java.lang.String android.content.Context.getPackageName（） 在空对象引用上

问：

我努力寻找我的代码的问题，但到目前为止我不是很幸运。谁能帮我解决它？ 它被认为是一个儿童游戏，可以为显示的动物指定正确的名字。在原始文件中，图片被存储，在文本文件中，“AnimalNames”的每一行都有相应的动物名称。

代码如下：

package com.example.tiereraten;

import androidx.appcompat.app.AppCompatActivity;

import android.content.res.AssetManager;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;

public class MainActivity extends AppCompatActivity {
    Button button01, button02, button03, button04;
    ImageView imageView;
    ArrayList<String> animalNames = new ArrayList<String>();
    ArrayList<Integer> animalPics = new ArrayList<Integer>();
    Integer chosenAnimal = 0;
    Integer locationOfCorrectAnswer, score, numberOfQuestion;
    TextView resultTextView, scoreTextView;
    String animalNamesText = "AnimalNames.txt";
    ArrayList<String>answers = new ArrayList<String>(4);
    // Get the Resources object
    Resources res ;
    AssetManager assetManager;

    // Get the package name of your app
    String packageName = getPackageName();

    // Get the identifier of the drawable folder
    int rawId;

    // Get an array of all the drawable resource IDs
    TypedArray images;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button01 = findViewById(R.id.button01);
        button02 = findViewById(R.id.button02);
        button03 = findViewById(R.id.button03);
        button04 = findViewById(R.id.button04);
        imageView = findViewById(R.id.animalImageView);
        resultTextView = findViewById(R.id.resultTextView);
        scoreTextView = findViewById(R.id.scoreTextView);
        res = getResources();
        rawId = res.getIdentifier("raw", "raw", packageName);
        images = res.obtainTypedArray(rawId);
        for (int i = 0; i < images.length(); i++) {
            int resourceId = images.getResourceId(i, -1);
            if (resourceId != -1) {
                animalPics.add(resourceId);
            }
        }
        try {
            // Get the InputStream for the text file
            InputStream inputStream = getAssets().open(animalNamesText);

            // Create a new InputStreamReader to read the text file
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);

            // Create a new BufferedReader to read the text file line by line
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

            // Read each line of the text file and add it to the ArrayList
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                animalNames.add(line);
            }

            // Close the BufferedReader
            bufferedReader.close();
        } catch (IOException e) {
            // Handle the exception
            e.printStackTrace();
        }

        reset(scoreTextView);

    }
    public void newQuestion(){
            resultTextView.setText("Welches Tier ist es?");
            Random rnd = new Random();
            locationOfCorrectAnswer = rnd.nextInt(4);
            chosenAnimal = rnd.nextInt(animalPics.size());
            int resourceId = animalPics.get(chosenAnimal);
            imageView.setImageResource(resourceId);
            answers = new ArrayList<String>(Arrays.asList("", "", "", ""));
            for (int i = 0; i < 4; i++) {
                if (i == locationOfCorrectAnswer) {
                    answers.add(animalNames.get(chosenAnimal));
                } else {
                    int wrongAnswerLocation = rnd.nextInt(animalNames.size());
                    while (wrongAnswerLocation == chosenAnimal) {
                        wrongAnswerLocation = rnd.nextInt(animalNames.size());
                    }
                    answers.set(i, animalNames.get(wrongAnswerLocation));
                    Log.i("Chosen wrong animalName", animalNames.get(wrongAnswerLocation));

                }
            }
            button01.setText(answers.get(0));
            Log.i("answer(0)",answers.get(0));
            button02.setText(answers.get(1));
            Log.i("answer(1)",answers.get(1));
            button03.setText(answers.get(2));
            Log.i("answer(2)",answers.get(2));
            button04.setText(answers.get(3));
            Log.i("answer(3)",answers.get(3));

    }

    public void choseAnswer (View view){
        if(Integer.toString(locationOfCorrectAnswer).equals(view.getTag().toString())){
            resultTextView.setText("Korrekt!");
            score++;

        }else{
            resultTextView.setText("falsch");

        }
        try {
            Thread.sleep(1000); // Sleep for one second (1000 milliseconds)
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        numberOfQuestion++;
        scoreTextView.setText(Integer.toString(score)  +"/"+ Integer.toString(numberOfQuestion));
        newQuestion();
    }
    public void reset (View view){
        score = 0;
        numberOfQuestion = 0;
        scoreTextView.setText(Integer.toString(score)  +"/"+ Integer.toString(numberOfQuestion));
        newQuestion();
    }
}

我尝试在旧的 adroid 手机（棒棒糖版本 22）上调试并运行它。不幸的是，我无法在虚拟设备上运行它。