title: Android [IllegalArgumentException: the bind value at index 1 is null] for no apparent reason
body: <p>I am trying to get some methods concerning databases working when referenced from two different activities which causes me to re-initialize the whole database with different contexts in the same class. It works from one activity but when the database is closed,  initialized and opened in the other activity it causes an IllegalArgumentException. This makes no sense to me as I didn't change any methods connected directly to the database and it was working flawlessly when the code was separated in two classes.</p>
  
  <p>Stacktrace:</p>
  
  <pre><code>05-09 20:44:42.661: E/AndroidRuntime(953): FATAL EXCEPTION: main
  05-09 20:44:42.661: E/AndroidRuntime(953): java.lang.RuntimeException: Unable to resume activity {maturaarbeit.nicola_pfister.marks/maturaarbeit.nicola_pfister.marks.Marks}: java.lang.IllegalArgumentException: the bind value at index 1 is null
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2575)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2603)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2089)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.os.Handler.dispatchMessage(Handler.java:99)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.os.Looper.loop(Looper.java:137)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.main(ActivityThread.java:4745)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at java.lang.reflect.Method.invokeNative(Native Method)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at java.lang.reflect.Method.invoke(Method.java:511)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at dalvik.system.NativeStart.main(Native Method)
  05-09 20:44:42.661: E/AndroidRuntime(953): Caused by: java.lang.IllegalArgumentException: the bind value at index 1 is null
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteProgram.bindString(SQLiteProgram.java:164)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteProgram.bindAllArgsAsStrings(SQLiteProgram.java:200)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1161)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1032)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at maturaarbeit.nicola_pfister.marks.database.DBAdapter.getAverage(DBAdapter.java:200)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at maturaarbeit.nicola_pfister.marks.MyMenu.getData(MyMenu.java:71)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at maturaarbeit.nicola_pfister.marks.Marks.onResume(Marks.java:52)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1184)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.Activity.performResume(Activity.java:5082)
  05-09 20:44:42.661: E/AndroidRuntime(953):  at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2565)
  05-09 20:44:42.661: E/AndroidRuntime(953):  ... 12 more
  </code></pre>
  
  <p>Exception throwing method in Marks (menu.onResume):</p>
  
  <pre><code>private final Context context;
  
  private DatabaseHelper DBHelper;
  private SQLiteDatabase db;
  
  MyMenu menu = new MyMenu(this);
  
      ListView lView;
      View view;
  
      private String TAG = "Marks";
      @Override
          protected void onResume() {
              super.onResume();
              menu.closedb();
              menu.opendb(TAG);
              menu.getData(lView, view);
  
          }
  </code></pre>
  
  <p>Involved methods in MyMenu (exception on db.open()):</p>
  
  <pre><code>DBAdapter db;
  
  public void opendb(String caller) {
          db = new DBAdapter(context);
          this.caller = caller; //Is used to distinguish which activity called the class; not involved in this problem
          db.open();
  
      }
  
      public void closedb() {
          db.clean();
          db.close();
      }
  
  @SuppressWarnings("deprecation")
  public String getData(final ListView lView, final View view) {
      SimpleCursorAdapter adapter = null;
      if (caller == "Main") {
          adapter = new SimpleCursorAdapter(context, 
                  android.R.layout.simple_list_item_activated_1, 
                  db.getAllSubjects(), 
                  new String[] { "subject" }, 
                  new int[] { android.R.id.text1 });
      } else if (caller == "Marks") {
          adapter = new SimpleCursorAdapter(context, 
                  android.R.layout.simple_list_item_activated_1, 
                  db.getMarks(subject), 
                  new String[] {"value"}, 
                  new int[] { android.R.id.text1 });
  
          Cursor cursor = db.getAverage(selection);
          average = cursor.getDouble(cursor.getColumnIndexOrThrow(DBAdapter.KEY_VALUE));
  
          if (average != 0.0) {
              TextView text = new TextView(context);
              text =  (TextView)view.findViewById(R.id.marks_average);
              text.setText(context.getString(R.string.average) + " " + average);
              text.setBackgroundColor(context.getResources().getColor(R.color.lightgrey));
          } else {
              TextView text = new TextView(context);
              text =  (TextView)view.findViewById(R.id.marks_average);
              text.setText("");
              text.setBackgroundColor(context.getResources().getColor(android.R.color.transparent));
          }
      }
  </code></pre>
  
  <p>Involved methods in DBAdapter (works fine with one activity, throws exception on getAverage()):</p>
  
  <pre><code>public DBAdapter open() throws SQLException {
          db = DBHelper.getWritableDatabase();
          return this;
      }
  
      public void close() {
          DBHelper.close();
      }
  
      public boolean clean () {
          db.delete(DATABASE_TABLE_SUBJECTS, KEY_SUBJECT +"=?", new String[] {""});
          db.delete(DATABASE_TABLE_MARKS, KEY_VALUE + "=?", new String[] {""});
          return true;
      }
  
      public Cursor getAverage(String subject) throws SQLException {
      Cursor mCursor =
              db.query(true, DATABASE_TABLE_AVERAGE, new String[] {
                      KEY_ROWID,
                      KEY_SUBJECT,
                      KEY_VALUE
              },
              KEY_SUBJECT + "=?",
              new String[] {subject}, null, null, null, null);
      if (mCursor != null) {
          mCursor.moveToFirst();
      }
      return mCursor;
  }
  </code></pre>
  
  <p>I initially thought that the error lies in the open() method but on reviewing the stacktrace I found that the exception is thrown by getAverage() which confuses me because it is not even called at this point. I assume there is something missing for the correct initialization of the DBAdapter class in the Marks activity but can't find the culprit.
  If you need any more information or code for solving the puzzle don't hesitate to let me know. 
  Thanks for your very much appreciated help!</p>