Why is getBlob() retrieving Integer data from my Blob column in my database?

Question

I am trying to display the data from my SQLite database to the recycler views. The data I am trying to display is an image & text. For the images in my database, I converted the image resources into bitmaps then into bytes & stored the bytes in my Blob column. However when I am trying to retrieve the bytes from the column using the getBlob() I receive an exception.

The exception is android.database.sqlite.SQLiteException: unknown error (code 0 SQLITE_OK): INTEGER data in nativeGetBlob. I know that this exception is occurring because the getBlob() retrieves Integer data from my Blob column. But I don't understand I put bytes into my Blob column, so why is getBlob() retrieving Integer data?

I have tried using the getInt() but that doesn't work because my adapter uses BitmapFactory.decodeByteArray() which expects a byte parameter to convert the bytes from my column into a bitmap.

SQLite database:

package com.myapps.myapplication;

import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

import java.io.ByteArrayOutputStream;
import java.util.ArrayList;

public class MyDatabaseHelper extends SQLiteOpenHelper {

private static final String DB_NAME = "starbuzz";
private static final int DB_VERSION = 6;
private Context context;
private ArrayList <Bitmap> bitmapArray;
private byte [] byteArray;

public MyDatabaseHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
    this.context = context;
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("CREATE TABLE GROCERY_ITEMS (" + "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + "NAME TEXT, " + "IMAGE_RESOURCE_ID BLOB);");

    upgradeDatabase(db);
}

public void upgradeDatabase (SQLiteDatabase db) {
    convertToBitmap();
    byteArray = convertToByte();
    addItems(db);
}

public void convertToBitmap () {
    Bitmap faan = BitmapFactory.decodeResource(context.getResources(), R.drawable.faan);
    Bitmap milk = BitmapFactory.decodeResource (context.getResources(), R.drawable.milk);
    Bitmap egg = BitmapFactory.decodeResource (context.getResources(), R.drawable.egg);
    Bitmap toilet_tissue = BitmapFactory.decodeResource (context.getResources(), R.drawable.toilet_tissue);
    Bitmap kitchen_tissue = BitmapFactory.decodeResource (context.getResources(), R.drawable.kitchen_tissue);
    Bitmap bread = BitmapFactory.decodeResource (context.getResources(), R.drawable.bread);
    Bitmap potatoe = BitmapFactory.decodeResource (context.getResources(), R.drawable.potatoe);
    Bitmap onion = BitmapFactory.decodeResource (context.getResources(), R.drawable.onion);
    Bitmap flour = BitmapFactory.decodeResource (context.getResources(), R.drawable.flour);
    Bitmap tomatoe = BitmapFactory.decodeResource (context.getResources(), R.drawable.tomatoe);
    Bitmap corriandor = BitmapFactory.decodeResource (context.getResources(), R.drawable.corriandor);

    bitmapArray = new ArrayList <Bitmap> ();

    bitmapArray.add(faan);
    bitmapArray.add (milk);
    bitmapArray.add (egg);
    bitmapArray.add (toilet_tissue);
    bitmapArray.add (kitchen_tissue);
    bitmapArray.add (bread);
    bitmapArray.add (potatoe);
    bitmapArray.add (onion);
    bitmapArray.add (flour);
    bitmapArray.add (tomatoe);
    bitmapArray.add (corriandor);

}

public byte [] convertToByte () {

    ByteArrayOutputStream stream = new ByteArrayOutputStream ();

    for (Bitmap bitmap : bitmapArray) {
        bitmap.compress (Bitmap.CompressFormat.PNG, 0, stream);
    }

    return stream.toByteArray();
}

public static Bitmap getImages (byte [] image) {
    return BitmapFactory.decodeByteArray(image, 0, image.length);
}

public void addItems (SQLiteDatabase db) {

    byte faan = byteArray [0];
    byte milk = byteArray [1];
    byte egg = byteArray [2];
    byte toilet_tissue = byteArray [3];
    byte kitchen_tissue = byteArray [4];
    byte bread = byteArray [5];
    byte potatoe = byteArray [6];
    byte onion = byteArray [7];
    byte flour = byteArray [8];
    byte tomatoe = byteArray [9];
    byte corriandor = byteArray [10];

    insertItems (db, "Faan", faan);
    insertItems (db, "Milk", milk);
    insertItems (db, "Egg", egg);
    insertItems (db, "Toilet Tissue", toilet_tissue);
    insertItems (db, "Kitchen Tissue", kitchen_tissue);
    insertItems (db, "Bread", bread);
    insertItems (db, "Potatoe", potatoe);
    insertItems (db, "Onion", onion);
    insertItems (db, "Flour", flour);
    insertItems (db, "Tomatoe", tomatoe);
    insertItems (db, "Corriandor", corriandor);

}

public void insertItems (SQLiteDatabase db, String name, byte image) {
    ContentValues contentValues = new ContentValues();
    contentValues.put ("NAME", name);
    contentValues.put ("IMAGE_RESOURCE_ID", image);

    db.insert ("GROCERY_ITEMS", null, contentValues);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("CREATE TABLE GROCERY_ITEMS (" + "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + "NAME TEXT, " + "IMAGE_RESOURCE_ID BLOB);");

    upgradeDatabase(db);
}
}

Recycler View class

package com.myapps.myapplication;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

public class grocery_item extends AppCompatActivity {

SQLiteDatabase db;
Cursor cursor;

protected void onCreate (Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.item_grocery);

    accessDataBase();

