程序包 ohos.data.orm

类 DowngradeComparator

java.lang.Object

ohos.data.orm.DowngradeComparator

所有已实现的接口:

Comparator<OrmMigration>

public class DowngradeComparator
extends Object
implements Comparator<OrmMigration>

Represents the comparator for a database downgrade.

The comparator sorts OrmMigration objects in a descending order of the version number so that the database can be downgraded in the given order. The comparator automatically takes effect during a database downgrade.

从以下版本开始:

1

另请参阅:

UpgradeComparator

SystemCapability

SystemCapability.Data#DATA_APPDATAMGR

构造器概要

构造器

构造器	说明
DowngradeComparator()

方法概要

限定符和类型	方法	说明
int	compare(OrmMigration o1, OrmMigration o2)	Compares the downgrade 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

DowngradeComparator

public DowngradeComparator()

方法详细资料

compare

public int compare(OrmMigration o1,
                   OrmMigration o2)

Compares the downgrade sequence of two OrmMigration objects.

The OrmMigration object with a later start version will be downgraded before the other. If the two OrmMigration objects have the same start version, the object with a later end version will be downgraded 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 downgraded before the second object; returns 0 if the two objects will be downgraded at the same time; returns 1 if the second object will be downgraded before the first object.

从以下版本开始:

1