Я создаю приложение, которое подключается к REST API и извлекает всех сотрудников из базы данных. Приложение использует RecyclerView для отображения всех сотрудников, которые возвращаются в CardView. Проблема в том, что в RecyclerView ничего не появляется, и есть данные, которые возвращаются из REST API.
Это Android-приложение, построенное на Java, использующее Pie для ОС. Проект был создан с использованием базового шаблона действий.
Мой класс занятий
public class ViewAllEmployees extends AppCompatActivity {
private List<Employee> employees;
private RecyclerView rcView;
private EmployeeAdapter adapter;
private Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_all_employees);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
context = this;
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
FetchEmployeesTask async = new FetchEmployeesTask(new AsyncResponse() {
@Override
public void processFinished(List<Employee> output) {
Log.i("Async", "Finished");
}
});
async.execute();
rcView = findViewById(R.id.rcView);
adapter = new EmployeeAdapter(context, employees);
rcView.setAdapter(adapter);
rcView.setLayoutManager(new LinearLayoutManager(context));
}
private class FetchEmployeesTask extends AsyncTask<Void, Void, List<Employee>> {
public AsyncResponse delegate = null;
public FetchEmployeesTask(AsyncResponse asyncResponse){
delegate = asyncResponse;
}
@Override
protected List<Employee> doInBackground(Void... voids) {
return new APIHelper().fetchItems();
}
@Override
protected void onPostExecute(List<Employee> items) {
employees = items;
delegate.processFinished(items);
}
}
public interface AsyncResponse{
void processFinished(List<Employee> output);
}
}
Адаптер сотрудника для RecyclerView
public class EmployeeAdapter extends RecyclerView.Adapter<EmployeeAdapter.EmployeeViewHolder> {
private List<Employee> employees;
private final LayoutInflater mInflater;
private Context context;
public int position;
public EmployeeAdapter(Context context, List<Employee> employeeList){
this.context = context;
employees = new ArrayList<>();
mInflater = LayoutInflater.from(context);
employees = employeeList;
}
@NonNull
@Override
public EmployeeViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View mItemView = mInflater.inflate(R.layout.employee_card, viewGroup, false);
return new EmployeeViewHolder(mItemView, this);
}
@Override
public void onBindViewHolder(@NonNull EmployeeViewHolder employeeViewHolder, int i) {
Employee empl = employees.get(i);
employeeViewHolder.name.setText(empl.firstName + empl.lastName);
employeeViewHolder.department.setText(empl.department);
}
@Override
public int getItemCount() {
return employees == null ? 0 : employees.size();
}
class EmployeeViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public final TextView name;
public final TextView department;
private EmployeeAdapter adapter;
private final CardView card;
public EmployeeViewHolder(View itemView, EmployeeAdapter adapter) {
super(itemView);
name = itemView.findViewById(R.id.txtName);
department = itemView.findViewById(R.id.txtDepartment);
card = itemView.findViewById(R.id.cv);
itemView.setOnClickListener(this);
this.adapter = adapter;
}
@Override
public void onClick(View view) {
}
}
}
Класс APIHelper
public class APIHelper {
private static final String ENDPOINT = "ENDPOINTADDRESS";
private static final String TAG = "APIHelper";
public byte[] getUrlBytes(String urlSpec) throws IOException{
URL url = new URL(urlSpec);
HttpURLConnection connection = (HttpURLConnection)url.openConnection();
try{
ByteArrayOutputStream out = new ByteArrayOutputStream();
InputStream in = connection.getInputStream();
if(connection.getResponseCode() != HttpURLConnection.HTTP_OK){
return null;
}
int bytesRead = 0;
byte[] buffer = new byte[1024];
while((bytesRead = in.read(buffer)) > 0){
out.write(buffer, 0, bytesRead);
}
out.close();
return out.toByteArray();
}
finally {
connection.disconnect();
}
}
public String getUrlString(String urlSpec) throws IOException{
return new String((getUrlBytes(urlSpec)));
}
private void parseItems(List<Employee> employees, JSONArray jsonBody) throws IOException, JSONException {
JSONArray employeeArray = jsonBody;
for(int i = 0; i < employeeArray.length(); i++){
JSONObject jsonEmployee = employeeArray.getJSONObject(i);
JSONObject job = jsonEmployee.getJSONObject("Job");
Employee emp = new Employee();
//emp.setDepartment(jsonEmployee.getString("DepartmentId"));
emp.setEmail(jsonEmployee.getString("EmailAddress"));
emp.setEmployeeID(jsonEmployee.getString("EmployeeID"));
emp.setFirstName(jsonEmployee.getString("FirstName"));
emp.setLastName(jsonEmployee.getString("LastName"));
emp.setMiddleInitial(jsonEmployee.getString("MiddleInitial"));
emp.setPosition(job.getString("JobTitle"));
emp.setWorkNumber(jsonEmployee.getString("WorkNumber"));
employees.add(emp);
}
}
public List<Employee> fetchItems(){
List<Employee> employees = new ArrayList<>();
try{
String url = Uri.parse(ENDPOINT).buildUpon().build().toString();
String jsonString = getUrlString(url);
Log.i(TAG, "Received JSON: " + jsonString);
JSONArray jsonBody = new JSONArray(jsonString);
parseItems(employees, jsonBody);
}
catch (IOException ioe){
Log.e(TAG, "Failed to fetch items", ioe);
}
catch (JSONException je){
Log.e(TAG, "Failed to parse json:", je);
}
return employees;
}
Макет для ViewAllEmployees
<?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"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".ViewAllEmployees"
tools:showIn="@layout/activity_view_all_employees">
<android.support.v7.widget.RecyclerView
android:id="@+id/rcView"
android:layout_width="395dp"
android:layout_height="659dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
Просмотр карты, который находится в Recyclerview
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:padding="16dp">
<android.support.v7.widget.CardView
android:id="@+id/cv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
app:cardElevation="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/txtName"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Name"/>
<TextView
android:id="@+id/txtDepartment"
android:layout_width="match_parent"
android:layout_height="127dp"
android:layout_below="@+id/txtName"
android:layout_alignEnd="@+id/txtName"
android:layout_marginTop="-142dp"
android:layout_marginEnd="0dp" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
Когда приложение запускается, RecyclerView должен заполняться CardViews, которые отображают имя сотрудника и его отдел. Однако в настоящее время он ничего не отображает.