    RecyclerView groceryRecycler = (RecyclerView) findViewById(R.id.grocery_recycler_view);

    captionedImagesAdapter adapter = new captionedImagesAdapter (this, cursor);
    GridLayoutManager layoutManager = new GridLayoutManager(this, 2, GridLayoutManager.VERTICAL, false);
    groceryRecycler.setLayoutManager(layoutManager);
    groceryRecycler.setAdapter (adapter);
}

public void accessDataBase () {
    MyDatabaseHelper databaseHelper = new MyDatabaseHelper(this);

    try {

        db = databaseHelper.getReadableDatabase();

        cursor = db.query ("GROCERY_ITEMS", new String[] {"NAME", "IMAGE_RESOURCE_ID"}, null, null, null, null, null);

    } catch (SQLiteException e) {
        e.printStackTrace();
    }
}
}

Recycler view adapter:

package com.myapps.myapplication;

import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.recyclerview.widget.RecyclerView;
import androidx.cardview.widget.CardView;

public class captionedImagesAdapter extends RecyclerView.Adapter <captionedImagesAdapter.ViewHolder> {

private Context context;
private Cursor cursor;

public captionedImagesAdapter (Context context, Cursor cursor) {
    this.context = context;
    this.cursor = cursor;
}

public captionedImagesAdapter.ViewHolder onCreateViewHolder (ViewGroup parent, int viewType) {
    LayoutInflater inflater = LayoutInflater.from(context);
    CardView cv = (CardView) inflater.inflate(R.layout.card_view, parent, false);

    return new ViewHolder (cv);
}

public void onBindViewHolder(ViewHolder holder, int position) {
    if (!cursor.moveToPosition(position)) {
        return;
    }

    String info_text = cursor.getString (0);
    byte [] info_image = cursor.getBlob(1);

    Bitmap bitmap = MyDatabaseHelper.getImages(info_image);

    holder.textView.setText(info_text);
    holder.imageView.setImageBitmap(bitmap);
}

public int getItemCount() {
    return cursor.getCount();
}

public static class ViewHolder extends RecyclerView.ViewHolder {
    private ImageView imageView;
    private TextView textView;

    public ViewHolder(CardView view) {
        super(view);
        imageView = view.findViewById(R.id.info_image);
        textView = view.findViewById(R.id.info_text);
    }
}
}

Exception:

android.database.sqlite.SQLiteException: unknown error (code 0 SQLITE_OK): INTEGER data in nativeGetBlob 
    at android.database.CursorWindow.nativeGetBlob(Native Method)
    at android.database.CursorWindow.getBlob(CursorWindow.java:434)
    at android.database.AbstractWindowedCursor.getBlob(AbstractWindowedCursor.java:47)
    at com.myapps.myapplication.captionedImagesAdapter.onBindViewHolder(captionedImagesAdapter.java:43)
    at com.myapps.myapplication.captionedImagesAdapter.onBindViewHolder(captionedImagesAdapter.java:14)
    at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7178)
    at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7258)
    at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6125)
    at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6391)
    at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6231)
    at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6227)
    at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2330)
    at androidx.recyclerview.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:572)
    at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
    at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:668)
    at androidx.recyclerview.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
    at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4230)
    at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3941)
    at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4499)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:786)
    at android.view.View.layout(View.java:22085)
    at android.view.ViewGroup.layout(ViewGroup.java:6290)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3333)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2810)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1930)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7988)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1154)
    at android.view.Choreographer.doCallbacks(Choreographer.java:977)
    at android.view.Choreographer.doFrame(Choreographer.java:893)
    at android.view.Choreographer$FrameHandler.handleMessage(Choreographer.java:1082)
    2020-08-12 13:34:17.755 14399-14399/com.myapps.myapplication E/AndroidRuntime:     at 
    android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7682)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)

Answer 1

Where to begin?

1. you name the column IMAGE_RESOURCE_ID which indicates that you store some kind of identifying number in it, but it's of type BLOB which indicates that the content is actually the image data itself. That confusion is not in itself a problem, but indicates that the code hasn't been written with a clear direction in mind.
2. You store all images into a single stream with no way to pick out the separate images. If you wanted to store the actual data in a database, then each bitmap should be encoded into a separate byte[].
3. You take the first 11 bytes of the resulting mega-byte[] and store only those in the database (in 11 different rows as well). Those bytes are probably just the beginning of the header of the first image and have no useful meaning on their own.

My suggestion: if you want to store the actual data, change the convertToBytes method to take a Bitmap argument and call it once for each Bitmap you want to store in the database.

Answer 2

It sounds like the second column in your query isn't the blob you thought it was; you're accessing it with .getBlob(1), which means: Take the value of the second column and give it to me as a blob, and the error seems to indicate: .. no can do, it's not a blob, it's an integer.

You haven't pasted where you make your AbstractWindowedCursor object; it is the cursor that is passed into the constructor of your captionedImagesAdapter class. What query is behind this? I bet it's SELECT foo, bar, baz FROM something, where bar is not, actually, a blob value. For example, if you did SELECT * FROM GROCERY_ITEMS, then the first column (.getInt(0) for example) is the id column, the second is the name (text), and the third is the blob. You'd end up getting an error similar to this one if you attempted to run .getBlob(1) on that, because 1 is the wrong number.