I am trying to use SQLlight to favourite an object, but whenever i click the button, it gives me a null reference error.

Below is the logcat error I am getting The suggested duplicate dioesnt seem to answer my question
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean com.onyebuchboss.bossweatherbitcoinapp.SQLightHelper.insertWbapp(java.lang.String, java.lang.String)' on a null object reference
        at com.onyebuchboss.bossweatherbitcoinapp.WeatherActivity.insert(WeatherActivity.java:299)
        at com.onyebuchboss.bossweatherbitcoinapp.WeatherActivity$2.onClick(WeatherActivity.java:93)
        at android.view.View.performClick(View.java:6231)
        at android.view.View$PerformClick.run(View.java:23406)
        at android.os.Handler.handleCallback(Handler.java:836)
        at android.os.Handler.dispatchMessage(Handler.java:103)
        at android.os.Looper.loop(Looper.java:203)
        at android.app.ActivityThread.main(ActivityThread.java:6293)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1094)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)
below is the class mainClass and the last method in there is the SQLLight I called. it seems i am calling the insertData() in the wrong place:
package com.onyebuchboss.bossweatherbitcoinapp;

import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.os.Bundle;
import android.preference.PreferenceActivity;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.JsonHttpResponseHandler;
import com.loopj.android.http.RequestParams;

import org.json.JSONObject;

import cz.msebera.android.httpclient.Header;

/**
 * Created by onyeb on 22/03/2018.
 */

public class WeatherActivity extends AppCompatActivity {

    final int REQUEST_CODE = 123;
    //the openweather url to be used
    final String WEATHER_URL = "http://api.openweathermap.org/data/2.5/weather";
    //the API key
    final String APP_ID = "c9e6cb73daaf09d1bf0d1502d964bf60";
    //time between location update (5000 milliseconds or 5 seconds)
    final long MIN_TIME = 5000;
    //Distance between location in metres
    final float MIN_DISTANCE = 1000;
    final String TAG = "WeatherApp";

    //For the app to detect the user's location,
    //we set the LOCATION_PROVIDER
    String LOCATION_PROVIDER = LocationManager.GPS_PROVIDER;


    //declare the variables to be linked to the layout
    TextView mTemperature;
    TextView mCity;
    ImageView mWeatherImage;
    ImageButton FavouriteButton;


    //declare the LocationListener and LocationManager
    LocationManager mLocationManager;
    LocationListener mLocationListener;
    SQLightHelper mSQLightHelper;

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

        //Link the elements in the Layout here
        mCity = (TextView) findViewById(R.id.locationFetching);
        mTemperature = (TextView) findViewById(R.id.tempereatureView);
        mWeatherImage = (ImageView) findViewById(R.id.weatherImage);
        ImageButton ChangeCityButton = (ImageButton) findViewById(R.id.changeCityButton);
         FavouriteButton = (ImageButton) findViewById(R.id.favouriteBtn);


        //The Intent method used below is mostly used for switching between Activities
        ChangeCityButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent changeCityIntent = new Intent(WeatherActivity.this, ChangeCityController.class);
                // finish();
                startActivity(changeCityIntent);
            }
        });


    }


    //the onResume method is one of android lifecycle method
    //that starts/execute after the onCreate method
    @Override
    protected void onResume() {
        super.onResume();

        //retieving the city name passed in the
        //ChangecityController
        //City was used in the PutExtra method in changeCity
        Intent myIntent = getIntent();
        String city =myIntent.getStringExtra("City");

        //if the user does not enter a particular city
        //retrieve user current city
        if(city != null) {
            getWeatherForNewLocation(city);
        } else {
            getWeatherForCurrentLocation();
        }

        FavouriteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                insert();
            }
        });
    }

    //The method to retrieve any city entered by the user
    private void getWeatherForNewLocation(String city) {
        //the request params passes in the required parameters to retrieve data using the API
        //The openWeatherMap API being used in this project, "q" and acity's name
        //is to be assigned to iy
        RequestParams params = new RequestParams();
        params.put("q", city);
        params.put("appid", APP_ID);
        networkingCalls(params);
    }

    //  get weather situation for current city -getWeatherForCurrentCityHere()
    private void getWeatherForCurrentLocation() {
        //create an instance of LocationManager
        mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

        //the Location listener does the checking of the location for update
        mLocationListener = new LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                Log.d(TAG, "onLocationChanged: callback received");

                //get the longitude and latitude of current locaion
                //stored as a string
                String Longitude =  String.valueOf(location.getLongitude());
                String Latitude =  String.valueOf(location.getLatitude());

                Log.d(TAG, "onLocation Latitude is: " + Latitude);
                Log.d(TAG, "onLocationChanged: longitude " + Longitude);

                RequestParams params =  new RequestParams();

                params.put("lat", Latitude);
                params.put("lon", Longitude);
                params.put("appid", APP_ID);

                networkingCalls(params);

            }

            @Override
            public void onStatusChanged(String provider, int status, Bundle extras) {

            }

            @Override
            public void onProviderEnabled(String provider) {

            }

            @Override
            public void onProviderDisabled(String provider) {
                Log.d(TAG, "onProviderDisabled: callback");

            }
        };

        //REQUEST A LOCATION UPDATE PASSING THE LOCATION PROVIDER TO BE USED, MIN TIME,
        // MIN DISTANCE AND mLISTENER as the receiver
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            //request permissions to use the user's device GPS
            ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.ACCESS_FINE_LOCATION},REQUEST_CODE);
            return;
        }
        mLocationManager.requestLocationUpdates(LOCATION_PROVIDER, MIN_TIME, MIN_DISTANCE, mLocationListener);
    }


