added in version 1.1.0
belongs to Maven artifact android.arch.persistence.room:runtime:1.1.0-beta2

Summary: Fields | Ctors | Methods | Inherited Methods

Migration

The android.arch Architecture Components packages are no longer maintained. They have been superseded by the corresponding androidx.* packages. See androidx.room.migration.Migration instead.

public abstract class Migration
extends Object

java.lang.Object
↳	android.arch.persistence.room.migration.Migration

---

Base class for a database migration.

Each migration can move between 2 versions that are defined by startVersion and endVersion.

A migration can handle more than 1 version (e.g. if you have a faster path to choose when going version 3 to 5 without going to version 4). If Room opens a database at version 3 and latest version is >= 5, Room will use the migration object that can migrate from 3 to 5 instead of 3 to 4 and 4 to 5.

If there are not enough migrations provided to move from the current version to the latest version, Room will clear the database and recreate so even if you have no changes between 2 versions, you should still provide a Migration object to the builder.

Summary

Fields
public final int	endVersion
public final int	startVersion

Public constructors
Migration(int startVersion, int endVersion) Creates a new migration between startVersion and endVersion.

Public methods
abstract void	migrate(SupportSQLiteDatabase database) Should run the necessary migrations.

Inherited methods
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait(long arg0, int arg1) final void wait(long arg0) final void wait()

Fields

endVersion

added in version 1.1.0

int endVersion

startVersion

added in version 1.1.0

int startVersion

Public constructors

Migration

added in version 1.1.0

Migration (int startVersion, 
                int endVersion)

Creates a new migration between startVersion and endVersion.

Parameters
startVersion	int: The start version of the database.
endVersion	int: The end version of the database after this migration is applied.

Public methods

migrate

added in version 1.1.0

void migrate (SupportSQLiteDatabase database)

Should run the necessary migrations.

This class cannot access any generated Dao in this method.

This method is already called inside a transaction and that transaction might actually be a composite transaction of all necessary Migrations.

Parameters
database	SupportSQLiteDatabase: The database instance

• Classes

  • Migration