I'm trying to implement sliding tab layout using android material design. But it gives me NullPointerException. Here is my code so far:
MainActivity.java
public class MainActivity extends ActionBarActivity { private Toolbar toolbar; private ViewPager pager; private SlidingTabLayout nLayout; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main_appbar); toolbar = (Toolbar) findViewById(R.id.app_bar); setSupportActionBar(toolbar); getSupportActionBar().setDisplayShowHomeEnabled(true); NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment) getSupportFragmentManager().findFragmentById(R.id.navigation_drawer_fragment); drawerFragment.setUp(R.id.navigation_drawer_fragment, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar); pager = (ViewPager) findViewById(R.id.pager); pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager())); nLayout = (SlidingTabLayout) findViewById(R.id.tabs); nLayout.setViewPager(pager); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } if (id == R.id.navigate) { startActivity(new Intent(this, SubActivity.class)); } return super.onOptionsItemSelected(item); } class MyPagerAdapter extends FragmentPagerAdapter { String tabs[]; public MyPagerAdapter(FragmentManager fm) { super(fm); tabs = getResources().getStringArray(R.array.tabs); } @Override public Fragment getItem(int position) { MyFragment myFragment = MyFragment.getInstance(position); return myFragment; } @Override public CharSequence getPageTitle(int position) { return tabs[position]; } @Override public int getCount() { return 3; } } public static class MyFragment extends Fragment { private TextView textView; public static MyFragment getInstance(int position) { MyFragment myFragment = new MyFragment(); Bundle args = new Bundle(); args.putInt("position", position); myFragment.setArguments(args); return myFragment; } @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View layout = inflater.inflate(R.layout.fragment_my, container, false); textView = (TextView) layout.findViewById(R.id.position); Bundle bundle = getArguments(); if (bundle != null) { textView.setText("The page selected is " + bundle.getInt("position")); } return layout; } } } activity_main.xml
<LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="carsaleapp.shanaka.com.carsaleapp.MainActivity"> <include android:id="@+id/app_bar" layout="@layout/app_bar" /> <app.shanaka.tabs.SlidingTabLayout android:id="@+id/tabs" android:layout_width="match_parent" android:layout_height="wrap_content" /> <android.support.v4.view.ViewPager android:id="@+id/pager" android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" /> </LinearLayout> This is the error I got after run my application:
They keep on saying that the pager object is null. But for me I have set it correctly.
pager = (ViewPager) findViewById(R.id.pager);