Recycler view android studioAttempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

Question

I am creating an app called Pricepointcrypto in which when a certain crypto currencies of your intersenst hit you budget range then you will get notfied say you wanted to buy Bitcoin 15,000 the stock market hits that you will get notfied, in this app i need to display crypto currencies and their rates and i am using coinmarket cap API for in adroid studio with java. i have already created the request and response functionalty in java and it does work on the backewnd but i have a layout issue on the rcyler view when it tries top render then when we want to setText it says its null

Here is the error i get:

java.lang.NullPointerException: Attempt to invoke virtual method 'void 
android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference

I am just stuck on this part i have tried numerous tests so if someone could help it would be really helpfull

Thanks

Here is the Code:

Main Acitivty.java

package com.example.pricepointcrypto;

import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class MainActivity extends AppCompatActivity {

private ArrayList<CurrencyModal> currencyModalArrayList;
private CurrencyRVAdapter currencyRVAdapter;
private ProgressBar loadingPB;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    EditText searchEdt = findViewById(R.id.idEdtCurrency);

    // initializing all our variables and array list.
    loadingPB = findViewById(R.id.idPBLoading);
    // creating variable for recycler view,
    // adapter, array list, progress bar
    RecyclerView currencyRV = findViewById(R.id.idRVcurrency);
    currencyModalArrayList = new ArrayList<>();

    // initializing our adapter class.
    currencyRVAdapter = new CurrencyRVAdapter(currencyModalArrayList, this);

    // setting layout manager to recycler view.
    currencyRV.setLayoutManager(new LinearLayoutManager(this));

    // setting adapter to recycler view.
    currencyRV.setAdapter(currencyRVAdapter);

    // calling get data method to get data from API.
    getData();

    // on below line we are adding text watcher for our
    // edit text to check the data entered in edittext.
    searchEdt.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

        }

        @Override
        public void afterTextChanged(Editable s) {
            // on below line calling a
            // method to filter our array list
            filter(s.toString());
        }
    });
}

private void filter(String filter) {
    // on below line we are creating a new array list
    // for storing our filtered data.
    ArrayList<CurrencyModal> filteredlist = new ArrayList<>();
    // running a for loop to search the data from our array list.
    for (CurrencyModal item : currencyModalArrayList) {
        // on below line we are getting the item which are
        // filtered and adding it to filtered list.
        if (item.getName().toLowerCase().contains(filter.toLowerCase())) {
            filteredlist.add(item);
        }
    }
    // on below line we are checking
    // weather the list is empty or not.
    if (filteredlist.isEmpty()) {
        // if list is empty we are displaying a toast message.
        Toast.makeText(this, "No currency found..", Toast.LENGTH_SHORT).show();
    } else {
        // on below line we are calling a filter
        // list method to filter our list.
        currencyRVAdapter.filterList(filteredlist);
    }
}

private void getData() {
    // creating a variable for storing our string.
    String url = "https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest";
    // creating a variable for request queue.
    RequestQueue queue = Volley.newRequestQueue(this);
    // making a json object request to fetch data from API.
    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url, null,          
response -> {
        // inside on response method extracting data
        // from response and passing it to array list
        // on below line we are making our progress
        // bar visibility to gone.
        loadingPB.setVisibility(View.GONE);
        try {
            // extracting data from json.
            JSONArray dataArray = response.getJSONArray("data");
            for (int i = 0; i < dataArray.length(); i++) {
                JSONObject dataObj = dataArray.getJSONObject(i);
                String symbol = dataObj.getString("symbol");
                String name = dataObj.getString("name");
                JSONObject quote = dataObj.getJSONObject("quote");
                JSONObject USD = quote.getJSONObject("USD");
                double price = USD.getDouble("price");

                String finalName = ""+name+" - "+symbol+"";

                // adding all data to our array list.
                currencyModalArrayList.add(new CurrencyModal(finalName, 
 R.drawable.ic_launcher_foreground, price));
            }
            // notifying adapter on data change.
            currencyRVAdapter.notifyDataSetChanged();
        } catch (JSONException e) {
            // handling json exception.
            e.printStackTrace();
            Toast.makeText(MainActivity.this, "Something went amiss. Please try again later", 
Toast.LENGTH_SHORT).show();
        }
    }, error -> {
        // displaying error response when received any error.
        Toast.makeText(MainActivity.this, "Something went amiss. Please try again later", 
Toast.LENGTH_SHORT).show();
    }) {
        @Override
        public Map<String, String> getHeaders() {
            // in this method passing headers as
            // key along with value as API keys.
            HashMap<String, String> headers = new HashMap<>();
            headers.put("X-CMC_PRO_API_KEY", "106d7841-b282-4c8c-aa0f-d53509398468");
            // at last returning headers
            return headers;
        }
    };
    // calling a method to add our
    // json object request to our queue.
    queue.add(jsonObjectRequest);
}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
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:background="@color/blac_shade_1"
tools:context=".MainActivity">

<!--edit text for searching our currency-->
<EditText
    android:id="@+id/idEdtCurrency"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="8dp"
    android:focusable="auto"
    android:hint="Search Currency"
    android:textColor="@color/white"
    android:textColorHint="@color/white" />

