SQLiteAssetHelper擴展返回null

Question

我從我的DatabaseHandler中收到NullPointerException。

這裏是我的數據庫處理器：

public class DatabaseHandler extends SQLiteAssetHelper { 

    private static final int DATABASE_VERSION = 1; 
    private static final String DATABASE_NAME = "carsGrid", 
      TABLE_CARS = "cars ", 
      KEY_ID = "id", 
      KEY_POSTCODE = "postcode", 
      KEY_ADDRESS = "address", 
      KEY_IMAGE = "image"; 


     public DatabaseHandler(Context context) { 
      //super(context, DATABASE_NAME, null, DATABASE_VERSION); 
      super(context, DATABASE_NAME, context.getExternalFilesDir(null).getAbsolutePath(), null, DATABASE_VERSION); 
     } 
} 

MyActivity.java：

// Initiate Database 
      DatabaseHandler db = new DatabaseHandler(this); // "this" refer to the context 

我有一種感覺這是導致問題的背景下，但我：這是報告錯誤

線我不知道上下文應該是什麼。我剛剛從SQLiteOpenHelper

改變

錯誤上一行：

public DatabaseHandler(Context context) { 
    //super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    super(context, DATABASE_NAME, context.getExternalFilesDir(null).getAbsolutePath(), null, DATABASE_VERSION); 
} 

Answer 1

在Activity

DatabaseHandler db = new DatabaseHandler(getApplicationContext()); 

或

DatabaseHandler db = new DatabaseHandler(YourActivity.this);