K.Cvetanovska K.Cvetanovska - 5 months ago 29
Android Question

How to access an existing .db file in Android?

I cannot seem to access my existing .db file in Android. I have copied the file Zones.db in \MyApp\app\src\main\assets and I have created a DatabaseHelper class, that looks like this:

public class DatabaseHelper extends SQLiteOpenHelper {

//The Android's default system path of your application database.
String DB_PATH =null;

private static String DB_NAME = "Zones";

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;
DB_PATH="/data/data/"+context.getPackageName()+"/"+"databases/";
}

/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException{

boolean dbExist = checkDataBase();

if(dbExist){
//do nothing - database already exist
}else{

//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();

try {
//<div style="display:none"></div>
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;
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;

//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;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}

@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) {
}

//return cursor
public Cursor query(String table,String[] columns, String selection,String[] selectionArgs,String groupBy,String having,String orderBy){
return myDataBase.query("Zones", null, null, null, null, null, null);
}


and a MainActivity class that looks like this:

public class MainActivity extends Activity {
Cursor c = null;

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

DatabaseHelper myDbHelper = new DatabaseHelper(MainActivity.this);

try
{
myDbHelper.createDataBase();
}
catch (IOException ioe)
{
throw new Error("Unable to create database");
}

myDbHelper.openDataBase();

Toast.makeText(MainActivity.this, "Success", Toast.LENGTH_SHORT).show();

c = myDbHelper.query("EMP_TABLE", null, "_id=3", null, null,null, null);

if(c.moveToFirst())
{
Toast.makeText(MainActivity.this,
"_id: " + c.getString(0) + "\n" +
"ZONE_LETTER: " + c.getString(1) + "\n" +
"ZONE_NUMBER: " + c.getString(2) + "\n" +
"ZONE_TIME: " + c.getString(3) + "\n" +
"ZONE_PRICE: " + c.getString(4) + "\n" +
"PHONE_NUMBER: " + c.getString(5) + "\n" +
"COMPANY: " + c.getString(6),
Toast.LENGTH_LONG).show();
}
}


When I run the app I get a no such table error saying that it cannot find the Zones table in the Zones database. Does anyone know how to fix this?

Answer

Try This code it's work Perfectly just change your table name and Package name

public class SqlLiteDataBaseHelper extends SQLiteOpenHelper{
    private static final String TAG = SqlLiteDataBaseHelper.class.getSimpleName();
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_PATH = "/data/data/YOUR PACKAGE NAME/databases/";
    private static final String DATABASE_NAME = "test1.sqlite";
    private static final String TABLE_NAME = "Student";
    private static final String COL_Name = "Name";
    private static final String COL_ROLL_NO ="RollNo";
    private Context context;
    private SQLiteDatabase db;

    public SqlLiteDataBaseHelper(Context context) {
        super(context,DATABASE_NAME,null,DATABASE_VERSION);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }


    //This method is just retuning total no of recode in your table Getting single contact count
    public int  getDataCount() {

        String userRollNo = null;

        String query = "SELECT * FROM " + TABLE_NAME ;

        Cursor cursor = db.rawQuery(query, null);

        return cursor.getCount();
    }




    public void openDataBase () throws SQLException{
        String path = DATABASE_PATH+DATABASE_NAME;
        db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS | SQLiteDatabase.CREATE_IF_NECESSARY);
    }

    public void CopyDataBaseFromAsset() throws IOException {
        InputStream in  = context.getAssets().open(DATABASE_NAME);
        Log.e("sample", "Starting copying");
        String outputFileName = DATABASE_PATH+DATABASE_NAME;
        File databaseFile = new File( "/data/data/YOUR PACKAGE NAME/databases");
        // check if databases folder exists, if not create one and its subfolders
        if (!databaseFile.exists()){
            databaseFile.mkdir();
        }

        OutputStream out = new FileOutputStream(outputFileName);

        byte[] buffer = new byte[1024];
        int length;


        while ((length = in.read(buffer))>0){
            out.write(buffer,0,length);
        }
        Log.e("sample", "Completed" );
        out.flush();
        out.close();
        in.close();

    }

    public void deleteDb() {
        File file = new File(DATABASE_PATH);
        if(file.exists()) {
            file.delete();
            Log.d(TAG, "Database deleted.");
        }
    }
    public boolean checkDataBase() {
        boolean checkDB = false;
        try {
            File file = new File(DATABASE_PATH);
            checkDB = file.exists();
        } catch(SQLiteException e) {
            Log.d(TAG, e.getMessage());
        }
        return checkDB;
    }
}

To use in your actvity

sqlLiteDataBaseHelper = new SqlLiteDataBaseHelper(this);


        try {

            if(sqlLiteDataBaseHelper.checkDataBase()){

                Log.e(TAG,"Data Base Already Exists");

            }else {

                sqlLiteDataBaseHelper.CopyDataBaseFromAsset();

            }

        }catch (Exception e){
            e.printStackTrace();
        }
        try {

            sqlLiteDataBaseHelper.openDataBase();
             // after open data  base u can read write data base 

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