Android App Crashes on Startup: SQLite NullPointerException in ContactsFragment

It looks like you accidentally created a context local variable instead of using the instance variable.

So, context is null when you pass it into MyDBHandler, so when you call this.getWritableDatabase(), this is null. As a result, you get the NullPointerException, as you can see in the log:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.database.sqlite.SQLiteDatabase android.content.Context.openOrCreateDatabase(java.lang.String, int, android.database.sqlite.SQLiteDatabase$CursorFactory, android.database.DatabaseErrorHandler)' on a null object reference        at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224)        at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)

Try moving all of the Context related code to onActivityCreated() to ensure you have a valid Context, and make sure to use the instance variable instead of a local variable:

public class ContactsFragment extends ListFragment implements LoaderManager.LoaderCallbacks<Cursor> {private CursorAdapter mAdapter;private Context context; //this is the Context you will useTextView idView;@Overridepublic void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    // create adapter once    //Context context = getActivity(); //Here was the problem    //int layout = R.layout.activity_list_item_1;    //Cursor c = null; // there is no cursor yet    //int flags = 0; // no auto-requery! Loader requeries.    //mAdapter = new SimpleCursorAdapter(context, layout, c, FROM, TO, flags);}public void ContactsDb(Context context) {    this.context=context;}Uri contentUri = ContactsContract.CommonDataKinds.Phone.CONTENT_URI;String[] PROJECTION = {        ContactsContract.Contacts.HAS_PHONE_NUMBER,        ContactsContract.Contacts._ID, // _ID is always required        ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME_PRIMARY, // that is what we want to display        Contacts.TIMES_CONTACTED,        ContactsContract.CommonDataKinds.Phone.NUMBER};@Overridepublic void onActivityCreated(Bundle savedInstanceState) {    super.onActivityCreated(savedInstanceState);    //Add this here:    context = getActivity(); //use the instance variable    int layout = R.layout.activity_list_item_1;    Cursor c = null; // there is no cursor yet    int flags = 0; // no auto-requery! Loader requeries.    mAdapter = new SimpleCursorAdapter(context, layout, c, FROM, TO, flags);    // each time we are started use our listadapter    setListAdapter(mAdapter);    // and tell loader manager to start loading    getLoaderManager().initLoader(0, null, this);}// columns requested from the database// and name should be displayed in the text1 textview in item layoutpublic String[] has_phone = {ContactsContract.Contacts.HAS_PHONE_NUMBER};    String phone = "0";    int dbPhone = 0;private  final String[] FROM = {Contacts.DISPLAY_NAME_PRIMARY, ContactsContract.CommonDataKinds.Phone.NUMBER};private final int[] TO = {android.R.id.text1, dbPhone};public void newContact (View view) {    //context should now be valid:    MyDBHandler dbHandler = new MyDBHandler(context, null, null, 1);    String name = Contacts.DISPLAY_NAME_PRIMARY;    int dbPhone =    Integer.parseInt(phone);    String status ="";    String blurb ="";    ContactsDb contacts =            new ContactsDb(name, dbPhone, status, blurb);    dbHandler.addContact(contacts);}//........

make object from db class in onCreateViewHolder method in adapter to solve this error