Can not find my mistake, java.lang.NullPointerException: Attempt to get length of null array

I am new to programming thats why I dont understand the Info to What is a Null Pointer Exception, and how do I fix it? .

I wrote a app, where you read the isbn of a book and you will get the bookinfo, bookimage via googlebooksAPI.

I managed that the data inclusive the image will be stored in the sqlite db. I want to display the stored data in a listview. (I managed it before, but without storing the image - no Nullpointer error). There I get the error.

unfortunately I got this error: java.lang.NullPointerException: Attempt to get length of null array

Following my Logcat und the used Activities:

Logcat:

Process: com.kasutwentyseven.gui4selfshelf, PID: 32327
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kasutwentyseven.gui4selfshelf/com.kasutwentyseven.gui4selfshelf.Books.BookDataListActivity}: java.lang.NullPointerException: Attempt to get length of null array
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2357)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2419)
at android.app.ActivityThread.access$900(ActivityThread.java:154)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5291)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
Caused by: java.lang.NullPointerException: Attempt to get length of null array
at com.kasutwentyseven.gui4selfshelf.Books.BookDataListActivity.onCreate(BookDataListActivity.java:130)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2310)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2419) 
at android.app.ActivityThread.access$900(ActivityThread.java:154) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5291) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 

I think the error is in the onCreate method of the BookDataListActivity

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.book_data_list_layout);

    Typeface myTypeface = Typeface.createFromAsset(getAssets(), "Lobster.ttf");

    TextView myTextView = (TextView) findViewById(R.id.text_yourbooks);
    myTextView.setTypeface(myTypeface);

    booklistView = (ListView) findViewById(R.id.book_list_view);
    inputSearch = (EditText) findViewById(R.id.search_bar);

    bookListDataAdapter = new BookListDataAdapter(getApplicationContext(), R.layout.row_book_layout);
    booklistView.setAdapter(bookListDataAdapter);


    //onItemClickListener
    booklistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            Intent intent = new Intent(getApplicationContext(), BookInfoActivity.class);



            editTextBooktitle = (TextView) view.findViewById(R.id.text_book_title);
            String book_title = editTextBooktitle.getText().toString();
            intent.putExtra(EXTRA_MSG1, book_title);

            editTextBookauthor = (TextView) view.findViewById(R.id.text_book_author);
            String bookauthor = editTextBookauthor.getText().toString();
            intent.putExtra(EXTRA_MSG2, bookauthor);

            editTextBookdate = (TextView) view.findViewById(R.id.text_book_date);
            String bookdate = editTextBookdate.getText().toString();
            intent.putExtra(EXTRA_MSG3, bookdate);

            editTextBookrating = (TextView) view.findViewById(R.id.text_book_rating);
            String bookrating = editTextBookrating.getText().toString();
            intent.putExtra(EXTRA_MSG4, bookrating);

            editTextBookshelf = (TextView) view.findViewById(R.id.text_book_shelf);
            String bookshelf = editTextBookshelf.getText().toString();
            intent.putExtra(EXTRA_MSG5, bookshelf);

            startActivity(intent);

        }

    });


    inputSearch.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            bookListDataAdapter.getFilter().filter(s);
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

    bookDBHelper = new BookDBHelper(getApplicationContext());
    sqLiteDatabaseBooks = bookDBHelper.getReadableDatabase();
    cursor2 = bookDBHelper.getInformations(sqLiteDatabaseBooks);
    if (cursor2.moveToFirst()) {
        do {
            String booktitle, bookauthor, bookdate, bookrating, bookshelf;
            Bitmap bookimage;

            byte[] blob= cursor2.getBlob(0);
            bookimage = BitmapFactory.decodeByteArray(blob,0,blob.length);
            booktitle = cursor2.getString(1);
            bookauthor = cursor2.getString(2);
            bookdate = cursor2.getString(3);
            bookrating = cursor2.getString(4);
            bookshelf = cursor2.getString(5);

            BookDataProvider bookDataProvider = new BookDataProvider(bookimage, booktitle, bookauthor, bookdate, bookrating, bookshelf);
            bookListDataAdapter.add(bookDataProvider);

        } while (cursor2.moveToNext());
    }
}

}

I think you will need the methods for adding and getting the Info data for the listview - It is in the BOOKDBHelper Activity

public class BookDBHelper extends SQLiteOpenHelper{

private static final String DATABASE_BOOKS_NAME = "BookINFO.DB";
private static final int DATABASE_BOOKS_VERS = 2;
private static final String CREATE_QUERY_BOOKS =
        "CREATE TABLE "
                + BookContent.NewBookInfo.TABLE_NAME_BOOKS
                +"("
                + BookContent.NewBookInfo.BOOK_IMAGE +" BLOB, "
                + BookContent.NewBookInfo.BOOK_TITLE+" TEXT, "
                + BookContent.NewBookInfo.BOOK_AUTHOR+" TEXT, "
                + BookContent.NewBookInfo.BOOK_DATE+" TEXT, "
                + BookContent.NewBookInfo.BOOK_RATING+" TEXT, "
                + BookContent.NewBookInfo.BOOK_SHELF+" TEXT);";


public BookDBHelper(Context context){
    super(context, DATABASE_BOOKS_NAME, null, DATABASE_BOOKS_VERS);
    Log.e("DATABASE OPERATIONS", " DATABASE CREATED");
}

@Override
public void onCreate(SQLiteDatabase bookdb) {

    bookdb.execSQL(CREATE_QUERY_BOOKS);
    Log.e("DATABASE OPERATIONS", " DATABASE CREATED");
}
public void addInformations(byte[] image, String booktitle, String bookauthor, String bookdate, String bookrating, String bookshelf, SQLiteDatabase bookdb)
{

    ContentValues contentValues = new ContentValues();
    contentValues.put(BookContent.NewBookInfo.BOOK_IMAGE, image);
    contentValues.put(BookContent.NewBookInfo.BOOK_TITLE, booktitle);
    contentValues.put(BookContent.NewBookInfo.BOOK_AUTHOR, bookauthor);
    contentValues.put(BookContent.NewBookInfo.BOOK_DATE, bookdate);
    contentValues.put(BookContent.NewBookInfo.BOOK_RATING, bookrating);
    contentValues.put(BookContent.NewBookInfo.BOOK_SHELF, bookshelf);

    bookdb.insert(BookContent.NewBookInfo.TABLE_NAME_BOOKS, null, contentValues);
    Log.e("DATABASE OPERATIONS", "ON ROW INSERTED");
}
public Cursor getInformations(SQLiteDatabase bookdb){
    Cursor cursor2;
        String[] projections = {
                BookContent.NewBookInfo.BOOK_IMAGE,
                BookContent.NewBookInfo.BOOK_TITLE,
                BookContent.NewBookInfo.BOOK_AUTHOR,
                BookContent.NewBookInfo.BOOK_DATE,
                BookContent.NewBookInfo.BOOK_RATING,
                BookContent.NewBookInfo.BOOK_SHELF};
    cursor2 = bookdb.query(BookContent.NewBookInfo.TABLE_NAME_BOOKS, projections,null, null, null, null, null);
    return cursor2;
}

I dont find my error, thats why I am writing to you. Maybe you experts can help me learn something new.