Java tutorial
/* * Copyright (C) 2014 barter.li * * 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 li.barter.fragments; import android.app.Activity; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.support.v7.app.ActionBarActivity; import android.text.TextUtils; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.view.WindowManager; import android.widget.CheckBox; import android.widget.CompoundButton; import android.widget.CompoundButton.OnCheckedChangeListener; import android.widget.EditText; import com.android.volley.Request.Method; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.util.HashMap; import java.util.List; import java.util.Map; import li.barter.R; import li.barter.activities.AbstractBarterLiActivity.AlertStyle; import li.barter.activities.AuthActivity; import li.barter.analytics.AnalyticsConstants.Screens; import li.barter.data.DBInterface; import li.barter.data.DBInterface.AsyncDbQueryCallback; import li.barter.data.DatabaseColumns; import li.barter.data.SQLConstants; import li.barter.data.TableUserBooks; import li.barter.http.BlRequest; import li.barter.http.HttpConstants; import li.barter.http.HttpConstants.ApiEndpoints; import li.barter.http.HttpConstants.GoogleBookSearchKey; import li.barter.http.HttpConstants.RequestId; import li.barter.http.IBlRequestContract; import li.barter.http.ResponseInfo; import li.barter.utils.AppConstants; import li.barter.utils.AppConstants.BarterType; import li.barter.utils.AppConstants.Keys; import li.barter.utils.AppConstants.QueryTokens; import li.barter.utils.Logger; import li.barter.utils.Utils; import li.barter.widgets.autocomplete.INetworkSuggestCallbacks; import li.barter.widgets.autocomplete.NetworkedAutoCompleteTextView; import li.barter.widgets.autocomplete.Suggestion; @FragmentTransition(enterAnimation = R.anim.slide_in_from_right, exitAnimation = R.anim.zoom_out, popEnterAnimation = R.anim.zoom_in, popExitAnimation = R.anim.slide_out_to_right) public class AddOrEditBookFragment extends AbstractBarterLiFragment implements AsyncDbQueryCallback, INetworkSuggestCallbacks, OnCheckedChangeListener { private static final String TAG = "AddOrEditBookFragment"; private EditText mIsbnEditText; private NetworkedAutoCompleteTextView mTitleEditText; private EditText mAuthorEditText; private EditText mDescriptionEditText; private EditText mSellPriceEditText; private CheckBox mBarterCheckBox; private CheckBox mSellCheckBox; private CheckBox mLendCheckBox; private CheckBox[] mBarterTypeCheckBoxes; private String mIsbnNumber; private boolean mHasFetchedDetails; private boolean mEditMode; private String mId; private String mImage_Url; private String mPublicationYear; private String mGoogleBooksApiKey; private final String mBookSelection = DatabaseColumns.ID + SQLConstants.EQUALS_ARG; /** * Whether a upload request is happening */ private boolean mIsUpoading; @Override public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) { init(container, savedInstanceState); setHasOptionsMenu(true); setActionBarTitle(R.string.editbook_title); final View view = inflater.inflate(R.layout.fragment_add_or_edit_book, container, false); initViews(view); mGoogleBooksApiKey = getString(R.string.google_maps_v2_api_key); getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE | WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN); final Bundle extras = getArguments(); // If extras are null, it means that user has to decided to add the // book completely manually if (extras != null) { mEditMode = extras.getBoolean(Keys.EDIT_MODE); if (mEditMode) { mId = extras.getString(Keys.ID); setActionBarTitle(R.string.editbook_title2); //Reached here by editing current user's book loadBookDetails(QueryTokens.LOAD_BOOK_DETAIL_FOR_EDIT, mId); } else { mIsbnNumber = extras.getString(Keys.ISBN); Logger.d(TAG, "Book Isbn:" + mIsbnNumber); if (savedInstanceState != null) { mHasFetchedDetails = savedInstanceState.getBoolean(Keys.HAS_FETCHED_INFO); } else { loadDetailsForIntent(extras); } if (!mHasFetchedDetails && !TextUtils.isEmpty(mIsbnNumber)) { getBookInfoFromServer(mIsbnNumber); } } } return view; } /** * Load the details of a particular book * * @param queryToken The Query token to use after the load callback returns * @param bookId The id of the book to load */ private void loadBookDetails(final int queryToken, final String bookId) { DBInterface.queryAsync(queryToken, getTaskTag(), null, false, TableUserBooks.NAME, null, mBookSelection, new String[] { bookId }, null, null, null, null, this); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.menu_add_or_edit_book, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == R.id.action_save && !mIsUpoading) { checkAndFinishBookSubmitTask(); return true; } else { return super.onOptionsItemSelected(item); } } /** * Does the job of checking if user is logged in and finishes the book add/update process */ private void checkAndFinishBookSubmitTask() { if (isInputValid()) { if (!isLoggedIn()) { final Intent loginIntent = new Intent(getActivity(), AuthActivity.class); getActivity().startActivityForResult(loginIntent, AppConstants.RequestCodes.LOGIN_TO_ADD_BOOK); } else { if (mEditMode) { mIsUpoading = true; updateBookOnServer(null); } else { if (hasFirstName()) { mIsUpoading = true; createBookOnServer(null); } else { showAddFirstNameDialog(); } } } } } /** * Gets references to the Views * * @param view The content view of the fragment */ private void initViews(final View view) { mIsbnEditText = (EditText) view.findViewById(R.id.edit_text_isbn); mTitleEditText = (NetworkedAutoCompleteTextView) view.findViewById(R.id.edit_text_title); mTitleEditText.setNetworkSuggestCallbacks(this); mTitleEditText.setSuggestCountThreshold(3); mTitleEditText.setSuggestWaitThreshold(400); mAuthorEditText = (EditText) view.findViewById(R.id.edit_text_author); mDescriptionEditText = (EditText) view.findViewById(R.id.edit_text_description); mSellPriceEditText = (EditText) view.findViewById(R.id.edit_sell_price); initBarterTypeCheckBoxes(view); } /** * Gets the references to the barter type checkboxes, set the tags to simplify building the tags * array when sending the request to server * * @param view The content view of the fragment */ private void initBarterTypeCheckBoxes(final View view) { mBarterCheckBox = (CheckBox) view.findViewById(R.id.checkbox_barter); mSellCheckBox = (CheckBox) view.findViewById(R.id.checkbox_sell); mLendCheckBox = (CheckBox) view.findViewById(R.id.checkbox_lend); // Set the barter tags mBarterCheckBox.setTag(R.string.tag_barter_type, BarterType.BARTER); mSellCheckBox.setTag(R.string.tag_barter_type, BarterType.SALE); mLendCheckBox.setTag(R.string.tag_barter_type, BarterType.LEND); mSellCheckBox.setOnCheckedChangeListener(this); mBarterTypeCheckBoxes = new CheckBox[3]; mBarterTypeCheckBoxes[0] = mBarterCheckBox; mBarterTypeCheckBoxes[1] = mSellCheckBox; mBarterTypeCheckBoxes[2] = mLendCheckBox; } @Override public void onSaveInstanceState(final Bundle outState) { super.onSaveInstanceState(outState); outState.putBoolean(Keys.HAS_FETCHED_INFO, mHasFetchedDetails); } /** * @param args The Fragment arguments */ private void loadDetailsForIntent(final Bundle args) { mIsbnNumber = args.getString(Keys.ISBN); final String title = args.getString(Keys.BOOK_TITLE); final String author = args.getString(Keys.AUTHOR); final String description = args.getString(Keys.DESCRIPTION); final List<String> barterTypes = args.getStringArrayList(Keys.BARTER_TYPES); mIsbnEditText.setText(mIsbnNumber); mTitleEditText.setTextWithFilter(title, false); mAuthorEditText.setText(author); mDescriptionEditText.setText(description); setCheckBoxesForBarterTypes(barterTypes); } @Override protected Object getTaskTag() { return hashCode(); } /** * Fetches the book info from server based on the ISBN number or book title * * @param isbn The ISBN Number of the book to get info for */ private void getBookInfoFromServer(final String isbn) { final BlRequest request = new BlRequest(Method.GET, HttpConstants.getGoogleBooksUrl() + ApiEndpoints.VOLUMES, null, mVolleyCallbacks); request.setRequestId(RequestId.GET_BOOK_INFO); final Map<String, String> params = new HashMap<String, String>(1); params.put(HttpConstants.Q, GoogleBookSearchKey.ISBN + isbn); final Map<String, String> headers = new HashMap<String, String>(1); headers.put(HttpConstants.KEY, mGoogleBooksApiKey); request.setParams(params); request.setHeaders(headers); addRequestToQueue(request, true, R.string.unable_to_fetch_book_info, false); } /** * Fetches the book info from server based on the Book ID. This is dependent on the service used * to fetch the book info * * @param bookId The unique ID of the book to get info for */ private void getBookInfoById(final String bookId, final String bookName) { final BlRequest request = new BlRequest(Method.GET, HttpConstants.getGoogleBooksUrl() + ApiEndpoints.VOLUMES, null, mVolleyCallbacks); request.setRequestId(RequestId.GOOGLEBOOKS_SHOW_BOOK); final Map<String, String> params = new HashMap<String, String>(1); params.put(HttpConstants.Q, GoogleBookSearchKey.ID + bookId + "+" + GoogleBookSearchKey.INTITLE + bookName); final Map<String, String> headers = new HashMap<String, String>(1); headers.put(HttpConstants.KEY, mGoogleBooksApiKey); request.setParams(params); request.setHeaders(headers); addRequestToQueue(request, false, 0, false); } /** * Updates the barter types checkboxes * * @param barterTypes A list of barter types chosen for the book */ private void setCheckBoxesForBarterTypes(final List<String> barterTypes) { if (barterTypes != null) { for (final CheckBox checkBox : mBarterTypeCheckBoxes) { if (barterTypes.contains(checkBox.getTag(R.string.tag_barter_type))) { checkBox.setChecked(true); } else { checkBox.setChecked(false); } } } } /** * Add the book to the server * * @param locationObject The location at which to create the book, if <code>null</code>, uses * the user's preferred location */ private void createBookOnServer(final JSONObject locationObject) { try { final JSONObject requestObject = new JSONObject(); final JSONObject bookJson = new JSONObject(); bookJson.put(HttpConstants.TITLE, mTitleEditText.getText().toString()); bookJson.put(HttpConstants.AUTHOR, mAuthorEditText.getText().toString()); bookJson.put(HttpConstants.DESCRIPTION, mDescriptionEditText.getText().toString()); if (!mSellPriceEditText.getText().toString().equals("")) { bookJson.put(HttpConstants.VALUE, mSellPriceEditText.getText().toString()); } bookJson.put(HttpConstants.PUBLICATION_YEAR, mPublicationYear); if (mIsbnEditText.getText().toString().length() == 13) { bookJson.put(HttpConstants.ISBN_13, mIsbnEditText.getText().toString()); } else if (mIsbnEditText.getText().toString().length() == 10) { bookJson.put(HttpConstants.ISBN_10, mIsbnEditText.getText().toString()); } bookJson.put(HttpConstants.TAG_NAMES, getBarterTagsArray()); bookJson.put(HttpConstants.EXT_IMAGE_URL, mImage_Url); if (locationObject != null) { bookJson.put(HttpConstants.LOCATION, locationObject); } requestObject.put(HttpConstants.BOOK, bookJson); final BlRequest createBookRequest = new BlRequest(Method.POST, HttpConstants.getApiBaseUrl() + ApiEndpoints.BOOKS, requestObject.toString(), mVolleyCallbacks); createBookRequest.setRequestId(RequestId.CREATE_BOOK); addRequestToQueue(createBookRequest, true, 