Databases in Android Application

Objectives
 Know more about SQLite.
 Understand the process on how to create
database in an Android application using SQLite.
 Use SQLite commands.
 Enhance Android programming skills by
incorporating database in an Android app.

Know More About SQLite.
 SQLite is an Open Source database that supports
standard relational database features like SQL
syntax, transactions and prepared statements.
 The database requires limited memory at
runtime (approx. 250 Kbyte)
 SQLite supports the data types TEXT (similar to
String in Java), INTEGER (similar to long in Java)
and REAL (similar to double in Java).

 Uses a wrapper class, SQLiteOpenHelper which
offers three basic API methods to interact with the
database:
 onCreate(SQLiteDatabase db), called when the
database is created for the first time.
 onOpen(SQLiteDatabase db), called when the database
has been opened.
 onUpgrade(SQLiteDatabase db, int oldVersion, int
newVersion), called when the database needs to be
upgraded.

 The “Lite” in SQLite does not refer to its
capabilities. Rather, SQLite is lightweight when it
comes to setup complexity, administrative
overhead, and resource usage.
 Characteristics:
 Server less
 Zero Configuration
 Self-Contained
 Full-featured

Creating Database in an
Android App using SQLite
1. Design your database.
Books
Id Title Author
1 Android Database Henry Williams
2 Philippine History Jose Natividad

2. Create a new Android
Application project and
design your UI.

3. Add a class in the project that extends the
SQLOpenHelper wrapper class.

4.Doing so, will let you import necessary packages:
5. Then add the database name and the database
version.

6. Add the constructor

7. Add these two API methods:

Adding a Record to the
Database
1. To add a record, you need to create a method
for that, but declare variables first:

Adding a Record to the
Database
2. Add the addBook method, with this you need
to import ContentValues

Searching and Retrieving Data
from the Database
1. To search and retrieve data, you will have to
use Cursor class.

Implementing Database
1. On the MainActivity, add a method for getting user
input and adding it to the database

2. Add another method, this time is searching
for a book’s author based on the input title.

3. Set onClick on the xml properties of the Add and
Search buttons.
4. Run your app, fix bugs for errors. Add and search
for the ff contents:
Title Author
Android Database Henry Williams
Philippine History Jose Natividad

Laboratory Exercise:
1. Open your PC, register to NetSupport.
2. Open Exercise4 from your Desktop.
3. Read Exercise4 and follow the instructions
carefully.
4. Notify your instructor if any problems, or if done.

Updating Data
public int updateBook(String title, String author) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(key_title, title);
values.put(key_author, author);
int i = db.update(tblName, //table
values, // column/value
"title=?", // selections
new String[] { String.valueOf(title) }); //selection args
db.close();
return i;
}

public void updateBookClick(View v){
MySQLiteHelper db=new MySQLiteHelper(this);
EditText txtTitle=(EditText) findViewById(R.id.editText1);
EditText txtAuthor=(EditText) findViewById(R.id.editText2);
if ((txtTitle.getText().toString()).equalsIgnoreCase(""))
Toast.makeText(getApplicationContext(), "Invalid, null field.",
Toast.LENGTH_SHORT).show();
else {
int i= db.updateBook(txtTitle.getText().toString(), txtAuthor.getText().toString());
Toast.makeText(getApplicationContext(), i + " updated",
txtTitle.setText("");
txtAuthor.setText("");
}
}

Deleting Data
public void deleteBook(String title) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(tblName, "title=?", new String[] { String.valueOf(title)
});
db.close();
}

public void deleteBookClick(View v){
MySQLiteHelper db=new MySQLiteHelper(this);
EditText txtTitle=(EditText) findViewById(R.id.editText1);
EditText txtAuthor=(EditText) findViewById(R.id.editText2);
if ((txtTitle.getText().toString()).equalsIgnoreCase(""))
Toast.makeText(getApplicationContext(), "Invalid, null field.",
else {
db.deleteBook(txtTitle.getText().toString());
Toast.makeText(getApplicationContext(), "Book deleted",
txtTitle.setText("");
txtAuthor.setText("");
}
}

Activity Life Cycle
 Resumed - In this state, the activity is in the foreground and
the user can interact with it. (Also sometimes referred to as the
"running" state.)
 Paused - In this state, the activity is partially obscured by
another activity—the other activity that's in the foreground is
semi-transparent or doesn't cover the entire screen. The
paused activity does not receive user input and cannot
execute any code.
 Stopped - In this state, the activity is completely hidden and
not visible to the user; it is considered to be in the background.
While stopped, the activity instance and all its state
information such as member variables is retained, but it
cannot execute any code.

Activity Life Cycle
 The other states (Created and Started) are
transient and the system quickly moves from
them to the next state by calling the next
lifecycle callback method.
 That is, after the system calls onCreate(), it
quickly calls onStart(), which is quickly
followed by onResume().

protected void onStop() {
super.onStop();
ContentValues values = new ContentValues();
values.put(NotePad.Notes.COLUMN_NAME_NOTE,
getCurrentNoteText());
values.put(NotePad.Notes.COLUMN_NAME_TITLE,
getCurrentNoteTitle());
getContentResolver().update(
mUri,
values,
null,
null
}
}

Databases in Android Application

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