title: getApplicationContext() returns null, but works in other activities
body: <p>I'm using a SQLite database and whenever I call it, I need to pass the context to it. I usually do this using getApplicationContext() which works in other activities. 
  In my current class it just returns null. Help!</p>
  
  <pre><code>04-06 16:46:19.523: E/AndroidRuntime(4279): Process: com.example.schoolandrevisiontimetable, PID: 4279
  04-06 16:46:19.523: E/AndroidRuntime(4279): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.schoolandrevisiontimetable/com.example.schoolandrevisiontimetable.Input_slessontime}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread.access$800(ActivityThread.java:148)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.os.Handler.dispatchMessage(Handler.java:102)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.os.Looper.loop(Looper.java:135)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread.main(ActivityThread.java:5312)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at java.lang.reflect.Method.invoke(Native Method)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at java.lang.reflect.Method.invoke(Method.java:372)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696)
  04-06 16:46:19.523: E/AndroidRuntime(4279): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.content.ContextWrapper.getApplicationContext(ContextWrapper.java:105)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at com.example.schoolandrevisiontimetable.Input_slessontime.getAmountOfDaysUsed(Input_slessontime.java:95)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at com.example.schoolandrevisiontimetable.Input_slessontime.&lt;init&gt;(Input_slessontime.java:30)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at java.lang.reflect.Constructor.newInstance(Native Method)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at java.lang.Class.newInstance(Class.java:1572)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.Instrumentation.newActivity(Instrumentation.java:1088)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
  04-06 16:46:19.523: E/AndroidRuntime(4279):     ... 10 more
  </code></pre>
  
  <p>Here is the class it is returning null in 
  package com.example.schoolandrevisiontimetable;</p>
  
  <pre><code>import java.util.List;
  
  import com.astuetz.PagerSlidingTabStrip;
  
  
  import Database.DatabaseHelper;
  import Database.MC_sschoolday;
  import android.app.Activity;
  import android.app.ActionBar;
  import android.app.Fragment;
  import android.content.Context;
  import android.os.Bundle;
  import android.support.v4.app.FragmentActivity;
  import android.support.v4.app.FragmentManager;
  import android.support.v4.app.FragmentPagerAdapter;
  import android.support.v4.view.ViewPager;
  import android.util.TypedValue;
  import android.view.LayoutInflater;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.View;
  import android.view.ViewGroup;
  import android.os.Build;
  
  public class Input_slessontime extends FragmentActivity {
      DatabaseHelper db;
      String[] days = new String[getAmountOfDaysUsed()];
      private PagerSlidingTabStrip tabs;
      private ViewPager pager;
      private MyPagerAdapter adapter;
  
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.fragment_input_slessontime);
  
  
          tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
          pager = (ViewPager) findViewById(R.id.pager);
          adapter = new MyPagerAdapter(getSupportFragmentManager());
  
          final int pageMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 4, getResources()
                  .getDisplayMetrics());
          pager.setPageMargin(pageMargin);
  
          tabs.setViewPager(pager);
  
  
          if (savedInstanceState == null) {
              getFragmentManager().beginTransaction()
                      .add(R.id.container, new PlaceholderFragment()).commit();
          }
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.input_slessontime, 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();
          if (id == R.id.action_settings) {
              return true;
          }
          return super.onOptionsItemSelected(item);
      }
  
      /**
       * A placeholder fragment containing a simple view.
       */
      public static class PlaceholderFragment extends Fragment {
  
          public PlaceholderFragment() {
          }
  
          @Override
          public View onCreateView(LayoutInflater inflater, ViewGroup container,
                  Bundle savedInstanceState) {
              View rootView = inflater.inflate(R.layout.fragment_input_slessontime, container, false);
              return rootView;
          }
      }
  
      public int getAmountOfDaysUsed(){
          db = new DatabaseHelper(getApplicationContext());   
  
          List&lt;MC_sschoolday&gt; MC_sschoolday = db.getAllSSchoolDays(); //gets all the lessons and stores them in a list
  
          int amountOfDaysUsed=0;
  
          MC_sschoolday[] sday = new MC_sschoolday[7]; 
          for (int i =0; i&lt;7; i++){
              sday[i]=MC_sschoolday.get(i); //stores the lessons in an array
  
           }
  
          for (int i =0; i&lt;7; i++){
              if(sday[i].getUsed().equals("y")){
                  amountOfDaysUsed++;
              }
          } 
  
          db.close();
          return amountOfDaysUsed; 
      }
      public void getTitles(){
          db = new DatabaseHelper(getApplicationContext());   
          MC_sschoolday[] sday = new MC_sschoolday[7];
          List&lt;MC_sschoolday&gt; schoolday = db.getAllSSchoolDays();
  
          int usedCount2=0;
          for (int i =0; i&lt; db.getAllSSchoolDays().size(); i++){
              sday[i]=schoolday.get(i);
              if(sday[i].getUsed().equals("y")){
                  days[usedCount2] = sday[i].getschool_day();
                  usedCount2++;
              }
          }
          db.close();
      }
  
  
      public class MyPagerAdapter extends FragmentPagerAdapter {
  
  
  
          public MyPagerAdapter(FragmentManager fm) {
              super(fm);
          }
  
          @Override
          public CharSequence getPageTitle(int position) {
              return days[position];
          }
  
          @Override
          public int getCount() {
              return getAmountOfDaysUsed();
          }
  
          public android.support.v4.app.Fragment switchFragmentDay(int num) {
              DatabaseHelper db;
              db = new DatabaseHelper(getApplicationContext());   
              MC_sschoolday[] sday = new MC_sschoolday[7];
              List&lt;MC_sschoolday&gt; schoolday = db.getAllSSchoolDays();
              int usedCount1=getAmountOfDaysUsed();
  
  
              int [] dayID = new int[usedCount1];
  
              int usedCount2=0;
              for (int i =0; i&lt; db.getAllSSchoolDays().size(); i++){
                  sday[i]=schoolday.get(i);
                  if(sday[i].getUsed().equals("y")){
                      dayID[usedCount2] = (int) sday[i].getSchool_day_id();
                      usedCount2++;
                  }
              }
              db.close();
              switch (dayID[num]){
              case 1:
                  return new Input_slessontime_monday();
              case 2:
                  return new Input_slessontime_tuesday();
              case 3:
                  return new Input_slessontime_wednesday();
              case 4:
                  return new Input_slessontime_thursday();
              case 5:
                  return new Input_slessontime_friday();
              case 6:
                  return new Input_slessontime_saturday();
              case 7:
                  return new Input_slessontime_sunday();
              }
              return null;
  
          }
  
          @Override
          public android.support.v4.app.Fragment getItem(int position) {
  
              switch (position){              
              case 0:
                  return switchFragmentDay(0);
              case 1:
                  return switchFragmentDay(1);
              case 2:
                  return switchFragmentDay(2);
              case 3:
                  return switchFragmentDay(3);
              case 4:
                  return switchFragmentDay(4);
              case 5:
                  return switchFragmentDay(5);
              case 6:
                  return switchFragmentDay(6);
  
              }
  
          return null;
          }
  
      }
  
  
  }
  </code></pre>
  
  <p>thanks for your help!</p>