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Android Database Tutorial
The Android platform offers a variety of storage options you can use in your apps. If you need a structured data source, you can use an SQLite database. If you have used any SQL database in the past, such as MySQL, you will be able to use SQLite easily as you will already be accustomed to the principles and syntax involved. If you have no experience using SQL or scripting with databases, you can still pick up the essentials of using SQLite databases in your Android projects. 

In this tutorial we will work through the process of using an SQLite database in Android. We will create a simple note-keeping app in which the user can add, view and delete notes. The notes will be displayed in a list, with a button to add new notes and the option to delete notes on clicking each one in the list. The tutorial will take you through the procedure of basic SQLite database implementation in Android, so you will be able to reuse the skills and techniques involved in other applications. Here is a preview of the app: 




For a broader overview of using SQLite in your Android apps check out the invariably excellent Vogella site, particularly this tutorial: Android SQLite database and content provider- in this tutorial we will use a similar algorithm but will simplify some of the elements and add a little more explanation of the steps involved. 

Project Setup 
Create a new Android project. You will need a blank main Activity and layout. We will also be using three additional Java classes, but their content will be relatively simple so don't worry if you have only created simple Android projects so far, this one is accessible to beginners. 

Layout 
Open your app layout file. We are going to use a ListActivity for the app, which requires a layout containing a ListView with a particular ID. Using a setup like this lets you take advantage of some of the automated aspects of the Android platform, reducing the amount of functionality you have to implement yourself. Essentially we will be using the ListActivity andListView to provide an interface to the database. Enter the following layout:
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
 xmlns:tools="http://schemas.android.com/tools"  
 android:layout_width="match_parent"  
 android:layout_height="match_parent"  
 android:background="#FF3366CC"  
 android:orientation="vertical"  
 tools:context=".MainActivity" >  
  
 <Button  
  android:id="@+id/new_btn"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_gravity="center"  
  android:layout_margin="5dp"  
  android:onClick="addNewNote"  
  android:text="New"  
  android:textColor="#FFFFFFFF" />  
  
 <ListView  
  android:id="@android:id/list"  
  android:layout_width="fill_parent"  
  android:layout_height="wrap_content"  
  android:layout_margin="10dp"  
  android:background="#FFFFEE66" />  
  
</LinearLayout>  
The layout is simple, it includes a button for the user to add a new note and a ListViewdisplaying the existing notes. We specify a method to execute on clicking the button so will include it in our main Activity class later. The Java code will handle the processing required for displaying the database content in the ListView. For now, add the following import statements to your main Activity:
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import java.util.List;  
  
import android.app.AlertDialog;  
import android.app.ListActivity;  
import android.content.DialogInterface;  
import android.view.Menu;  
import android.view.View;  
import android.widget.AdapterView;  
import android.widget.AdapterView.OnItemClickListener;  
import android.widget.ArrayAdapter;  
import android.widget.EditText;  
import android.widget.ListView;  
Make the class extend ListActivity for displaying the notes in a list:
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public class MainActivity extends ListActivity  
Helper Classes 
Let's add all of the classes to the app. To use the SQLite database we need anSQLiteOpenHelper class, so add a new class to your application package, naming it "MyDataHelper" and choosing SQLiteOpenHelper is its superclass - the opening line of the declaration should appear as follows:
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public class MyDataHelper extends SQLiteOpenHelper  
Your class will need the following import statements:
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import android.content.Context;  
import android.database.sqlite.SQLiteDatabase;  
import android.database.sqlite.SQLiteOpenHelper;  
import android.provider.BaseColumns;  
We will implement the class details soon. We are also going to use a class dedicated to managing the database connection rather than doing this from the main Activity, so add another new class to your package, naming it "NoteManager". Add the following imports to the class:
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import java.util.ArrayList;  
import java.util.List;  
  
import android.content.ContentValues;  
import android.content.Context;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
import android.database.sqlite.SQLiteOpenHelper;  
The final class we need is to model the notes themselves, so add another new class, naming it "Note". Let's implement this class now. Use the following declaration:
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public class Note {  
  
 private long noteID;  
 private String noteText;  
  
 public void setNoteText(String userText){  
  noteText=userText;  
 }  
 public String getNoteText(){  
  return noteText;  
 }  
 public void setNoteID(long newID){  
  noteID=newID;  
 }  
 public long getNoteID(){  
  return noteID;  
 }  
 @Override  
 public String toString(){  
  return noteText;  
 }  
  
}  
Each note will consist of a unique ID number and a text string representing the note content. These two data items are what we will add to the database for each note, so the Note class models the same data, with standard get and set methods we will use elsewhere in the app code. We implement the toString method because it will be used by Android when displaying the notes in the ListView.