Android ProgrssBar不'；t显示在屏幕上

我想在上传数据到DB时在屏幕上设置可见进度条。但当我把可视的，它不会显示在我的屏幕上。怎么了？ 这是我的活动课

 public class MainActivity extends AppCompatActivity {

        private CountryService countryService = new CountryServiceImpl();
        private static final String INSERT_DATA_ITEM_MESSAGE = "Insert data item selected";
        private static final String EXIT_ITEM_MESSAGE = "Exit. Bye, bye";
        private static final String ERROR_DURING_CONVERTING_JSON_TO_MAP_MESSAGE = "Error during converting JSON to Map. ";
        private static final String JSON_FILE_NAME = "countries";
        private static final String ASSET_FOLDER = "raw";
        private static final String DATA_ARE_ALREADY_UPLOADED = "Data are already uploaded";
        private static final String DATA_UPLOADED_SUCCESSFUL = "Data uploaded successful";
        private static final String KEYWORD = "search";
        private SQLiteDatabase sqLiteDatabase;
        private SQLiteConnector sqLiteConnector;
        private Spinner countryListSpinner;
        private ListView listView;
        private List<CountryWithCitiesDto> listCountryiesAndCities;
        private ProgressBar progressBar;

        private Map<String, String[]> getParsedMapFromJSONFile() {
            InputStream inputStream = getResources().openRawResource(
                    getResources().getIdentifier(JSON_FILE_NAME,
                            ASSET_FOLDER, getPackageName()));
            byte[] byteArrayFromJSONFile = JSONReader.getByteArrayFromJsonFile(inputStream);
            if (byteArrayFromJSONFile != null) {
                return buildMapFromByteArrayJSONFile(byteArrayFromJSONFile);
            }
            return Collections.emptyMap();
        }


        private Map<String, String[]> buildMapFromByteArrayJSONFile(byte[] jsonByteArray) {
            try {
                ObjectMapper mapper = new ObjectMapper();
                return mapper.readValue(jsonByteArray, new TypeReference<Map<String, String[]>>() {
                });
            } catch (IOException e) {
                Log.e(ClassNameTags.MAIN_ACTIVITY, ERROR_DURING_CONVERTING_JSON_TO_MAP_MESSAGE + e.getMessage());
                return Collections.emptyMap();
            }
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            initDatabase();
            countryListSpinner = (Spinner) findViewById(R.id.countryListSpinner);
            progressBar = (ProgressBar) findViewById(R.id.progressBar);
            listView = (ListView) findViewById(R.id.cityListView);
            progressBar.setVisibility(View.VISIBLE);
            setAdapterToSpinner(setCountryListSpinner());
            progressBar.setVisibility(View.INVISIBLE);
            countryListSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> arg0, View arg1,
                                           int position, long arg3) {
                    List<String> cityList = new ArrayList<>();
                    for (int i = 0; i < listCountryiesAndCities.get(position).getCityList().size(); i++) {
                        cityList.add(listCountryiesAndCities.get(position).getCityList().get(i).getNameCity());
                    }
                    setAdapterToCityList(cityList);
                }


                @Override
                public void onNothingSelected(AdapterView<?> arg0) {


                }
            });


            listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position,
                                        long id) {
                    Intent intent = new Intent(MainActivity.this, WikiActivity.class);
                    intent.putExtra(KEYWORD, listCountryiesAndCities.get((int) countryListSpinner.getSelectedItemId()).getCityList().get(position).getNameCity());
                    startActivity(intent);
                }
            });
        }


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

        @Override
        public boolean onOptionsItemSelected(MenuItem item) {
            switch (item.getItemId()) {
                case R.id.insert_data_menu:
                    if (listCountryiesAndCities.isEmpty()) {
                        progressBar.setVisibility(View.VISIBLE);
                        uploadFromJsonToDatabase();
                        setAdapterToSpinner(setCountryListSpinner());
                        progressBar.setVisibility(View.INVISIBLE);
                        Toast.makeText(this, DATA_UPLOADED_SUCCESSFUL, Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(this, DATA_ARE_ALREADY_UPLOADED, Toast.LENGTH_SHORT).show();
                    }
                    Log.i(ClassNameTags.MAIN_ACTIVITY, INSERT_DATA_ITEM_MESSAGE);
                    break;
                case R.id.exit_menu:
                    Log.i(ClassNameTags.MAIN_ACTIVITY, EXIT_ITEM_MESSAGE);
                    break;
            }
            return super.onOptionsItemSelected(item);
        }


        private void initDatabase() {
            sqLiteConnector = new SQLiteConnector(this);
            sqLiteDatabase = sqLiteConnector.getWritableDatabase();
        }

        private void uploadFromJsonToDatabase() {
            countryService.insertCountryWithCities(getParsedMapFromJSONFile(), sqLiteDatabase);
        }

