Storage Mechanisms in Android Application-1

#Tutorial 1 (Creating Database and table)
Android provides several options to store persistent data. Some of them are Internal Storage, External Storage, SQLite Database and Shared Preferences. In this tutorial, i will discuss about SQLite Database to store persistent data.

Important Points:

• SQLite is an open source database
• SQLite supports standard relational database features
• Each android device comes up with built in SQLite database implementation
• Data stored in database remains private to other applications
• To create SQLite database, you need to create a subclass of SQLiteOpenHelper class.

Let's us go for a simple demo inheriting SQLiteOpenHelper class to create a database and a table inside it. To start with, create a new android application project and assign the names as per IDE defaults. I assume that, the name of the Activity is MainActivity and layout_name is activity_main.xml.

activity_main.xml-----

<LinearLayout

xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_height="fill_parent"

android:layout_width="fill_parent"

android:orientation="vertical">

<EditText

android:id="@+id/editText1"

android:layout_height="wrap_content"

android:layout_width="fill_parent"

android:hint="Enter Book Name"/>

<EditText

android:id="@+id/editText2"

android:layout_height="wrap_content"

android:layout_width="fill_parent"

android:hint="Enter Book Author"/>

<Button

android:id="@+id/submit"

android:layout_height="wrap_content"

android:layout_width="fill_parent"

android:text="Submit"/>

</LinearLayout>

MainActivity.java---

public class MainActivity extends Activity

{

DatabaseHelper myDb;

@Override

public void onCreate(Bundle savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

myDb=new DatabaseHelper(this);

}

}

DatabaseHelper.java---

public class DatabaseHelper extends SQLiteOpenHelper

{

public static final String DATABASE_NAME="Library.db";

public static final String TABLE_NAME="Books";

// constructor with one argument

public DatabaseHelper(Context context)

{

super(context,DATABASE_NAME,null,1);

SQLiteDatabase db=this.getWritableDatabase();

}

// implementing default methods

@Override

public void onCreate(SQLiteDatabase db)

{

db.exexSQL("create table"+TABLE_NAME+ "(id number primary key autoincrement , book_name text, book_author text)");

}

@Override

public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion)

{

db.execSQL("DROP TABLE IF EXISTS"+TABLE_NAME);

onCreate(db);

}

}

So running this application, will only create the database and the table, To learn how to insert data inside the table follow the next series of this tutorial.