Displaying Items From Json File In A RecyclerView-Android studio

JSON is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects consisting of attribute–value pairs and arrays.Source

1.Create a new android studio project

2.Create a raw directory in Res folder

3.Create a json file named cars.json and paste the following data:

[{
  "make": "Noah",
  "model": "Toyota"
},{
  "make": "Rumion",
  "model": "Toyota"
},{
  "make": "Q6",
  "model": "Audi"
},{
  "make": "Corrola cross",
  "model": "Toyota"
},{
  "make": "Axela",
  "model": "Mazda"
},{
  "make": "Atenza",
  "model": "Mazda"
},{
  "make": "Wingroad",
  "model": "Nissan"
},{
  "make": "Spade",
  "model": "Nissan"
},{
  "make": "Levante",
  "model": "Maserati"
},{
  "make": "D-Max",
  "model": "Isuzu"
},{
  "make": "X-Trail",
  "model": "Nissan"
},{
  "make": "GTR",
  "model": "Nissan"
}, {
  "make": "Legacy",
  "model": "Subaru"
}]

We will use CardView and RecyclerView in our code so add the dependancy in app-level build.gradle (Module:app)

    implementation 'androidx.recyclerview:recyclerview:1.2.1'
    implementation 'com.android.support:cardview-v7:29.0.0'

4.Create a list_item.xml in Layout for RecyclerView and paste in the following code:

Add RecyclerView in activity_main.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">


        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/my_recycler_view"
            android:scrollbars="vertical"
            tools:listitem="@layout/list_item"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>


</androidx.constraintlayout.widget.ConstraintLayout>

Create a java file called cars.java to act as a model

public class cars {
    private String model;

    public String getModel() {
        return model;
    }

    public void setModel(String model) {
        this.model = model;
    }

    public String getMake() {
        return make;
    }

    public void setMake(String make) {
        this.make = make;
    }

    private String make;
    
}

Create another java file RecyclerAdapter.java for displaying items.

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private static final int TYPE = 1;
    private final Context context;
    private final List<Object> listRecyclerItem;

    public RecyclerAdapter(Context context, List<Object> listRecyclerItem) {
        this.context = context;
        this.listRecyclerItem = listRecyclerItem;
    }

    public class ItemViewHolder extends RecyclerView.ViewHolder {

        private TextView tvModel;
        private TextView tvMake;

        public ItemViewHolder(@NonNull View itemView) {
            super(itemView);
            tvModel = (TextView) itemView.findViewById(R.id.tvModel);
            tvMake = (TextView) itemView.findViewById(R.id.tvMake);
        }
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        switch (i) {
            case TYPE:

            default:

                View layoutView = LayoutInflater.from(viewGroup.getContext()).inflate(
                        R.layout.list_item, viewGroup, false);

                return new ItemViewHolder((layoutView));
        }

    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder viewHolder, int i) {

        int viewType = getItemViewType(i);

        switch (viewType) {
            case TYPE:
            default:

                ItemViewHolder itemViewHolder = (ItemViewHolder) viewHolder;
                cars Cars = (cars) listRecyclerItem.get(i);

                itemViewHolder.tvMake.setText(Cars.getMake());
                itemViewHolder.tvModel.setText(Cars.getModel());
                
        }

    }

    @Override
    public int getItemCount() {
        return listRecyclerItem.size();
    }
    
}

Add the following activity in your MainActivity.java

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private List<Object> viewItems = new ArrayList<>();

    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager layoutManager;

    private static final String TAG = "MainActivity";

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

        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);


        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        layoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(layoutManager);

        // specify an adapter (see also next example)
        mAdapter = new RecyclerAdapter(this, viewItems);
        mRecyclerView.setAdapter(mAdapter);

        addItemsFromJSON();

    }

    private void addItemsFromJSON() {
        try {

            String jsonDataString = readJSONDataFromFile();
            JSONArray jsonArray = new JSONArray(jsonDataString);

            for (int i=0; i<jsonArray.length(); ++i) {

                JSONObject itemObj = jsonArray.getJSONObject(i);

                String model = itemObj.getString("model");
                String make = itemObj.getString("make");

                cars Cars = new cars(model, make);
                viewItems.add(Cars);
            }

        } catch (JSONException | IOException e) {
            Log.d(TAG, "addItemsFromJSON: ", e);
        }
    }

    private String readJSONDataFromFile() throws IOException{

        InputStream inputStream = null;
        StringBuilder builder = new StringBuilder();

        try {

            String jsonString = null;
            inputStream = getResources().openRawResource(R.raw.cars);
            BufferedReader bufferedReader = new BufferedReader(
                    new InputStreamReader(inputStream, "UTF-8"));

            while ((jsonString = bufferedReader.readLine()) != null) {
                builder.append(jsonString);
            }

        } finally {
            if (inputStream != null) {
                inputStream.close();
            }
        }
        return new String(builder);
    }

}

Run your code,it should be displaying items as shown below:

Thats all for any questions or comments please leave in the form below:

Source code at https://github.com/Ongoma/AndroidJsonRecyclerView