Android - sqlite gridview lag

Question

私は研究を行ったことがありますが、明確な説明が見つからなかったので、前に尋ねられたことは分かっていますが、解決策はまだありません。

私は、sqliteによって読み込まれるgridViewを持っています。問題は、私のgridViewのスクロールが遅れていることです。私のコード -

---

アダプター;

public class FoodListAdapter extends BaseAdapter { 

private Context context; 
private int layout; 
private ArrayList<Food> foodsList; 

public FoodListAdapter(Context context, int layout, ArrayList<Food> foodsList) { 
    this.context = context; 
    this.layout = layout; 
    this.foodsList = foodsList; 
} 

@Override 
public int getCount() { 
    return foodsList.size(); 
} 

@Override 
public Object getItem(int position) { 
    return foodsList.get(position); 
} 

@Override 
public long getItemId(int position) { 
    return position; 
} 

private class ViewHolder{ 
    CircularImageView imageView; 
    TextView txtName, txtPrice; 
} 

@Override 
public View getView(int position, View view, ViewGroup viewGroup) { 

    View row = view; 
    ViewHolder holder = new ViewHolder(); 


    if(row == null){ 
     LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     row = inflater.inflate(layout, null); 

     holder.txtName = (TextView) row.findViewById(R.id.txtName); 
     holder.txtPrice = (TextView) row.findViewById(R.id.txtPrice); 
     holder.imageView = (CircularImageView) row.findViewById(R.id.imgFood); 
     row.setTag(holder); 
    } 
    else { 
     holder = (ViewHolder) row.getTag(); 
    } 

    Food food = foodsList.get(position); 

    holder.txtName.setText(food.getName()); 
    holder.txtPrice.setText(food.getPrice()); 

    byte[] foodImage = food.getImage(); 
    Bitmap bitmap = BitmapFactory.decodeByteArray(foodImage, 0, foodImage.length); 
    holder.imageView.setImageBitmap(bitmap); 

    return row; 

} 

} 

---

活性;

public class FoodList extends AppCompatActivity { 

GridView gridView; 
ArrayList<Food> list; 
AdapterView adapterView; 
FoodListAdapter adapter = null; 

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

    sqLiteHelper = new SQLiteHelper(this, "FoodDB.sqlite", null, 1); 

    sqLiteHelper.queryData("CREATE TABLE IF NOT EXISTS FOOD(Id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR, price VARCHAR, image BLOB)"); 

    gridView = (GridView) findViewById(R.id.gridView); 
    list = new ArrayList<>(); 
    adapter = new FoodListAdapter(this, R.layout.food_items, list); 
    gridView.setAdapter(adapter); 

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

      String dataFromGrid; 
      dataFromGrid = ((TextView)(view.findViewById(R.id.txtName))).getText().toString(); 


      Intent i = new Intent(getApplicationContext(), FoodInfo.class); 

      i.putExtra("unfromfood",dataFromGrid); 
      startActivity(i); 


     } 
    }); 

    // get all data from sqlite 
    Cursor cursor = sqLiteHelper.getData("SELECT * FROM FOOD"); 
    list.clear(); 
    while (cursor.moveToNext()){ 
     int id = cursor.getInt(0); 
     String name = cursor.getString(1); 
     String price = cursor.getString(2); 
     byte[] image = cursor.getBlob(3); 

     list.add(new Food(name, price, image, id)); 
    } 
    adapter.notifyDataSetChanged(); 




} 

@Override 
public void onResume(){ 
    super.onResume(); 
    Cursor cursor = sqLiteHelper.getData("SELECT * FROM FOOD"); 
    list.clear(); 
    while (cursor.moveToNext()){ 
     int id = cursor.getInt(0); 
     String name = cursor.getString(1); 
     String price = cursor.getString(2); 
     byte[] image = cursor.getBlob(3); 

     list.add(new Food(name, price, image, id)); 
    } 
    adapter.notifyDataSetChanged(); 

