Android Studio-自定义ListView崩溃应用程序

我有一个定制的listview,目的是获取JSON数据并将其显示给用户,但是每当我调用它时,它都会崩溃。

主班

public class Main extends AppCompatActivity {

//Change Activity
//Log Out
public void OpenBeginningActivity(){
    Intent intent = new Intent(this, Beginning.class);
    startActivity(intent);
}

//Take Picture
public void TakePicture(){
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    startActivityForResult(intent,0);
}

//JSON Variables
final String TAG = Main.class.getSimpleName();
final String JSONUrl = "http://iameuropeapp.pythonanywhere.com/getcountries";
private ArrayList<Country> CountryList;

//Variables
private ProgressDialog ProgressDialog;
private String UserEmail;
private FirebaseAuth FirebaseInstance;
private FirebaseAuth FirebaseAuthentication;
private FirebaseUser LoggedInUser;
private TextView UserEmailText;
private ListView CountryListView;
private ListAdapter Adapter;

public void ParseJSON(View view){

}

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

    //Change Bar Title
    getSupportActionBar().setTitle("Dashboard");

    //Get Components
    UserEmailText = (TextView)findViewById(R.id.UserEmail);
    FirebaseInstance = FirebaseAuthentication.getInstance();
    LoggedInUser = FirebaseInstance.getCurrentUser();

    //Set Username
    UserEmailText.setText(LoggedInUser.getEmail());

    //ListView
    CountryList = new ArrayList<>();
    CountryListView = (ListView) findViewById(R.id.CountryList);

    //Countries
    new GetCountries().execute();
}

public boolean onCreateOptionsMenu(Menu menu){
    getMenuInflater().inflate(R.menu.main_menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    //Take Photo
    if(item.getItemId() == R.id.MenuItem1){
        TakePicture();
    }

    //Sign Out
    else if(item.getItemId() == R.id.MenuItem2){
        FirebaseAuthentication.getInstance().signOut();
        OpenBeginningActivity();
        ProgressDialog.setMessage("Signing out...");
        ProgressDialog.show();
    }

    return super.onOptionsItemSelected(item);
}

private class GetCountries extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        ProgressDialog = new ProgressDialog(Main.this);
        ProgressDialog.setMessage("Please wait...");
        ProgressDialog.show();
    }

    @Override
    protected Void doInBackground(Void... voids) {
        HttpHandler Handler = new HttpHandler();
        String JSONString = Handler.makeServiceCall(JSONUrl);
        Log.e(TAG, "Response:" + JSONString);

        if(JSONString != null){
            try {
                JSONObject CountriesJSONObject = new JSONObject(JSONString);
                JSONArray Countries = CountriesJSONObject.getJSONArray("countries");

                for (int i = 0; i < Countries.length(); i++) {
                    JSONObject Country = Countries.getJSONObject(i).getJSONObject("country");
                    String CountryID = Country.getString("id");
                    String CountryName = Country.getString("name");
                    String CountryImage = Country.getString("image");
                    CountryList.add(new Country(CountryID, CountryName, CountryImage));
                }
            } catch (final JSONException e){
                Log.e(TAG,e.getMessage());
                ProgressDialog.setMessage("Error loading Data!");
            }
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void Result)
    {
        ProgressDialog.dismiss();
        ListAdapter CustomAdapter = new CustomAdapter(Main.this,0,CountryList);
        CountryListView.setAdapter(CustomAdapter);

    }

}

}

自定义适配器

public class CustomAdapter extends ArrayAdapter<Country>{

public ArrayList<Country> ArrayListCountries;

public CustomAdapter(@NonNull Context context,int resource, ArrayList<Country> Countries) {
    super(context, R.layout.activity_main_list, Countries);
}

@Override
public View getView(int Position, View view, ViewGroup viewgroup){
    //Init
    LayoutInflater Inflater = LayoutInflater.from(getContext());
    View CustomView = Inflater.inflate(R.layout.activity_main_list, viewgroup, false);

    //Get Components
    Country country = ArrayListCountries.get(Position);
    TextView CountryText = (TextView) CustomView.findViewById(R.id.CountryNameText);
    ImageView CountryImage = (ImageView) CustomView.findViewById(R.id.CountryImage);

    //Set Values
    CountryText.setText(country.name);

    //End
    return CustomView;
}
}

国家级

public class Country {
public String id, name, image;

public Country (String id, String name, String image) {
    this.id = id;
    this.name = name;
    this.image = image;
}
}

这是当前阻止我继续的唯一问题,因为在此之后出现的功能要求用户访问ListView。我一整天都在努力使这项工作真正发挥作用。