    //the override method below gives the result of the
    // permission request to use the user's GPS
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);

        //check to see if the request code matches the Request Code we gave
        //during the request
        if(requestCode == REQUEST_CODE){
            if(grantResults.length> 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
                Log.d(TAG, "onRequestPermissionsResult(): Granted!");
                getWeatherForCurrentLocation();
            }else{
                Log.d(TAG, "onRequestPermissionsResult: Permission Denied");
            }
        }
    }


    //create the networkingCalls method here
    //this method, we implement an HttpRequest, using it to make a Get request
    private void networkingCalls(RequestParams params){
        AsyncHttpClient client = new AsyncHttpClient();

        //the Json object handler is used to notify whether the Getrequest failed or was successful
        //the json response hanler receive 2 messages - onSucess and onFailure
        //both methods are declared below
        client.get(WEATHER_URL, params, new JsonHttpResponseHandler(){
            @Override
            public void onSuccess(int statusCode, Header[] headers, JSONObject response){
                Log.d(TAG, "onSuccess: " + response.toString());
                // call the json from the WeatherDataModel
                WeatherDataModel weatherData = WeatherDataModel.fromJson(response);
                updateUI(weatherData);
            }

            @Override
            public void onFailure(int statuscode, Header[] headers, Throwable e, JSONObject response){
                Log.e(TAG, "onFailure: "+ e.toString());
                Log.d(TAG, "Status code: " + statuscode);
                Toast.makeText(WeatherActivity.this, "Request failed", Toast.LENGTH_SHORT).show();

            }

        });
    }

    private void updateUI(WeatherDataModel weather){
        mTemperature.setText(weather.getTemperature());
        mCity.setText(weather.getCity());

        int resourceID = getResources().getIdentifier(weather.getIconname(), "drawable", getPackageCodePath());
        mWeatherImage.setImageResource(resourceID);
    }

    //This code below frees up memory
    //when mListener is not in use and it is automatically generated
    @Override
    protected void onPause() {
        super.onPause();

        if(mLocationManager != null) mLocationManager.removeUpdates(mLocationListener);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        getMenuInflater().inflate(R.menu.menu, menu);


        return true;
    }


    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        super.onOptionsItemSelected(item);

        if(item.getItemId() == R.id.wGoToBitcoin){
            Intent bitcoin = new Intent(WeatherActivity.this, BitcoinActivity.class);
            startActivity(bitcoin);
        }

        if(item.getItemId() == R.id.wLogOut){

            FirebaseAuth.getInstance().signOut();
            Intent logoutIntent = new Intent(WeatherActivity.this, MainActivity.class);
            startActivity(logoutIntent);

        }

        if(item.getItemId() == R.id.favourite){
            Intent favourite = new Intent(WeatherActivity.this, ListViewActivity.class);
            startActivity(favourite);
        }

        return true;
    }

    public void insert(){

         String newDegree = mTemperature.toString();
         String city = mCity.toString();
        boolean insertData = mSQLightHelper.insertWbapp(newDegree, city);
        if(insertData){
            Toast.makeText(this, "Data inserted successfully", Toast.LENGTH_SHORT).show();
        }else {
            Toast.makeText(this, "Data insertion not successful", Toast.LENGTH_SHORT).show();
        }
    }
}
And below is my SQLhelper class. Please someone help look at it.
package com.onyebuchboss.bossweatherbitcoinapp;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class SQLightHelper extends SQLiteOpenHelper {

    public static final String TABLE_NAME = "wbapp";
    public static final String COLUMN_ID = "id";
    public static final String COLUMN_A ="weather_degree";
    public static final String COLUMN_B = "city_name";

    private static final String DATABASE_NAME = "wbapp.db";
    private static final int DATABASE_VERSION = 1;

    //Creating the database
    /*private static final String DATA_CREATE = "create table " + TABLE_NAME + "( " +
    COLUMN_ID + "integer primary key autoincrement, " + COLUMN_A
    + COLUMN_ID + "integer primary key autoincrement, " + COLUMN_B + "text not null);";*/

    public SQLightHelper(Context context) {
        super(context, TABLE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table wbapp " + "(id integer primary key, weather_degree text, city_name text)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS wbapp");
        onCreate(db);
    }

    public boolean insertWbapp (String weather_degree, String city_name){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put("weather_degree", weather_degree);
        contentValues.put("city_name", city_name);

        Log.d("SQLlight", "insertWbapp: " + TABLE_NAME);
        db.insert("wbapp",null, contentValues);
        /*if(result == -1){
            return  false;}
            else {
            return true;
        }*/
        return true;
    }

    public Cursor getData(){
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor res = db.rawQuery("select * from " + TABLE_NAME, null);
        return res;
    }


    /*public  Cursor getItemID(String wDegree, String city){
        SQLiteDatabase db = this.getWritableDatabase();

        Cursor data = db.rawQuery(query, null);
        return data;
    }*/

    //delete weatherData
    public void deleteWeatherInfo (Integer id, String wDegree, String city) {
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "DELETE FROM " + TABLE_NAME + " WHERE " + COLUMN_ID + " = '" + id + "'" +
                " AND "  + COLUMN_A + " = '" + wDegree + "'" + " AND "  + COLUMN_B + " = '" + city + "'";

        Log.d("SQLIGHTHELPER", "deleteWeatherInfo: " + wDegree + city + "from the datbase");

        db.execSQL(query);
    }

}
I do not know what I am doing wrong. Someone please help