} 

//Creating The Options Menu 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.menu_main, menu); 
    return true; 
} 

//Option Menu Click Events 
@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    int id = item.getItemId(); 
    // Settings 
    if (id == R.id.action_add_student) { 

     { 
      final Intent intent = new Intent(); 
      intent.setClass(Student.this, MainActivity.class); 
      startActivity(intent); 
     } 

    } 

    return true; 
} 

} 

スクロールが遅れる以外はすべてうまくいきますが、何か助けていただければ幸いです。

---

EDIT

public class AddFood extends AppCompatActivity { 

EditText edtName, edtPrice; 
Button btnChoose, btnAdd, btnList; 
CircularImageView imageView; 

final int REQUEST_CODE_GALLERY = 999; 

public static SQLiteHelper sqLiteHelper; 

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

    init(); 

    sqLiteHelper = new SQLiteHelper(this, "FoodDB.sqlite", null, 1); 

    sqLiteHelper.queryData("CREATE TABLE IF NOT EXISTS FOOD(Id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR, price VARCHAR, image BLOB)"); 

    btnChoose.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      ActivityCompat.requestPermissions(
        AddFood.this, 
        new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 
        REQUEST_CODE_GALLERY 
      ); 
     } 
    }); 

    //THIS IS WHERE I ADD 

    btnAdd.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View view) { 
      try{ 
       sqLiteHelper.insertData(
         edtName.getText().toString().trim(), 
         edtPrice.getText().toString().trim(), 
         imageViewToByte(imageView) 
       ); 
       Toast.makeText(getApplicationContext(), "Added successfully!", Toast.LENGTH_SHORT).show();     
       finish(); 
      } 
      catch (Exception e){ 
       e.printStackTrace(); 
      } 


     } 
    }); 

} 

private byte[] imageViewToByte(ImageView image) { 
    Bitmap bitmap = ((BitmapDrawable)image.getDrawable()).getBitmap(); 
    ByteArrayOutputStream stream = new ByteArrayOutputStream(); 
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); 
    byte[] byteArray = stream.toByteArray(); 
    return byteArray; 
} 

@Override 
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { 

    if(requestCode == REQUEST_CODE_GALLERY){ 
     if(grantResults.length >0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){ 
      Intent intent = new Intent(Intent.ACTION_PICK); 
      intent.setType("image/*"); 
      startActivityForResult(intent, REQUEST_CODE_GALLERY); 
     } 
     else { 
      Toast.makeText(getApplicationContext(), "You don't have permission to access file location!", Toast.LENGTH_SHORT).show(); 
     } 
     return; 
    } 

    super.onRequestPermissionsResult(requestCode, permissions, grantResults); 
} 

@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 

    if(requestCode == REQUEST_CODE_GALLERY && resultCode == RESULT_OK && data != null){ 
     Uri uri = data.getData(); 

     try { 
      InputStream inputStream = getContentResolver().openInputStream(uri); 

      Bitmap bitmap = BitmapFactory.decodeStream(inputStream); 
      imageView.setImageBitmap(bitmap); 

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

    super.onActivityResult(requestCode, resultCode, data); 
} 

private void init(){ 
    edtName = (EditText) findViewById(R.id.edtName); 
    edtPrice = (EditText) findViewById(R.id.edtPrice); 
    btnChoose = (Button) findViewById(R.id.btnChoose); 
    btnAdd = (Button) findViewById(R.id.btnAdd); 
    btnList = (Button) findViewById(R.id.btnList); 
    imageView = (CircularImageView) findViewById(R.id.imageView); 
} 

} 

Answer 1

この1 この例では、あなたが効率的にイメージをロードする必要がスクロール中に遅れを取り除くためにあなたが

public class MainActivity extends Activity { 

    public class ImageAdapter extends BaseAdapter { 

    private Context mContext; 
    ArrayList<String> itemList = new ArrayList<String>(); 

    public ImageAdapter(Context c) { 
     mContext = c; 
    } 

    void add(String path){ 
     itemList.add(path); 
    } 

    @Override 
    public int getCount() { 
    return itemList.size(); 
    } 

    @Override 
    public Object getItem(int arg0) { 
    // TODO Auto-generated method stub 
    return null; 
    } 

