title: Attempt to invoke virtual method 'android.database.Cursor android.database.sqlite.SQLiteDatabase.query on null object reference
body: <p>I have an activity in which i am trying to get the list of data based on some condition . This selectsome() function is in the SQLiteOpenHelper subclass.</p>
  
  <pre><code>MyDBHandler dbhelper = new MyDBHandler(this);
  Cursor cursor;
  cursor = dbhelper.selectSome(value);
  </code></pre>
  
  <p>In class MyDBHelper.java     </p>
  
  <pre><code>public Cursor selectSome(String arg)
  
  {
  
      String columns[]=new String[]{"_id","_hotelname","_city","_imageSrc","_rent","_address"};
      String selarg[]={arg};
      Cursor c=db.query(TABLE_NAME,columns,"city = ?",selarg, null,null,null);
     return c;
  }
  </code></pre>
  
  <p>I am getting this error please help.</p>
  
  <pre><code>09-01 18:08:00.394 E/AndroidRuntime( 6246): FATAL EXCEPTION: main
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246): Process: com.example.hari.testapp, PID: 6246
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.hari.testapp/com.example.hari.testapp.HotelList}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor android.database.sqlite.SQLiteDatabase.query(java.lang.String, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, java.lang.String, java.lang.String)' on a null object reference
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.app.ActivityThread.access$800(ActivityThread.java:151)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.os.Handler.dispatchMessage(Handler.java:102)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.os.Looper.loop(Looper.java:135)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at android.app.ActivityThread.main(ActivityThread.java:5257)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at java.lang.reflect.Method.invoke(Native Method)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at java.lang.reflect.Method.invoke(Method.java:372)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.Cursor android.database.sqlite.SQLiteDatabase.query(java.lang.String, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, java.lang.String, java.lang.String)' on a null object reference
  
  09-01 18:08:00.394 E/AndroidRuntime( 6246):     at com.example.hari.testapp.databaseFiles.MyDBHandler.selectSome(MyDBHandler.java:113)
  </code></pre>