私のデータベースファイルをアプリケーションにアクセスできない

Question

データフォーム資産フォルダにアクセスする必要があるアプリケーションを作成しました。私は、データベースを開くために、データベースのヘルパークラスを使用していますが、私は、データベースにアクセスすることができませんし、私は私のコード

public class DidUMean extends Activity { 
DataBaseHelper myDbHelper; 
public SQLiteDatabase mydatabase; 
String searchWord; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 

    super.onCreate(savedInstanceState); 
    setContentView(R.layout.didumean); 

    myDbHelper = new DataBaseHelper(DidUMean.this); 

    didYouMean(searchWord); 

} 

public void didYouMean(String searchWord) { 
    myDbHelper.openDataBase(); 
    mydatabase = myDbHelper.getWritableDatabase(); 
    Cursor cc = mydatabase.rawQuery("SELECT COUNT(*) FROM tblVocab", 
      null); 
    try { 
     if (cc.getCount() == 0) { 
      System.out.println("----> "+cc.getCount()); 
     } 
    } catch (SQLException sqle) { 
     System.out.println(sqle); 
     throw sqle; 
    } finally { 
     myDbHelper.close(); 
    } 
} 
} 

私はLogcatに次のエラーを取得していますを入れています。

03-28 15:12:48.945: ERROR/AndroidRuntime(1995): FATAL EXCEPTION: main 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.lauruss.verb2verbe/com.lauruss.verb2verbe.DidUMean}: android.database.sqlite.SQLiteException: unable to open database file 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.os.Handler.dispatchMessage(Handler.java:99) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.os.Looper.loop(Looper.java:123) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at java.lang.reflect.Method.invokeNative(Native Method) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at java.lang.reflect.Method.invoke(Method.java:521) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at dalvik.system.NativeStart.main(Native Method) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995): Caused by: android.database.sqlite.SQLiteException: unable to open database file 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.database.sqlite.SQLiteDatabase.dbopen(Native Method) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.database.sqlite.SQLiteDatabase.<init>(SQLiteDatabase.java:1812) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:817) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at com.lauruss.verb2verbe.DataBaseHelper.openDataBase(DataBaseHelper.java:109) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at com.lauruss.verb2verbe.DidUMean.didYouMean(DidUMean.java:27) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at com.lauruss.verb2verbe.DidUMean.onCreate(DidUMean.java:22) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
03-28 15:12:48.945: ERROR/AndroidRuntime(1995):  ... 11 more 

Answer 1

public class DataBaseHelper extends SQLiteOpenHelper{ 

//The Android's default system path of your application database. 
private static String DB_PATH = "/data/data/com.lauruss.verb2verbe/databases/"; 
private static String DB_NAME = "v2v.db"; 
private SQLiteDatabase myDataBase; 
private final Context myContext; 

/** 
* Constructor 
* Takes and keeps a reference of the passed context in order to access to the application assets and resources. 
* @param context 
*/ 
public DataBaseHelper(Context context) { 

    super(context, DB_NAME, null, 1); 
    this.myContext = context; 
} 

このdatabasehelperクラスのオブジェクトを作成する必要があります*システム上に空のデータベースを作成し、あなたにそれを書き換え独自のデータベース。 * */ ます。public void createDataBaseは（）** DataBaseHelper **のためにIOException {

boolean dbExist = checkDataBase(); 

    if(dbExist){ 
     Log.d("Rikta", "Database Exist"); 
     //do nothing - database already exist 

     }else{ 
      Log.d("Rikta", "Database Does Not Exist"); 
      this.getReadableDatabase(); 
     try { 
      copyDataBase(); 
     } catch (IOException e) { 
      throw new Error("Error copying database"); 
     } 
    } 
} 
/** 
* Check if the database already exist to avoid re-copying the file each time you open the application. 
* @return true if it exists, false if it doesn't 
*/ 
private boolean checkDataBase(){ 
    SQLiteDatabase checkDB = null; 
    try{ 
     String myPath = DB_PATH + DB_NAME; 
     Log.d("Maulik", myPath); 
    // checkDB = SQLiteDatabase.openOrCreateDatabase(myPath, null); 
     checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 
    }catch(SQLiteException e){ 
     //database does't exist yet. 
    } 
    if(checkDB != null){ 
     checkDB.close(); 
    } 
    return checkDB != null ? true : false; 
} 

/** 
* Copies your database from your local assets-folder to the just created empty database in the 
* system folder, from where it can be accessed and handled. 
* This is done by transfering bytestream. 
* */ 
private void copyDataBase() throws IOException{ 


    //Open your local db as the input stream 
    InputStream myInput = myContext.getAssets().open(DB_NAME); 

    // Path to the just created empty db 
    String outFileName = DB_PATH + DB_NAME; 
    Log.d("copyDataBase", outFileName); 
    //Open the empty db as the output stream 
    OutputStream myOutput = new FileOutputStream(outFileName); 

    //transfer bytes from the inputfile to the outputfile 
    byte[] buffer = new byte[1024]; 
    int length; 
    while ((length = myInput.read(buffer))>0){ 
     myOutput.write(buffer, 0, length); 
    } 
    //Close the streams 
    myOutput.flush(); 
    myOutput.close(); 
    myInput.close(); 
} 
public void openDataBase() throws SQLException{ 

    //Open the database 
    String myPath = DB_PATH + DB_NAME; 
    Log.d("openDatabase", myPath); 
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.CREATE_IF_NECESSARY); 
} 

@Override 
public synchronized void close() { 
     if(myDataBase != null) 
      myDataBase.close(); 
     super.close(); 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
} 

    // Add your public helper methods to access and get content from the database. 
    // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy 
    // to you to create adapters for your views. 

}

Answer 2

あなたはそれが存在、あなたのデータベースを確認したい場合は...
ファイルエクスプローラデータ\データ\パッケージ名\データベース\データベースName.db

は、データベースのためのあなたのクラスを作成します...

public class MySQLiteHelper extends SQLiteOpenHelper 

そして...方法に従い

public MySQLiteHelper open() throws SQLException 
{ 
    db = this.getWritableDatabase(); 
    return this; 
} 

public MySQLiteHelper(Context context) 
{ 
    super(context, DATABASE_NAME, null, DATABASE_VERSION); 

} 


@Override 
public void onCreate(SQLiteDatabase database) 
{ 

    database.execSQL(DATABASE_CREATE); 
    } 

@Override 
public void onUpgrade(SQLiteDatabase database, int oldVersion, int newVersion) { 
    // TODO Auto-generated method stub 
    Log.w(MySQLiteHelper.class.getName(), "Upgrading database from version " 
      + oldVersion + " to " + newVersion 
      + ", which will destroy all old data"); 
    database.execSQL("DROP TABLE IF EXISTS " + TABLE_SUBJECT); 
      } 

を書きます

次に、あなたがあなたのactivity.javaに/ **

public class AddQuestionActivity extends Activity 
db=new MySQLiteHelper(getBaseContext()); 
        db.getWritableDatabase(); 

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