    @Override 
    public long getItemId(int position) { 
    // TODO Auto-generated method stub 
    return 0; 
    } 

    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
    ImageView imageView; 
     if (convertView == null) { // if it's not recycled, initialize some attributes 
      imageView = new ImageView(mContext); 
      imageView.setLayoutParams(new GridView.LayoutParams(220, 220)); 
      imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); 
      imageView.setPadding(8, 8, 8, 8); 
     } else { 
      imageView = (ImageView) convertView; 
     } 

     Bitmap bm = decodeSampledBitmapFromUri(itemList.get(position), 220, 220); 

     imageView.setImageBitmap(bm); 
     return imageView; 
    } 

    public Bitmap decodeSampledBitmapFromUri(String path, int reqWidth, int reqHeight) { 

    Bitmap bm = null; 
    // First decode with inJustDecodeBounds=true to check dimensions 
    final BitmapFactory.Options options = new BitmapFactory.Options(); 
    options.inJustDecodeBounds = true; 
    BitmapFactory.decodeFile(path, options); 

    // Calculate inSampleSize 
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight); 

    // Decode bitmap with inSampleSize set 
    options.inJustDecodeBounds = false; 
    bm = BitmapFactory.decodeFile(path, options); 

    return bm; 
    } 

    public int calculateInSampleSize(

    BitmapFactory.Options options, int reqWidth, int reqHeight) { 
    // Raw height and width of image 
    final int height = options.outHeight; 
    final int width = options.outWidth; 
    int inSampleSize = 1; 

    if (height > reqHeight || width > reqWidth) { 
    if (width > height) { 
    inSampleSize = Math.round((float)height/(float)reqHeight);  
    } else { 
    inSampleSize = Math.round((float)width/(float)reqWidth);  
    } 
    } 

    return inSampleSize;  
    } 

} 

    ImageAdapter myImageAdapter; 

@Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     GridView gridview = (GridView) findViewById(R.id.gridview); 
     myImageAdapter = new ImageAdapter(this); 
     gridview.setAdapter(myImageAdapter); 

     String ExternalStorageDirectoryPath = Environment 
      .getExternalStorageDirectory() 
      .getAbsolutePath(); 

     String targetPath = ExternalStorageDirectoryPath + "/test/"; 

     Toast.makeText(getApplicationContext(), targetPath, Toast.LENGTH_LONG).show(); 
     File targetDirector = new File(targetPath); 

     File[] files = targetDirector.listFiles(); 
     for (File file : files){ 
     myImageAdapter.add(file.getAbsolutePath()); 
     } 
    } 

} 

Answer 2

をたくさんのに役立ちますしてみてください。あなたができることは、Glideのような画像読み込みライブラリを使うことです。

ちょうど私はまた、あなたがするためにLoading Large Bitmaps Efficiently

EDIT

を読むことをお勧めライブラリをインポートし、これらの行にこの1

Glide.with(context) 
    .load(food.getImage()) 
    .into(holder.imageView); 

と

byte[] foodImage = food.getImage(); 
Bitmap bitmap = BitmapFactory.decodeByteArray(foodImage, 0, foodImage.length); 
holder.imageView.setImageBitmap(bitmap); 

を置き換えますaリサイクルの問題を解消してください（実際問題ではありませんが、リストビューの仕組みです）。写真があるかどうかチェックする必要があります。

「はい」の場合は、Glideを使用してイメージを読み込みます。それ以外の場合はnull（または選択したデフォルトのイメージ）に設定します。

if (food.getImage() != null && food.getImage().length > 0) { 
     Glide.with(context) 
       .load(food.getImage()) 
       .into(holder.imageView); 
    } 
    else { 
     holder.imageView.setImageBitmap(null); //or an image of your choice 
    }