Java tutorial
/* * Copyright 2016 Promtech. All rights reserved. * * 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 ru.gkpromtech.exhibition; import android.app.Activity; import android.content.SharedPreferences; import android.content.res.Configuration; import android.os.Bundle; import android.preference.PreferenceManager; import android.support.v4.app.Fragment; import android.support.v4.view.GravityCompat; 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.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.LinearLayout; import android.widget.ListView; public class NavigationDrawerFragment extends Fragment { private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position"; private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned"; private NavigationDrawerCallbacks mCallbacks; private ActionBarDrawerToggle mDrawerToggle; private DrawerLayout mDrawerLayout; private ListView mDrawerListView; private View mFragmentContainerView; private int mCurrentSelectedPosition = 0; private boolean mFromSavedInstanceState; private boolean mUserLearnedDrawer; public NavigationDrawerFragment() { } @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. SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity()); mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false); int pos = getActivity().getIntent().getIntExtra("position", -1); if (pos != -1) mCurrentSelectedPosition = pos; if (savedInstanceState != null) { mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION); mFromSavedInstanceState = true; } // Select either the default item (0) or the last selected item. selectItem(mCurrentSelectedPosition, false); } @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, Bundle savedInstanceState) { LinearLayout layout = (LinearLayout) inflater.inflate(R.layout.fragment_navigation_drawer, container, false); mDrawerListView = (ListView) layout.findViewById(R.id.listNav); mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { selectItem(position, true); } }); String[] items = new String[Navigation.ITEMS.length]; for (int i = 0, l = Navigation.ITEMS.length; i < l; ++i) { items[i] = getString(Navigation.ITEMS[i].getTitle()); } mDrawerListView.setAdapter(new ArrayAdapter<>(getActionBar().getThemedContext(), R.layout.drawer_list_item, android.R.id.text1, items)); mDrawerListView.setItemChecked(mCurrentSelectedPosition, true); return layout; } public boolean isDrawerOpen() { return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView); } /** * 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) { mFragmentContainerView = getActivity().findViewById(fragmentId); mDrawerLayout = drawerLayout; // set a custom shadow that overlays the main content when the drawer opens mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); // set up the drawer's list view with items and click listener 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. mDrawerToggle = new ActionBarDrawerToggle(getActivity(), /* host Activity */ mDrawerLayout, /* 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().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu() } @Override public void onDrawerOpened(View drawerView) { super.onDrawerOpened(drawerView); if (!isAdded()) { return; } if (!mUserLearnedDrawer) { // The user manually opened the drawer; store this flag to prevent auto-showing // the navigation drawer automatically in the future. mUserLearnedDrawer = true; SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity()); sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply(); } getActivity().supportInvalidateOptionsMenu(); // 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 (!mUserLearnedDrawer && !mFromSavedInstanceState) { mDrawerLayout.openDrawer(mFragmentContainerView); mUserLearnedDrawer = true; SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity()); sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply(); } // Defer code dependent on restoration of previous instance state. mDrawerLayout.post(new Runnable() { @Override public void run() { mDrawerToggle.syncState(); } }); mDrawerLayout.setDrawerListener(mDrawerToggle); } private void selectItem(int position, boolean isUserAction) { mCurrentSelectedPosition = position; if (mDrawerListView != null) { mDrawerListView.setItemChecked(position, true); } if (mDrawerLayout != null) { mDrawerLayout.closeDrawer(mFragmentContainerView); } if (mCallbacks != null) { if (isUserAction) { mCallbacks.onNavigationDrawerItemSelected(position); } else { mCallbacks.onNavigationDrawerShowView(position); } } } @Override public void onAttach(Activity activity) { super.onAttach(activity); try { mCallbacks = (NavigationDrawerCallbacks) activity; } catch (ClassCastException e) { throw new ClassCastException("Activity must implement NavigationDrawerCallbacks."); } } @Override public void onDetach() { super.onDetach(); mCallbacks = null; } @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition); } @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); // Forward the new configuration the drawer toggle component. if (mDrawerToggle != null) mDrawerToggle.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 (mDrawerLayout != null && isDrawerOpen()) { inflater.inflate(R.menu.global, menu); showGlobalContextActionBar(); } super.onCreateOptionsMenu(menu, inflater); } @Override public boolean onOptionsItemSelected(MenuItem item) { //noinspection SimplifiableIfStatement if (mDrawerToggle != null && mDrawerToggle.onOptionsItemSelected(item)) { return true; } return 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() { 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); void onNavigationDrawerShowView(int position); } }