0, true); } catch (final JSONException e) { e.printStackTrace(); } } @Override public void onActivityResult(final int requestCode, final int resultCode, final Intent data) { if (requestCode == AppConstants.RequestCodes.LOGIN_TO_ADD_BOOK) { if (resultCode == Activity.RESULT_OK) { checkAndFinishBookSubmitTask(); } } else { super.onActivityResult(requestCode, resultCode, data); } } /** * Updates the book to the server * * @param locationObject The location at which to create the book, if <code>null</code>, uses * the user's preferred location */ private void updateBookOnServer(final JSONObject locationObject) { try { final JSONObject requestObject = new JSONObject(); final JSONObject bookJson = new JSONObject(); bookJson.put(HttpConstants.TITLE, mTitleEditText.getText().toString()); bookJson.put(HttpConstants.AUTHOR, mAuthorEditText.getText().toString()); bookJson.put(HttpConstants.DESCRIPTION, mDescriptionEditText.getText().toString()); if (!mSellPriceEditText.getText().toString().equals("")) { bookJson.put(HttpConstants.VALUE, mSellPriceEditText.getText().toString()); } bookJson.put(HttpConstants.PUBLICATION_YEAR, mPublicationYear); if (mIsbnEditText.getText().toString().length() == 13) { bookJson.put(HttpConstants.ISBN_13, mIsbnEditText.getText().toString()); } else if (mIsbnEditText.getText().toString().length() == 10) { bookJson.put(HttpConstants.ISBN_10, mIsbnEditText.getText().toString()); } bookJson.put(HttpConstants.TAG_NAMES, getBarterTagsArray()); bookJson.put(HttpConstants.EXT_IMAGE_URL, mImage_Url); if (locationObject != null) { bookJson.put(HttpConstants.LOCATION, locationObject); } requestObject.put(HttpConstants.BOOK, bookJson); requestObject.put(HttpConstants.ID, mId); final BlRequest updateBookRequest = new BlRequest(Method.PUT, HttpConstants.getApiBaseUrl() + ApiEndpoints.BOOKS, requestObject.toString(), mVolleyCallbacks); updateBookRequest.setRequestId(RequestId.UPDATE_BOOK); addRequestToQueue(updateBookRequest, true, 0, true); } catch (final JSONException e) { e.printStackTrace(); } } /** * Build the tags array for books * * @return A {@link JSONArray} representing the barter tags */ private JSONArray getBarterTagsArray() { final JSONArray tagNamesArray = new JSONArray(); for (CheckBox checkBox : mBarterTypeCheckBoxes) { if (checkBox.isChecked()) { tagNamesArray.put(checkBox.getTag(R.string.tag_barter_type)); } } return tagNamesArray; } /** * Validates the current input. Sets errors for the text fields if there are any errors * * @return <code>true</code> if there are no errors, <code>fhalse</code> otherwise */ private boolean isInputValid() { boolean isValid = true; final String title = mTitleEditText.getText().toString(); final String isbn = mIsbnEditText.getText().toString(); isValid &= !TextUtils.isEmpty(title); if (!isValid) { mTitleEditText.setError(getString(R.string.error_enter_title)); } // Validation for at least one barter type set if (isValid) { // Flag to check if at least one of the barter checkboxes is checked boolean anyOneChecked = false; for (final CheckBox checkBox : mBarterTypeCheckBoxes) { anyOneChecked |= checkBox.isChecked(); } isValid &= anyOneChecked; if (!isValid) { showCrouton(R.string.select_a_barter_type, AlertStyle.ALERT); } } if (!TextUtils.isEmpty(isbn)) { isValid &= isNumeric(isbn); if (!