Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * 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 pro.dbro.iburn_2012; import android.content.Context; import android.content.SharedPreferences; import android.content.res.Resources; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.view.Display; import android.view.View; import android.view.ViewGroup; import android.widget.TabHost; import android.widget.TabWidget; import java.util.ArrayList; import pro.dbro.iburn_2012.data.DataUtils; /** * Demonstrates combining a TabHost with a ViewPager to implement a tab UI * that switches between tabs and also allows the user to perform horizontal * flicks to move between the tabs. */ public class FragmentTabsPager extends FragmentActivity { TabHost mTabHost; public static ViewPager mViewPager; TabsAdapter mTabsAdapter; public static iBurnApplication app; public static int display_width = -1; Resources res; private SharedPreferences prefs; private SharedPreferences.Editor editor; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Display display = getWindowManager().getDefaultDisplay(); display_width = display.getWidth(); setContentView(R.layout.fragment_tabs_pager); app = (iBurnApplication) getApplicationContext(); mTabHost = (TabHost) findViewById(android.R.id.tabhost); mTabHost.setup(); mViewPager = (ViewPager) findViewById(R.id.pager); mTabsAdapter = new TabsAdapter(this, mTabHost, mViewPager); mTabsAdapter.addTab(mTabHost.newTabSpec("map").setIndicator("Map"), OpenStreetMapFragment.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("art").setIndicator("Art"), ArtFragment.CursorLoaderListFragment.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("camps").setIndicator("Camps"), CampFragment.CursorLoaderListFragment.class, null); mTabsAdapter.addTab(mTabHost.newTabSpec("events").setIndicator("Events"), EventFragment.CursorLoaderListFragment.class, null); if (savedInstanceState != null) { mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab")); } res = getResources(); prefs = getSharedPreferences("PREFS", 0); editor = prefs.edit(); /* * Uncomment this to populate initial data from JSON * If you do this, comment out DBWrapper.getWritableDatabase() * to avoid also copying bundled pre-populated database if(prefs.getBoolean("dbReady", false)){ new DataUtils.PopulateDBFromJsonTask().execute(); } */ } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putString("tab", mTabHost.getCurrentTabTag()); } /** * This is a helper class that implements the management of tabs and all * details of connecting a ViewPager with associated TabHost. It relies on a * trick. Normally a tab host has a simple API for supplying a View or * Intent that each tab will show. This is not sufficient for switching * between pages. So instead we make the content part of the tab host * 0dp high (it is not shown) and the TabsAdapter supplies its own dummy * view to show as the tab content. It listens to changes in tabs, and takes * care of switch to the correct paged in the ViewPager whenever the selected * tab changes. */ public static class TabsAdapter extends FragmentPagerAdapter implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener { private final Context mContext; private final TabHost mTabHost; private final ViewPager mViewPager; private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>(); static final class TabInfo { private final String tag; private final Class<?> clss; private final Bundle args; TabInfo(String _tag, Class<?> _class, Bundle _args) { tag = _tag; clss = _class; args = _args; } } static class DummyTabFactory implements TabHost.TabContentFactory { private final Context mContext; public DummyTabFactory(Context context) { mContext = context; } @Override public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth(0); v.setMinimumHeight(0); return v; } } public TabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) { super(activity.getSupportFragmentManager()); mContext = activity; mTabHost = tabHost; mViewPager = pager; mTabHost.setOnTabChangedListener(this); mViewPager.setAdapter(this); mViewPager.setOnPageChangeListener(this); } public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args) { tabSpec.setContent(new DummyTabFactory(mContext)); String tag = tabSpec.getTag(); TabInfo info = new TabInfo(tag, clss, args); mTabs.add(info); mTabHost.addTab(tabSpec); notifyDataSetChanged(); } @Override public int getCount() { return mTabs.size(); } @Override public Fragment getItem(int position) { TabInfo info = mTabs.get(position); return Fragment.instantiate(mContext, info.clss.getName(), info.args); } @Override public void onTabChanged(String tabId) { int position = mTabHost.getCurrentTab(); mViewPager.setCurrentItem(position); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { // Unfortunately when TabHost changes the current tab, it kindly // also takes care of putting focus on it when not in touch mode. // The jerk. // This hack tries to prevent this from pulling focus out of our // ViewPager. TabWidget widget = mTabHost.getTabWidget(); int oldFocusability = widget.getDescendantFocusability(); widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS); mTabHost.setCurrentTab(position); widget.setDescendantFocusability(oldFocusability); } @Override public void onPageScrollStateChanged(int state) { } } }