        private String[] setCountryListSpinner() {
            listCountryiesAndCities = countryService.getListCountriesWithCities(sqLiteDatabase);
            String[] outArray = new String[listCountryiesAndCities.size()];
            for (int i = 0; i < listCountryiesAndCities.size(); i++) {
                System.out.println(listCountryiesAndCities.get(i).getCountry().getNameCountry());
                outArray[i] = listCountryiesAndCities.get(i).getCountry().getNameCountry();
            }
            return outArray;
        }

        private void setAdapterToSpinner(String[] spinnerCountryArray) {
            ArrayAdapter<String> adapter = new ArrayAdapter<>(this,
                    android.R.layout.simple_spinner_item, spinnerCountryArray);
            countryListSpinner.setAdapter(adapter);
        }


        private void setAdapterToCityList(List<String> cityNames) {
            ArrayAdapter<String> adapterToCityList
                    = new ArrayAdapter<>(this,
                    android.R.layout.simple_list_item_1,
                    cityNames);
            listView.setAdapter(adapterToCityList);
            adapterToCityList.notifyDataSetChanged();

        }


    }

public类MainActivity扩展了AppCompatActivity{
private CountryService CountryService=new countryserviceinpl（）；
私有静态最终字符串INSERT\u DATA\u ITEM\u MESSAGE=“INSERT DATA ITEM selected”；
私有静态最终字符串EXIT\u ITEM\u MESSAGE=“EXIT.Bye，Bye”；
私有静态最终字符串错误\u在将\u JSON\u转换为\u MAP时\u MESSAGE=“将JSON转换为MAP时出错。”；
私有静态最终字符串JSON_FILE_NAME=“countries”；
私有静态最终字符串ASSET\u FOLDER=“raw”；
私有静态最终字符串数据已上传=“数据已上传”；
私有静态最终字符串数据上传成功=“数据上传成功”；
私有静态最终字符串关键字=“搜索”；
专用SQLiteDatabase SQLiteDatabase；
专用SQLiteConnector SQLiteConnector；
私人微调器；
私有列表视图列表视图；
私人名单国家和城市；
私人ProgressBar ProgressBar；
私有映射getParsedMapFromJSONFile（）{
InputStream InputStream=getResources（）.openRawResource(
getResources（）.getIdentifier（JSON文件名，
资产_文件夹，getPackageName（））；
字节[]byteArrayFromJSONFile=JSONReader.getByteArrayFromJsonFile（inputStream）；
if（byteArrayFromJSONFile！=null）{
从ByteArrayJSonfile（byteArrayFromJSONFile）返回BuildMap；
}
return Collections.emptyMap（）；
}
私有映射buildMapFromByteArray JSonfile（字节[]jsonByteArray）{
试一试{
ObjectMapper mapper=新的ObjectMapper（）；
返回mapper.readValue（jsonByteArray，newTypeReference（）{
});
}捕获（IOE异常）{
Log.e（ClassNameTags.MAIN_活动，将_JSON_转换为_MAP_MESSAGE+e.getMessage（）时出错）；
return Collections.emptyMap（）；
}
}
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
initDatabase（）；
countryListSpinner=（Spinner）findViewById（R.id.countryListSpinner）；
progressBar=（progressBar）findViewById（R.id.progressBar）；
listView=（listView）findViewById（R.id.cityListView）；
progressBar.setVisibility（View.VISIBLE）；
setAdapterToSpinner（setCountryListSpinner（））；
progressBar.setVisibility（View.INVISIBLE）；
countryListSpinner.setOnItemSelectedListener（新的AdapterView.OnItemSelectedListener（）{
@凌驾
已选择公共视图（AdapterView arg0、视图arg1、，
整数位置，长arg3）{
List cityList=new ArrayList（）；
for（int i=0；i<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.shapoval.countryparser.MainActivity">


    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:layout_constraintTop_creator="1"
        android:layout_marginStart="124dp"
        android:layout_marginTop="-326dp"
        tools:layout_constraintLeft_creator="1"
        app:layout_constraintLeft_toLeftOf="@+id/cityListView"
        app:layout_constraintTop_toTopOf="@+id/cityListView"
        android:layout_marginLeft="-166dp" />

    <Spinner
        android:id="@+id/countryListSpinner"
        android:layout_width="303dp"
        android:layout_height="48dp"
        android:layout_marginEnd="47dp"
        android:layout_marginRight="47dp"
        app:layout_constraintRight_toRightOf="parent"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintTop_creator="1"
        tools:layout_constraintBottom_creator="1"
        app:layout_constraintBottom_toTopOf="@+id/cityListView"
        android:layout_marginBottom="22dp"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_marginTop="25dp" />

    <ListView
        android:layout_width="0dp"
        android:layout_height="361dp"
        android:id="@+id/cityListView"
        tools:layout_constraintRight_creator="1"
        tools:layout_constraintBottom_creator="1"
        android:layout_marginStart="31dp"
        app:layout_constraintBottom_toBottomOf="parent"
        android:layout_marginEnd="31dp"
        app:layout_constraintRight_toRightOf="parent"
        tools:layout_constraintLeft_creator="1"
        android:layout_marginBottom="55dp"
        app:layout_constraintLeft_toLeftOf="parent" />
</android.support.constraint.ConstraintLayout>