java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.pets/com.example.android.pets.CatalogActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'int android.database.Cursor.getCount()' on a null object reference

CatalogActivity

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.pets;

import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;

import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_BREED;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_GENDER;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_NAME;
import static com.example.android.pets.data.PetContract.PetEntry.COLUMN_PET_WEIGHT;
import static com.example.android.pets.data.PetContract.PetEntry.CONTENT_URI;
import static com.example.android.pets.data.PetContract.PetEntry.GENDER_MALE;
import static com.example.android.pets.data.PetContract.PetEntry._ID;

/**
 * Displays list of pets that were entered and stored in the app.
 */
public class CatalogActivity extends AppCompatActivity {

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

        // Setup FAB to open EditorActivity
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(CatalogActivity.this, EditorActivity.class);
                startActivity(intent);
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        displayDatabaseInfo();
    }

    /**
     * Temporary helper method to display information in the onscreen TextView about the state of
     * the pets database.
     */

    private void displayDatabaseInfo() {
        // Define a projection that specifies which columns from the database
        // you will actually use after this query.
        String[] projection = {_ID,
                                COLUMN_PET_NAME,
                                COLUMN_PET_BREED,
                                COLUMN_PET_GENDER,
                                COLUMN_PET_WEIGHT};

        // Perform a query on the provider using the ContentResolver.
        // Use the {"link PetEntry#CONTENT_URI} to access the pet data.
        Cursor cursor = getContentResolver().query(CONTENT_URI, // The content URI of the words table
                                                    projection, // The content URI with the words fill
                                                    null, // Selection criteria
                                                    null,   // Selection criteria
                                                     null); // The sort order for the returned rows.

        TextView displayView = (TextView) findViewById(R.id.text_view_pet);
        try {
            // Create a header in the Text View that looks like this:
            //
            // The pets table contains <number of rows in Cursor> pets
            // _id - name - breed - gender - weight
            //
            // IN the while loop below, iterate through the rows of the cursor and display the information
            // from each column in this order
            displayView.setText("The pets table contains " + cursor.getCount() + " pets.\n\n");
            displayView.append(_ID + " - " +
                    COLUMN_PET_NAME + " - " +
                    COLUMN_PET_BREED + " - " +
                    COLUMN_PET_GENDER + " - " +
                    COLUMN_PET_WEIGHT + "\n");

            // Figure out the index of each column
            int idColumnIndex = cursor.getColumnIndex(_ID);
            int nameColumnIndex = cursor.getColumnIndex(COLUMN_PET_NAME);
            int breedColumnIndex = cursor.getColumnIndex(COLUMN_PET_BREED);
            int genderColumnIndex = cursor.getColumnIndex(COLUMN_PET_GENDER);
            int weightColumnIndex = cursor.getColumnIndex(COLUMN_PET_WEIGHT);

            // Iterate through all the returned rows in the cursor.
            while (cursor.moveToNext()) {
                //Use that index to extract the String or int value of the word
                // at the current row the cursor is on.
                int currentID = cursor.getInt(idColumnIndex);
                String currentName = cursor.getString(nameColumnIndex);
                String currentBreed = cursor.getString(breedColumnIndex);
                int currentGender = cursor.getInt(genderColumnIndex);
                int currentWeight = cursor.getInt(weightColumnIndex);
                //Display the values from each column of the current row in the cursor in the TextView
                displayView.append(("\n" + currentID + " - " +
                        currentName + " - " +
                        currentBreed + " - " +
                        currentGender + " - " +
                        currentWeight));
            }
        } finally {
            // Always close the cursor when you're done reading from it. This releases all its
            // resources and makes it invalid.
            cursor.close();
        }
    }

    private void insertPet() {

        ContentValues values = new ContentValues();
        values.put(COLUMN_PET_NAME, "Toto");
        values.put(COLUMN_PET_BREED, "Terrier");
        values.put(COLUMN_PET_GENDER, GENDER_MALE);
        values.put(COLUMN_PET_WEIGHT, 7);

        Uri newUri = getContentResolver().insert(CONTENT_URI, values);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu options from the res/menu/menu_catalog.xml file.
        // This adds menu items to the app bar.
        getMenuInflater().inflate(R.menu.menu_catalog, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // User clicked on a menu option in the app bar overflow menu
        switch (item.getItemId()) {
            // Respond to a click on the "Insert dummy data" menu option
            case R.id.action_insert_dummy_data:
                insertPet();
                displayDatabaseInfo();
                return true;
            // Respond to a click on the "Delete all entries" menu option
            case R.id.action_delete_all_entries:
                // Do nothing for now
                return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

In my PetsApp, the android Run monitor keeps showing me this error.

@dagger
@Alex_234
This is the CatalogActivity for the pets app.
Please this code is giving me an issue as shown in the Android monitor. Please could you help out with it.

How can u use content provider without contract class . I think you need to define it .