((isbn.length() == 13) || (isbn.length() == 10))) { isValid = false; } } return isValid; } @Override public void onSuccess(final int requestId, final IBlRequestContract request, final ResponseInfo response) { switch (requestId) { case RequestId.GET_BOOK_INFO: { mTitleEditText.setTextWithFilter(response.responseBundle.getString(HttpConstants.TITLE), false); mDescriptionEditText.setText(response.responseBundle.getString(HttpConstants.DESCRIPTION)); mAuthorEditText.setText(response.responseBundle.getString(HttpConstants.AUTHOR)); mPublicationYear = response.responseBundle.getString(HttpConstants.PUBLICATION_YEAR); if (response.responseBundle.containsKey(HttpConstants.ISBN_13)) { mIsbnEditText.setText(response.responseBundle.getString(HttpConstants.ISBN_13)); } else if (response.responseBundle.containsKey(HttpConstants.ISBN_10)) { mIsbnEditText.setText(response.responseBundle.getString(HttpConstants.ISBN_10)); } mImage_Url = response.responseBundle.getString(HttpConstants.IMAGE_URL); Logger.d(TAG, "image url %s", mImage_Url); break; } case RequestId.GOOGLEBOOKS_SHOW_BOOK: { mTitleEditText.setTextWithFilter(response.responseBundle.getString(HttpConstants.TITLE), false); mDescriptionEditText.setText(response.responseBundle.getString(HttpConstants.DESCRIPTION)); mAuthorEditText.setText(response.responseBundle.getString(HttpConstants.AUTHOR)); mPublicationYear = response.responseBundle.getString(HttpConstants.PUBLICATION_YEAR); if (response.responseBundle.containsKey(HttpConstants.ISBN_13)) { mIsbnEditText.setText(response.responseBundle.getString(HttpConstants.ISBN_13)); } else if (response.responseBundle.containsKey(HttpConstants.ISBN_10)) { mIsbnEditText.setText(response.responseBundle.getString(HttpConstants.ISBN_10)); } mImage_Url = response.responseBundle.getString(HttpConstants.IMAGE_URL); Logger.d(TAG, "image url %s", mImage_Url); break; } case RequestId.CREATE_BOOK: { final String bookId = response.responseBundle.getString(HttpConstants.ID); loadBookDetails(QueryTokens.LOAD_BOOK_DETAIL_FOR_OPEN, bookId); break; } case RequestId.UPDATE_BOOK: { loadBookDetails(QueryTokens.LOAD_BOOK_DETAIL_FOR_OPEN, mId); break; } case RequestId.BOOK_SUGGESTIONS: { final Suggestion[] fetchedSuggestions = (Suggestion[]) response.responseBundle .getParcelableArray(HttpConstants.RESULTS); if ((fetchedSuggestions != null) && (fetchedSuggestions.length > 0)) { mTitleEditText.onSuggestionsFetched((String) request.getExtras().get(Keys.SEARCH), fetchedSuggestions, true); } break; } /* * This will happen in the case where the user has newly signed in * using email/passowrd and doesn't have a first name added yet. The * request is placed into the queue from * AbstractBarterLiFragment#onDialogClick() */ case RequestId.SAVE_USER_PROFILE: { final Bundle userInfo = response.responseBundle; Utils.updateUserInfoFromBundle(userInfo, true); createBookOnServer(null); break; } } } @Override public void onBadRequestError(final int requestId, final IBlRequestContract request, final int errorCode, final String errorMessage, final Bundle errorResponseBundle) { if (requestId == RequestId.GET_BOOK_INFO) { showCrouton(R.string.unable_to_fetch_book_info, AlertStyle.ERROR); } else if (requestId == RequestId.CREATE_BOOK) { showCrouton(R.string.unable_to_create_book, AlertStyle.ERROR); } } @Override public void onOtherError(int requestId, IBlRequestContract request, int errorCode) { if (requestId == RequestId.GET_BOOK_INFO) { showCrouton(R.string.unable_to_fetch_book_info, AlertStyle.ERROR); } else if (requestId == RequestId.CREATE_BOOK) { showCrouton(R.string.unable_to_create_book, AlertStyle.ERROR); } } @Override public void onPostExecute(IBlRequestContract request) { super.onPostExecute(request); final int requestId = request.getRequestId(); if (requestId == RequestId.CREATE_BOOK || requestId == RequestId.UPDATE_BOOK) { mIsUpoading = false; } } @Override public void onInsertComplete(final int token, final Object cookie, final long insertRowId) { } @Override public void onDeleteComplete(final int token, final Object cookie, final int deleteCount) { } @Override public void onUpdateComplete(final int token, final Object cookie, final int updateCount) { } @Override public void onQueryComplete(final