundle
import android.widget.GridView
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        val itemsList: List<items> = ArrayList<Any>()
        itemsList.add(items(R.drawable.android_1, "image_1"))
        itemsList.add(items(R.drawable.android_2, "image_2"))
        itemsList.add(items(R.drawable.android_3, "image_3"))
        itemsList.add(items(R.drawable.android_4, "image_4"))
        itemsList.add(items(R.drawable.android_5, "image_5"))
        itemsList.add(items(R.drawable.android_1, "image_6"))
        itemsList.add(items(R.drawable.android_2, "image_7"))
        itemsList.add(items(R.drawable.android_3, "image_8"))
        itemsList.add(items(R.drawable.android_4, "image_9"))
        itemsList.add(items(R.drawable.android_5, "image_10"))
        
        val gridView = findViewById<GridView>(R.id.grid_view)
        val customAdapter = CustomAdapter(this, R.layout.custom_view, itemsList)
        gridView.adapter = customAdapter
    }
}

Final Project Structure

Output:



Next Article
GridView Using BaseAdapter in Android with Example

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