Java tutorial
package com.zzolta.android.gfrecipes.fragments; import android.app.Activity; import android.app.Fragment; import android.content.SharedPreferences; import android.content.res.Configuration; import android.os.Bundle; import android.preference.PreferenceManager; import android.support.v4.widget.DrawerLayout; import android.support.v7.app.ActionBar; import android.support.v7.app.ActionBarActivity; import android.support.v7.app.ActionBarDrawerToggle; import android.view.*; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import com.zzolta.android.gfrecipes.R; /* * Copyright (C) 2015 Zolta Szekely * * 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. */ public class NavigationDrawerFragment extends Fragment { /** * Remember the position of the selected item. */ private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position"; /** * Per the design guidelines, you should show the drawer on launch until the user manually * expands it. This shared preference tracks this. */ private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned"; /** * A pointer to the current callbacks instance (the Activity). */ private NavigationDrawerCallbacks navigationDrawerCallbacks; /** * Helper component that ties the action bar to the navigation drawer. */ private ActionBarDrawerToggle actionBarDrawerToggle; private DrawerLayout drawerLayout; private ListView drawerListView; private View fragmentContainerView; private int currentSelectedPosition; private boolean fromSavedInstanceState; private boolean userLearnedDrawer; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Read in the flag indicating whether or not the user has demonstrated awareness of the // drawer. See PREF_USER_LEARNED_DRAWER for details. final SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getActivity()); userLearnedDrawer = sharedPreferences.getBoolean(PREF_USER_LEARNED_DRAWER, false); if (savedInstanceState != null) { currentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION); fromSavedInstanceState = true; } // Select either the default item (0) or the last selected item. selectItem(currentSelectedPosition, savedInstanceState != null); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); // Indicate that this fragment would like to influence the set of actions in the action bar. setHasOptionsMenu(true); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, final Bundle savedInstanceState) { drawerListView = (ListView) inflater.inflate(R.layout.fragment_navigation_drawer, container, false); drawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { selectItem(position, false); } }); final String[] menuItems = { getString(R.string.recipe_of_the_day_menu), getString(R.string.search_menu), getString(R.string.my_recipes_menu), getString(R.string.feedback_menu) }; drawerListView.setAdapter(new ArrayAdapter<>(getActionBar().getThemedContext(), android.R.layout.simple_list_item_activated_1, android.R.id.text1, menuItems)); drawerListView.setItemChecked(currentSelectedPosition, true); return drawerListView; } public boolean isDrawerOpen() { return drawerLayout != null && drawerLayout.isDrawerOpen(fragmentContainerView); } /** * Users of this fragment must call this method to set up the navigation drawer interactions. * @param fragmentId The android:id of this fragment in its activity's layout. * @param drawerLayout The DrawerLayout containing this fragment's UI. */ public void setUp(int fragmentId, DrawerLayout drawerLayout) { fragmentContainerView = getActivity().findViewById(fragmentId); this.drawerLayout = drawerLayout; // set a custom shadow that overlays the main content when the drawer opens this.drawerLayout.setDrawerShadow(R.drawable.drawer_shadow, Gravity.START); // set up the drawer's list view with items and click listener final ActionBar actionBar = getActionBar(); actionBar.setDisplayHomeAsUpEnabled(true); actionBar.setHomeButtonEnabled(true); // ActionBarDrawerToggle ties together the the proper interactions // between the navigation drawer and the action bar app icon. actionBarDrawerToggle = new ActionBarDrawerToggle(getActivity(), /* host Activity */ NavigationDrawerFragment.this.drawerLayout, /* DrawerLayout object */ R.string.navigation_drawer_open, /* "open drawer" description for accessibility */ R.string.navigation_drawer_close /* "close drawer" description for accessibility */ ) { @Override public void onDrawerClosed(View drawerView) { super.onDrawerClosed(drawerView); if (!isAdded()) { return; } getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu() } @Override public void onDrawerOpened(View drawerView) { super.onDrawerOpened(drawerView); if (!isAdded()) { return; } if (!userLearnedDrawer) { // The user manually opened the drawer; store this flag to prevent auto-showing // the navigation drawer automatically in the future. userLearnedDrawer = true; final SharedPreferences sharedPreferences = PreferenceManager .getDefaultSharedPreferences(getActivity()); sharedPreferences.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply(); } getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu() } }; // If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer, // per the navigation drawer design guidelines. if (!userLearnedDrawer && !fromSavedInstanceState) { this.drawerLayout.openDrawer(fragmentContainerView); } // Defer code dependent on restoration of previous instance state. this.drawerLayout.post(new Runnable() { @Override public void run() { actionBarDrawerToggle.syncState(); } }); this.drawerLayout.setDrawerListener(actionBarDrawerToggle); } private void selectItem(int position, boolean fromSavedInstanceState) { currentSelectedPosition = position; if (drawerListView != null) { drawerListView.setItemChecked(position, true); } if (drawerLayout != null) { drawerLayout.closeDrawer(fragmentContainerView); } if (navigationDrawerCallbacks != null) { navigationDrawerCallbacks.onNavigationDrawerItemSelected(position, fromSavedInstanceState); } } @Override public void onAttach(Activity activity) { super.onAttach(activity); navigationDrawerCallbacks = (NavigationDrawerCallbacks) activity; } @Override public void onDetach() { super.onDetach(); navigationDrawerCallbacks = null; } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt(STATE_SELECTED_POSITION, currentSelectedPosition); } @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); // Forward the new configuration the drawer toggle component. actionBarDrawerToggle.onConfigurationChanged(newConfig); } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { // If the drawer is open, show the global app actions in the action bar. See also // showGlobalContextActionBar, which controls the top-left area of the action bar. if (drawerLayout != null && isDrawerOpen()) { inflater.inflate(R.menu.global, menu); showGlobalContextActionBar(); } super.onCreateOptionsMenu(menu, inflater); } @Override public boolean onOptionsItemSelected(MenuItem item) { return actionBarDrawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item); } /** * Per the navigation drawer design guidelines, updates the action bar to show the global app * 'context', rather than just what's in the current screen. */ private void showGlobalContextActionBar() { final ActionBar actionBar = getActionBar(); actionBar.setDisplayShowTitleEnabled(true); actionBar.setTitle(R.string.app_name); } private ActionBar getActionBar() { return ((ActionBarActivity) getActivity()).getSupportActionBar(); } /** * Callbacks interface that all activities using this fragment must implement. */ public interface NavigationDrawerCallbacks { /** * Called when an item in the navigation drawer is selected. */ void onNavigationDrawerItemSelected(int position, boolean fromSavedInstanceState); } }