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POimplementing tabs with simple views and fragments
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  1. POimplementing tabs with simple views and fragments
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    copied!<p>After one week struggle with common ways of implementing tabs like TabActivity and fragments and viewPager I failed to get a instance of Activities or fragments of tabs and couldn't find a way to solve the issue. So I decided to implement it in a different way. First I make a tabWidget with a simple button. In android developer website I find out a way to replace fragment in runtime. so the only thing remains is that how to get access to tab fragments to invoke methods from my FragmentActivity. </p> <p>here is my FragmentActivity using pageViewer. I get nullpointer when I want to get fragment object of my tab in <code>setup()</code> method:</p> <pre><code>public class MainActivity extends FragmentActivity implements OnTabChangeListener, OnPageChangeListener { private TabHost mTabHost; private ViewPager mViewPager; private HashMap&lt;String, TabInfo&gt; mapTabInfo = new HashMap&lt;String, MainActivity.TabInfo&gt;(); private PagerAdapter mPagerAdapter; private TabInfo mLastTab = null; private class TabInfo { private String tag; private Class clss; private Bundle args; private Fragment fragment; TabInfo(String tag, Class clazz, Bundle args) { this.tag = tag; this.clss = clazz; this.args = args; } } class TabFactory implements TabContentFactory { private final Context mContext; /** * @param context */ public TabFactory(Context context) { mContext = context; } /** * (non-Javadoc) * * @see android.widget.TabHost.TabContentFactory#createTabContent(java.lang.String) */ public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth(0); v.setMinimumHeight(0); return v; } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); this.requestWindowFeature(Window.FEATURE_NO_TITLE); Log.d("checking", "setup tabs..."); setContentView(R.layout.activity_main); // // initialiseTabHost(savedInstanceState); if (savedInstanceState != null) { mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab")); } intialiseViewPager(); // // setup(); // /// } protected void onSaveInstanceState(Bundle outState) { outState.putString("tab", mTabHost.getCurrentTabTag()); // save the tab // selected super.onSaveInstanceState(outState); } private void intialiseViewPager() { List&lt;Fragment&gt; fragments = new Vector&lt;Fragment&gt;(); fragments .add(Fragment.instantiate(this, CoachFragment.class.getName())); fragments .add(Fragment.instantiate(this, LogingFragment.class.getName())); fragments.add(Fragment.instantiate(this, HistoryFragment.class.getName())); this.mPagerAdapter = new PagerAdapter( super.getSupportFragmentManager(), fragments); // this.mViewPager = (ViewPager) super.findViewById(R.id.viewpager); this.mViewPager.setAdapter(this.mPagerAdapter); this.mViewPager.setOnPageChangeListener(this); mViewPager.setOffscreenPageLimit(1000000); } private void initialiseTabHost(Bundle args) { mTabHost = (TabHost) findViewById(android.R.id.tabhost); mTabHost.setup(); mTabHost.getTabWidget().setDividerDrawable(R.drawable.tab_divider); TabInfo tabInfo = null; View tabView1 = createTabView(this, coach"); MainActivity.AddTab(this, this.mTabHost, this.mTabHost .newTabSpec("Tab1").setIndicator(tabView1), (tabInfo = new TabInfo("Tab1", CoachFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); View tabView2 = createTabView(this, logbook"); MainActivity.AddTab(this, this.mTabHost, this.mTabHost .newTabSpec("Tab2").setIndicator(tabView2), (tabInfo = new TabInfo("Tab2", LogingFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); View tabView3 = createTabView(this, "history"); MainActivity.AddTab(this, this.mTabHost, this.mTabHost .newTabSpec("Tab3").setIndicator(tabView3), (tabInfo = new TabInfo("Tab3", HistoryFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); mTabHost.setOnTabChangedListener(this); } private static void AddTab(MainActivity activity, TabHost tabHost, TabHost.TabSpec tabSpec, TabInfo tabInfo) { // Attach a Tab view factory to the spec tabSpec.setContent(activity.new TabFactory(activity)); tabHost.addTab(tabSpec); } public void setup() { .... CoachFragment fragment=(CoachFragment) mPagerAdapter.getRegisteredFragment(mViewPager.getCurrentItem()); fragment.setTempView(R.id.welcome); fragment.animate(); .... } public void onTabChanged(String tag) { // TabInfo newTab = this.mapTabInfo.get(tag); int pos = this.mTabHost.getCurrentTab(); this.mViewPager.setCurrentItem(pos); } private static View createTabView(final Context context, final String text) { View view = LayoutInflater.from(context) .inflate(R.layout.tabs_bg, null); TextView tv = (TextView) view.findViewById(R.id.tabsText); tv.setText(text); return view; } @Override public void onPageScrollStateChanged(int arg0) { // TODO Auto-generated method stub } @Override public void onPageScrolled(int arg0, float arg1, int arg2) { // TODO Auto-generated method stub } @Override public void onPageSelected(int position) { // TODO Auto-generated method stub this.mTabHost.setCurrentTab(position); } </code></pre> <p>}</p> <p>my pageAdapter:</p> <pre><code>public class PagerAdapter extends FragmentPagerAdapter { private List&lt;Fragment&gt; fragments; private HashMap&lt;Integer, Fragment&gt; registeredFragments=new HashMap&lt;Integer, Fragment&gt;(); /** * @param fm * @param fragments */ public PagerAdapter(FragmentManager fm, List&lt;Fragment&gt; fragments) { super(fm); this.fragments = fragments; } /* (non-Javadoc) * @see android.support.v4.app.FragmentPagerAdapter#getItem(int) */ @Override public Fragment getItem(int position) { return this.fragments.get(position); } @Override public Object instantiateItem(ViewGroup container, int position) { Fragment fragment = (Fragment) super.instantiateItem(container, position); registeredFragments.put(position, fragment); return fragment; } @Override public void destroyItem(ViewGroup container, int position, Object object) { registeredFragments.remove(position); super.destroyItem(container, position, object); } public Fragment getRegisteredFragment(int position) { return registeredFragments.get(position); } /* (non-Javadoc) * @see android.support.v4.view.PagerAdapter#getCount() */ @Override public int getCount() { return this.fragments.size(); } </code></pre> <p>}</p> <p>and my LogingFragment. the other 2 fragments are exactly the same one:</p> <pre><code>public class LogingFragment extends Fragment{ public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { if (container == null) { // We have different layouts, and in one of them this // fragment's containing frame doesn't exist. The fragment // may still be created from its saved state, but there is // no reason to try to create its view hierarchy because it // won't be displayed. Note this is not needed -- we could // just run the code below, where we would create and return // the view hierarchy; it would just never be used. return null; } return (LinearLayout)inflater.inflate(R.layout.coach_activity, container, false); } </code></pre> <p>}</p> <p>Every Thing works perfect and all looking and swiping works fine but in setup() method I get nullPointer. please help me with it.</p>
 

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