title: getReadableDatabase()' on a null object reference
body: <p>I'm new, I am doing some debugging. I am having some difficulty that I am having some difficulty conveying.</p>
  
  <p>I am trying to read from a SQLite database I have created in another activity.</p>
  
  <p>My current problem appears to be: </p>
  
  <pre><code>SQLiteDatabase db = myOpenHelper.getReadableDatabase();
  </code></pre>
  
  <p>which should point to my database helper class. </p>
  
  <pre><code>public class SecondActivity extends ListActivity {
  
      CustomOpenHelper myOpenHelper;
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_second);
  
          displayDataInTable();
  
      }
  
          void displayDataInTable() {
          List&lt;String&gt; values = queryTable();
  
          if (values != null) {
              ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(SecondActivity.this, android.R.layout.simple_list_item_1, values);
              setListAdapter(adapter);
  
  
          }
  
      }
  
      List&lt;String&gt; queryTable() {
          List&lt;String&gt; player = new ArrayList&lt;String&gt;();
  
          SQLiteDatabase db = myOpenHelper.getReadableDatabase();
          Cursor cursor = db.query(true, CustomOpenHelper.TABLE_NAME, new String[]{"_id, name, score"}, null, null, null, null, null, null, null);
  
          while (cursor.moveToNext()) {
              int id = cursor.getInt(cursor.getColumnIndex("_id"));
              String name = cursor.getString(cursor.getColumnIndex("name"));
              int score = cursor.getInt(cursor.getColumnIndex("score"));
              player.add(id + " --&gt; the player " + name + " has got a score of " + score + "s");
          }
  
          return player;
      }
  
  
  
      @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_second, 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;
          }
  
          return super.onOptionsItemSelected(item);
      }
  }
  </code></pre>
  
  <p>The LogCat error (extract):</p>
  
  <pre><code>09-28 20:41:57.039    1271-1285/system_process W/ActivityManager﹕ Launch timeout has expired, giving up wake lock!
  09-28 20:42:23.468    3642-3642/com.example.eagle.sqlite2activitytest D/AndroidRuntime﹕ Shutting down VM
  09-28 20:42:23.486    3642-3642/com.example.eagle.sqlite2activitytest E/AndroidRuntime﹕ FATAL EXCEPTION: main
      Process: com.example.eagle.sqlite2activitytest, PID: 3642
      java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.eagle.sqlite2activitytest/com.example.eagle.sqlite2activitytest.SecondActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase com.example.eagle.sqlite2activitytest.CustomOpenHelper.getReadableDatabase()' on a null object reference
              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
              at android.app.ActivityThread.-wrap11(ActivityThread.java)
              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
              at android.os.Handler.dispatchMessage(Handler.java:102)
              at android.os.Looper.loop(Looper.java:148)
              at android.app.ActivityThread.main(ActivityThread.java:5417)
              at java.lang.reflect.Method.invoke(Native Method)
              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
       Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase com.example.eagle.sqlite2activitytest.CustomOpenHelper.getReadableDatabase()' on a null object reference
              at com.example.eagle.sqlite2activitytest.SecondActivity.queryTable(SecondActivity.java:43)
              at com.example.eagle.sqlite2activitytest.SecondActivity.displayDataInTable(SecondActivity.java:29)
              at com.example.eagle.sqlite2activitytest.SecondActivity.onCreate(SecondActivity.java:24)
              at android.app.Activity.performCreate(Activity.java:6237)
              at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
              at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
              at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
              at android.app.ActivityThread.-wrap11(ActivityThread.java)
              at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
              at android.os.Handler.dispatchMessage(Handler.java:102)
              at android.os.Looper.loop(Looper.java:148)
              at android.app.ActivityThread.main(ActivityThread.java:5417)
              at java.lang.reflect.Method.invoke(Native Method)
              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
  09-28 20:42:23.493    1271-1721/system_process W/ActivityManager﹕ Force finishing activity com.example.eagle.sqlite2activitytest/.SecondActivity
  </code></pre>
  
  <p>What do you think?</p>