samedi 10 octobre 2015

How to Write MainActivity for MYDBHandler.? So it Shows data in TextView

//This My MYDBHandler File

public class MyDBHandler extends SQLiteOpenHelper {

private static String DB_PATH = "/data/data/http://ift.tt/1WUsOXk";
private static String DB_NAME = "question";
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.

public MyDBHandler(Context context) {
    super(context, DB_NAME, null,1);
    this.myContext = context;
    this.createDatabase();
}

Creates a empty database on the system and rewrites it with your own database.

public void createDatabase() {
    try {
        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 application so we are gonna be able to overwrite that database with our database.

            this.getReadableDatabase();
            copyDataBase();
        }
    }
    catch (Exception e) {

    }
}

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(){

    try{
        //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();
    }
    catch (Exception e) {
        //catch exception
    }
}

public SQLiteDatabase openDataBase() throws SQLException{

    String myPath = DB_PATH + DB_NAME;
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    return myDataBase;

}

@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) {
}

}

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