程序包 ohos.data.orm

类 UpgradeComparator

java.lang.Object

ohos.data.orm.UpgradeComparator

所有已实现的接口:

Comparator<OrmMigration>

public class UpgradeComparator
extends Object
implements Comparator<OrmMigration>

Represents the comparator for a database upgrade.

The comparator sorts OrmMigration objects in an ascending order of the version number so that the database can be upgraded in the given order. The comparator automatically takes effect during a database upgrade.

从以下版本开始:

1

另请参阅:

DowngradeComparator

SystemCapability

SystemCapability.Data#DATA_APPDATAMGR

构造器概要

构造器

构造器	说明
UpgradeComparator()

方法概要

限定符和类型	方法	说明
int	compare(OrmMigration o1, OrmMigration o2)	Compares the upgrade sequence of two OrmMigration objects.

从接口继承的方法 java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

UpgradeComparator

public UpgradeComparator()

方法详细资料

compare

public int compare(OrmMigration o1,
                   OrmMigration o2)

Compares the upgrade sequence of two OrmMigration objects.

The OrmMigration object with an earlier start version will be upgraded before the other. If the two OrmMigration objects have the same start version, the object with an earlier end version will be upgraded before the other.

指定者:

compare 在接口中 Comparator<OrmMigration>

参数:

o1 - Indicates the first OrmMigration object.

o2 - Indicates the second OrmMigration object.

返回:

Returns -1 if the first object will be upgraded before the second object; returns 0 if the two objects will be upgraded at the same time; returns 1 if the second object will be upgraded before the first object.

从以下版本开始:

1