When onUpgrade is called in Android?

When the superclass constructor runs, it compares the version of the stored SQLite . db file against the version you passed as a parameter. If they differ, onUpgrade() gets called.

What is onUpgrade in Android?

Android SQLite onUpgrade() method SQLiteOpenHelper is a helper class to manage database creation and version management. In this class, the onUpgrade() method is responsible for upgrading the database when you make changes to the schema. For each database version, the specific changes you made have to be applied.

What is SQLiteOpenHelper in Android?

android.database.sqlite.SQLiteOpenHelper. A helper class to manage database creation and version management. You create a subclass implementing onCreate , onUpgrade and optionally onOpen , and this class takes care of opening the database if it exists, creating it if it does not, and upgrading it as necessary.

What is getReadableDatabase() in Android?

getReadableDatabase() Create and/or open a database. SQLiteDatabase. getWritableDatabase() Create and/or open a database that will be used for reading and writing.

Which features are considered while creating android application?

Keep It Simple!

• Several Platforms and Devices. Conventional desktop and laptop PCs are Windows-based with a standard screen size, components, and form factor.
• Screen size.
• User Interface.
• Screen Density.
• Integration with phone functions.
• Limited CPU/Memory/Battery Resources.

What is ContentValues?

ContentValues is a maplike class that matches a value to a String key. It contains multiple overloaded put methods that enforce type safety. Here is a list of the put methods supported by ContentValues: void put(String key, Byte value) void put(String key, Integer value)

What is onCreate method in Android?

onCreate is used to start an activity. super is used to call the parent class constructor. setContentView is used to set the xml.

Why SQLite is used in Android?

SQLite is an open-source relational database i.e. used to perform database operations on android devices such as storing, manipulating or retrieving persistent data from the database. It is embedded in android bydefault. So, there is no need to perform any database setup or administration task.

What is a cursor in Android?

A Cursor represents the result of a query and basically points to one row of the query result. This way Android can buffer the query results efficiently; as it does not have to load all data into memory. To get the number of elements of the resulting query use the getCount() method.

What is difference between ContentValues and cursor?

Q 12 – What is the difference between content values and cursor in android SQlite? A – Content values are key pair values, which are updated or inserted in the database B – Cursor is used to store the temporary result. C – A & B D – Cursor is used to store data permanently.

When to use onupgrade and oncreate in Java?

onUpgrade () is only called when the database file exists but the stored version number is lower than requested in constructor. The onUpgrade () should update the table schema to the requested version. When changing the table schema in code ( onCreate () ), you should make sure the database is updated.

How does SQLite onupgrade ( ) work in Android?

Now the app will iterate over the update statements and run any that are needed. No matter what previous version was and regardless of what more recent version they upgrade to, the app will run the proper statements to take the app from the older schema to the properly upgraded one.

Is the Android emulator compatible with Android 8.1?

To work with Android 8.1 (API level 27) and higher system images, an attached webcam must have the capability to capture 720p frames. The Android Emulator was deprecated in June 2019 for 32-bit Windows systems.

When is sqliteopenhelper oncreate ( ) / onupgrade ( ) invoked?

SQLiteOpenHelper onCreate () and onUpgrade () callbacks are invoked when the database is actually opened, for example by a call to getWritableDatabase (). The database is not opened when the database helper object itself is created. SQLiteOpenHelper versions the database files. The version number is the int argument passed to the constructor.