title: Android: NullPointerException on getWritableDatabase()
body: <p>Here is where I try to access the database:</p>
  
  <pre><code>UserDataAdapter dbHelper = new UserDataAdapter(this);
  dbHelper.open();
  dbHelper.createNetwork(network);
  dbHelper.close();
  </code></pre>
  
  <p>UserDataAdapter.java:</p>
  
  <pre><code>public UserDataAdapter open() throws SQLException {
          dbHelper = new DatabaseHelper(context); // of class DatabaseHelper
          database = dbHelper.getWritableDatabase(); // this line!!   
          return this;
      }
  </code></pre>
  
  <p>DatabaseHelper.java:</p>
  
  <pre><code>public DatabaseHelper(Context context) {
          super(context, Defines.DATABASE_NAME, null, Defines.DATABASE_VERSION);
      }
  
  @Override
      public void onCreate(SQLiteDatabase db) {
          db.execSQL(Defines.DATABASE_CREATE_TAXI_SERVICE_DATABASE);
      }
  </code></pre>
  
  <p>Crash:
  09-13 18:12:33.119: E</p>
  
  <pre><code>RROR/AndroidRuntime(7488): FATAL EXCEPTION: main
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488): java.lang.NullPointerException
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.basind.testapp.database.UserDataAdapter.open(UserDataAdapter.java:29)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.basind.testapp.FetchNetworks.addToDatabase(FetchNetworks.java:107)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.basind.testapp.FetchNetworks.access$1(FetchNetworks.java:105)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.basind.testapp.FetchNetworks$1.onResponseReceived(FetchNetworks.java:75)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.basind.testapp.async.CallbackWrapper.run(CallbackWrapper.java:15)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.os.Handler.handleCallback(Handler.java:587)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.os.Handler.dispatchMessage(Handler.java:92)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.os.Looper.loop(Looper.java:145)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at android.app.ActivityThread.main(ActivityThread.java:4937)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at java.lang.reflect.Method.invokeNative(Native Method)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at java.lang.reflect.Method.invoke(Method.java:521)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
  09-13 18:12:33.119: ERROR/AndroidRuntime(7488):     at dalvik.system.NativeStart.main(Native Method)
  </code></pre>
  
  <p>Other details:</p>
  
  <ul>
  <li>Target: android-7</li>
  <li>Test Device: HTC Desire</li>
  </ul>