<!--recycler view for displaying the list of currencies-->
<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/idRVcurrency"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_below="@id/idEdtCurrency"
    tools:listitem="@layout/crypto_card_layout" />

<!--progress bar for loading indicator-->
<ProgressBar
    android:id="@+id/idPBLoading"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:visibility="gone" />

   </RelativeLayout>

CurrencyRVApdapter

package com.example.pricepointcrypto;

import android.annotation.SuppressLint;
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.recyclerview.widget.RecyclerView;

import java.text.DecimalFormat;
import java.util.ArrayList;

// on below line we are creating our adapter class
// in this class we are passing our array list
// and our View Holder class which we have created.
public class CurrencyRVAdapter extends 
RecyclerView.Adapter<CurrencyRVAdapter.CurrencyViewholder> {
private static DecimalFormat df2 = new DecimalFormat("#.##");
private ArrayList<CurrencyModal> currencyModals;
private Context context;

public CurrencyRVAdapter(ArrayList<CurrencyModal> currencyModals, Context context) {
    this.currencyModals = currencyModals;
    this.context = context;
}

// below is the method to filter our list.
public void filterList(ArrayList<CurrencyModal> filterllist) {
    // adding filtered list to our
    // array list and notifying data set changed
    currencyModals = filterllist;
    notifyDataSetChanged();
}

@NonNull
@Override
public CurrencyRVAdapter.CurrencyViewholder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    // this method is use to inflate the layout file
    // which we have created for our recycler view.
    // on below line we are inflating our layout file.
    View view = LayoutInflater.from(context).inflate(R.layout.crypto_card_layout , parent, false);
    return new CurrencyViewholder(view);
}

@SuppressLint("SetTextI18n")
@Override
public void onBindViewHolder(@NonNull CurrencyRVAdapter.CurrencyViewholder holder, int position) {
    // on below line we are setting data to our item of
    // recycler view and all its views.

    CurrencyModal modal = currencyModals.get(position);



    holder.nameTV.setText(modal.getName());
    holder.rateTV.setText("$ " + df2.format(modal.getPrice()) + " USD");
    holder.symbolTV.setImageResource(modal.getSymbol());

}

@Override
public int getItemCount() {
    // on below line we are returning
    // the size of our array list.
    return currencyModals.size();
}

// on below line we are creating our view holder class
// which will be used to initialize each view of our layout file.
public class CurrencyViewholder extends RecyclerView.ViewHolder {
    private ImageView symbolTV;
    private TextView rateTV, nameTV;

    public CurrencyViewholder(@NonNull View itemView) {
        super(itemView);
        // on below line we are initializing all
        // our text views along with its ids.

        symbolTV = itemView.findViewById(R.id.currency_logo);
        rateTV = itemView.findViewById(R.id.currency_Rate);
        nameTV = itemView.findViewById(R.id.currency_name);

    }

 }
 }

CurrencyModal

package com.example.pricepointcrypto;

public class CurrencyModal {
// variable for currency name,
// currency symbol and price.
private String name;
private int symbol;
private double price;

public CurrencyModal(String name, int symbol, double price) {
    this.name = name;
    this.symbol = symbol;
    this.price = price;
}

public String getName() {
    return name;
}

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

public int getSymbol() {
    return symbol;
}

public void setSymbol(int symbol) {
    this.symbol = symbol;
}

public double getPrice() {
    return price;
}

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

crypto_card_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
>

<androidx.cardview.widget.CardView
    android:id="@+id/currency_card"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    card_view:cardBackgroundColor="#03A9F4"
    card_view:cardCornerRadius="20dp"
    card_view:cardElevation="5dp"
    card_view:cardUseCompatPadding="true">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <ImageView
            android:id="@+id/currency_logo"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_margin="5dp"
            android:layout_weight="1"
            android:src="@drawable/ic_launcher_foreground"
            android:tag="image_tag"
            android:contentDescription="@string/currencylogo" />

        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginTop="12dp"
            android:layout_weight="2"
            android:orientation="vertical">

            <TextView
                android:id="@+id/currency_name"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="start|center_horizontal"
                android:layout_marginTop="10dp"
                android:fontFamily="casual"
                android:text="Currency Name"
                android:textAppearance="?android:attr/textAppearanceLarge"
                android:textColor="#FFEB3B"
                android:textStyle="bold" />

            <TextView
                android:id="@+id/currency_Rate"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="start|center_horizontal"
                android:layout_marginTop="0dp"
                android:fontFamily="@font/stick"
                android:text="Current Rate: "
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textColor="#FFFFFF"
                android:textColorHighlight="#FFFFFF"
                android:textStyle="bold|italic" />


        </LinearLayout>
        </LinearLayout>

   </androidx.cardview.widget.CardView>

  </LinearLayout>

Answer 1

    View view = LayoutInflater.from(context).inflate(R.layout.crypto_card_layout , parent, false);

Try setting LayoutInflater.from(parent.getContext()) instead of LayoutInflater.from(context)