int token, final Object cookie, final Cursor cursor) { if (token == QueryTokens.LOAD_BOOK_DETAIL_FOR_EDIT) { if (cursor.moveToFirst()) { /* Force a crash if trying to edit someone else's book. This should not happen in production */ final String userId = cursor.getString(cursor.getColumnIndex(DatabaseColumns.USER_ID)); if (!userId.equals(AppConstants.UserInfo.INSTANCE.getId())) { throw new RuntimeException("Trying to edit someone else's book!"); } mIsbnEditText.setText(cursor.getString(cursor.getColumnIndex(DatabaseColumns.ISBN_10))); mTitleEditText.setTextWithFilter(cursor.getString(cursor.getColumnIndex(DatabaseColumns.TITLE)), false); mAuthorEditText.setText(cursor.getString(cursor.getColumnIndex(DatabaseColumns.AUTHOR))); mDescriptionEditText.setText(cursor.getString(cursor.getColumnIndex(DatabaseColumns.DESCRIPTION))); mPublicationYear = cursor.getString(cursor.getColumnIndex(DatabaseColumns.PUBLICATION_YEAR)); mImage_Url = cursor.getString(cursor.getColumnIndex(DatabaseColumns.IMAGE_URL)); final String value = cursor.getString(cursor.getColumnIndex(DatabaseColumns.VALUE)); if (!TextUtils.isEmpty(value)) { mSellPriceEditText.setVisibility(View.VISIBLE); mSellPriceEditText.setText(value); } final String barterType = cursor.getString(cursor.getColumnIndex(DatabaseColumns.BARTER_TYPE)); if (!TextUtils.isEmpty(barterType)) { setBarterCheckboxes(barterType); } } cursor.close(); } else if (token == QueryTokens.LOAD_BOOK_DETAIL_FOR_OPEN) { if (cursor.moveToFirst()) { final Bundle showBooksArgs = Utils.cursorToBundle(cursor); final Intent resultIntent = new Intent(); resultIntent.putExtras(showBooksArgs); getActivity().setResult(ActionBarActivity.RESULT_OK, resultIntent); getActivity().finish(); } } } /** * Checks the supported barter type of the book and updates the checkboxes * * @param barterType The barter types supported by the book */ private void setBarterCheckboxes(final String barterType) { final String[] barterTypes = barterType.split(AppConstants.BARTER_TYPE_SEPARATOR); for (final String token : barterTypes) { for (final CheckBox eachCheckBox : mBarterTypeCheckBoxes) { if (eachCheckBox.getTag(R.string.tag_barter_type).equals(token)) { eachCheckBox.setChecked(true); } } } } /** * Function to see if a string is numeric */ private boolean isNumeric(final String str) { return str.matches("\\d+"); } @Override public void performNetworkQuery(final NetworkedAutoCompleteTextView textView, final String query) { if (textView.getId() == R.id.edit_text_title) { Logger.v(TAG, "Perform network query %s", query); final BlRequest request = new BlRequest(Method.GET, HttpConstants.getGoogleBooksUrl() + ApiEndpoints.VOLUMES, null, mVolleyCallbacks); request.setRequestId(RequestId.BOOK_SUGGESTIONS); final Map<String, String> params = new HashMap<String, String>(1); params.put(HttpConstants.Q, GoogleBookSearchKey.INTITLE + query); final Map<String, String> headers = new HashMap<String, String>(1); headers.put(HttpConstants.KEY, mGoogleBooksApiKey); request.setParams(params); request.setHeaders(headers); addRequestToQueue(request, false, 0, false); } } @Override public void onSuggestionClicked(final NetworkedAutoCompleteTextView textView, final Suggestion suggestion) { if (textView.getId() == R.id.edit_text_title) { Logger.v(TAG, "On Suggestion Clicked %s", suggestion); getBookInfoById(suggestion.id, suggestion.name); hideKeyBoard(textView); } } @Override public void onCheckedChanged(final CompoundButton buttonView, final boolean isChecked) { if (isChecked) { mSellPriceEditText.setVisibility(View.VISIBLE); } else { mSellPriceEditText.setVisibility(View.GONE); } } @Override protected String getAnalyticsScreenName() { if (mEditMode) { return Screens.EDIT_BOOK; } else { return Screens.ADD_BOOK; } } }