org.opencms.file.collectors
Class CmsDateResourceComparator

java.lang.Object
  org.opencms.file.collectors.CmsDateResourceComparator

All Implemented Interfaces:

java.util.Comparator

public class CmsDateResourceComparator
extends java.lang.Object
implements java.util.Comparator

Comparator for sorting resource objects based on dates.

The comparator can be configured to use any date based on resource attributes or properties. The user must in the constructor CmsDateResourceComparator(CmsObject, List, boolean) provide a list of one or more date identifiers that should be checked, in the order they should be checked. This list of dates identifiers must be Strings which tell the comparator which dates to use. The first valid date identifier that is found for a resource is used as date for comparing this resource to other resources.

The following date identifiers can be used to access the corresponding value of a CmsResource:

• "dateCreated", which means CmsResource.getDateCreated().
• "dateLastModified", which means CmsResource.getDateLastModified().
• "dateContent", which means CmsResource.getDateContent().
• "dateReleased", which means CmsResource.getDateReleased().
• "dateExpired", which means CmsResource.getDateExpired().
• Anything else will be treated as property name, so it will be attempted to read a property with that name from the resource, and convert that value to a long. Should this fail for any reason, the next entry from the list of dates will be processed.

• If no match is found at all, CmsResource.getDateCreated() is used as default.

Serves as Comparator for resources and as comparator key for the resource at the same time. Uses lazy initializing of comparator keys for a resource.

Since:

6.0.0

Version:

$Revision: 1.4 $

Author:

Alexander Kandzior

Field Summary

static java.util.List

DATE_ATTRIBUTES_LIST Possible keywords to read dates from the resource attributes in a List.

Constructor Summary

CmsDateResourceComparator(CmsObject cms, java.util.List dateIdentifiers, boolean asc)
Creates a new instance of this comparator key.

Method Summary

static long	calculateDate(CmsObject cms, CmsResource resource, java.util.List dateIdentifiers, long defaultValue) Calculates the date to use for comparison of this resource based on the given date identifiers.
int	compare(java.lang.Object arg0, java.lang.Object arg1)
long	getDate() Returns the date of this resource comparator key.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Field Detail

DATE_ATTRIBUTES_LIST

public static final java.util.List DATE_ATTRIBUTES_LIST

Possible keywords to read dates from the resource attributes in a List.

Constructor Detail

CmsDateResourceComparator

public CmsDateResourceComparator(CmsObject cms,
                                 java.util.List dateIdentifiers,
                                 boolean asc)

Creates a new instance of this comparator key.

Parameters:

cms - the current OpenCms user context

dateIdentifiers - the names of the dates to check

asc - if true, the date sort order is ascending, otherwise descending

Method Detail

calculateDate

public static long calculateDate(CmsObject cms,
                                 CmsResource resource,
                                 java.util.List dateIdentifiers,
                                 long defaultValue)

Calculates the date to use for comparison of this resource based on the given date identifiers.

Parameters:

cms - the current OpenCms user context

resource - the resource to create the key for

dateIdentifiers - the date identifiers to use for selecting the date

defaultValue - the default value to use in case no value can be calculated

Returns:

the calculated date

See Also:

for a description about how the date identifieres are used

compare

public int compare(java.lang.Object arg0,
                   java.lang.Object arg1)

Specified by:

compare in interface java.util.Comparator

See Also:

Comparator.compare(java.lang.Object, java.lang.Object)

getDate

public long getDate()

Returns the date of this resource comparator key.

Returns:

the date of this resource comparator key