android.database.sqlite.SQLiteOpenHelper
Summary
Public Constructors
Public Methods
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
Details
Public Constructors
Create a helper object to create, open, and/or manage a database.
The database is not actually created or opened until one of
getWritableDatabase() or
getReadableDatabase() is called.
Parameters
context
| to use to open or create the database |
name
| of the database file, or null for an in-memory database |
factory
| to use for creating cursor objects, or null for the default |
version
| number of the database (starting at 1); if the database is older,
onUpgrade(SQLiteDatabase, int, int) will be used to upgrade the database
|
Public Methods
public
synchronized
void
close()
Close any open database object.
public
synchronized
SQLiteDatabase
getReadableDatabase()
Create and/or open a database. This will be the same object returned by
getWritableDatabase() unless some problem, such as a full disk,
requires the database to be opened read-only. In that case, a read-only
database object will be returned. If the problem is fixed, a future call
to
getWritableDatabase() may succeed, in which case the read-only
database object will be closed and the read/write object will be returned
in the future.
public
synchronized
SQLiteDatabase
getWritableDatabase()
Create and/or open a database that will be used for reading and writing.
Once opened successfully, the database is cached, so you can call this
method every time you need to write to the database. Make sure to call
close() when you no longer need it.
Errors such as bad permissions or a full disk may cause this operation
to fail, but future attempts may succeed if the problem is fixed.
Returns
- a read/write database object valid until close() is called
public
abstract
void
onCreate(SQLiteDatabase db)
Called when the database is created for the first time. This is where the
creation of tables and the initial population of the tables should happen.
Called when the database has been opened.
Override method should check
isReadOnly() before
updating the database.
public
abstract
void
onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
Called when the database needs to be upgraded. The implementation
should use this method to drop tables, add tables, or do anything else it
needs to upgrade to the new schema version.
The SQLite ALTER TABLE documentation can be found
here. If you add new columns
you can use ALTER TABLE to insert them into a live table. If you rename or remove columns
you can use ALTER TABLE to rename the old table, then create the new table and then
populate the new table with the contents of the old table.
Parameters
db
| The database. |
oldVersion
| The old database version. |
newVersion
| The new database version.
|