title: Android Application keeps crashing
body: <p>I want to make an application which on login shows a "home" activity which has a navigation bar. I used android studios navigation drawer template and edited it to switch between fragments, but now the application is crashing on login. Any help on what am I doing wrong is appreciated.</p>
  
  <p>P.S. I am an amateur so I apologize for any stupid questions asked. </p>
  
  <pre><code>package zade.example.com.zade;
  
  import android.os.Bundle;
  import android.support.v4.app.Fragment;
  import android.support.v4.app.FragmentManager;
  import android.support.v4.widget.DrawerLayout;
  import android.support.v7.app.ActionBar;
  import android.support.v7.app.ActionBarActivity;
  import android.view.Menu;
  import android.view.MenuItem;
  
  
  public class Student_Home extends ActionBarActivity
          implements NavigationDrawerFragment.NavigationDrawerCallbacks {
  
      /**
       * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
       */
      private NavigationDrawerFragment mNavigationDrawerFragment;
  
      /**
       * Used to store the last screen title. For use in {@link #restoreActionBar()}.
       */
      private CharSequence mTitle;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_student__home);
  
          mNavigationDrawerFragment = (NavigationDrawerFragment)
                  getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
          mTitle = getTitle();
  
          // Set up the drawer.
          mNavigationDrawerFragment.setUp(
                  R.id.navigation_drawer,
                  (DrawerLayout) findViewById(R.id.drawer_layout));
      }
  
      @Override
      public void onNavigationDrawerItemSelected(int position) {
  
          Fragment objfragment = null;
  
          switch (position) {
              case 1:
                  objfragment = new MyFragment1();
                  break;
              case 2:
                  objfragment = new MyFragment2();
                  break;
              case 3:
                  objfragment = new MyFragment3();
                  break;
          }
          // update the main content by replacing fragments
          FragmentManager fragmentManager = getSupportFragmentManager();
          fragmentManager.beginTransaction()
                  .replace(R.id.container, objfragment)
                  .commit();
      }
  
      public void onSectionAttached(int number) {
          switch (number) {
              case 1:
                  mTitle = getString(R.string.title_section1);
                  break;
              case 2:
                  mTitle = getString(R.string.title_section2);
                  break;
              case 3:
                  mTitle = getString(R.string.title_section3);
                  break;
          }
      }
  
      public void restoreActionBar() {
          ActionBar actionBar = getSupportActionBar();
          actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
          actionBar.setDisplayShowTitleEnabled(true);
          actionBar.setTitle(mTitle);
      }
  
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          if (!mNavigationDrawerFragment.isDrawerOpen()) {
              // Only show items in the action bar relevant to this screen
              // if the drawer is not showing. Otherwise, let the drawer
              // decide what to show in the action bar.
              getMenuInflater().inflate(R.menu.student__home, menu);
              restoreActionBar();
              return true;
          }
          return super.onCreateOptionsMenu(menu);
      }
  
      @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;
          }
  
          return super.onOptionsItemSelected(item);
      }
  
  }
  </code></pre>
  
  <p>The logcat is :</p>
  
  <pre><code> E/AndroidRuntime﹕ FATAL EXCEPTION: main
          Process: zade.example.com.zade, PID: 2052
          java.lang.RuntimeException: Unable to start activity ComponentInfo{zade.example.com.zade/zade.example.com.zade.Student_Home}: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
                  at android.app.ActivityThread.access$800(ActivityThread.java:144)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5221)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
           Caused by: android.view.InflateException: Binary XML file line #19: Error inflating class fragment
                  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:763)
                  at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
                  at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
                  at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
                  at zade.example.com.zade.Student_Home.onCreate(Student_Home.java:29)
                  at android.app.Activity.performCreate(Activity.java:5933)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
                  at android.app.ActivityThread.access$800(ActivityThread.java:144)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5221)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
           Caused by: java.lang.NullPointerException: Attempt to write to field 'android.support.v4.app.FragmentManagerImpl android.support.v4.app.Fragment.mFragmentManager' on a null object reference
                  at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:416)
                  at android.support.v4.app.BackStackRecord.replace(BackStackRecord.java:451)
                  at android.support.v4.app.BackStackRecord.replace(BackStackRecord.java:443)
                  at zade.example.com.zade.Student_Home.onNavigationDrawerItemSelected(Student_Home.java:60)
                  at zade.example.com.zade.NavigationDrawerFragment.selectItem(NavigationDrawerFragment.java:200)
                  at zade.example.com.zade.NavigationDrawerFragment.onCreate(NavigationDrawerFragment.java:79)
                  at android.support.v4.app.Fragment.performCreate(Fragment.java:1763)
                  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:913)
                  at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
                  at android.support.v4.app.FragmentManagerImpl.addFragment(FragmentManager.java:1206)
                  at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:2159)
                  at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:297)
                  at android.support.v7.app.ActionBarActivity.onCreateView(ActionBarActivity.java:547)
                  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
                  at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
                  at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
                  at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
                  at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
                  at zade.example.com.zade.Student_Home.onCreate(Student_Home.java:29)
                  at android.app.Activity.performCreate(Activity.java:5933)
                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
                  at android.app.ActivityThread.access$800(ActivityThread.java:144)
                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
                  at android.os.Handler.dispatchMessage(Handler.java:102)
                  at android.os.Looper.loop(Looper.java:135)
                  at android.app.ActivityThread.main(ActivityThread.java:5221)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at java.lang.reflect.Method.invoke(Method.java:372)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
  </code></pre>