com.tomgibara.pronto.config.source
Class LastModifiedCalculator

java.lang.Object
  com.tomgibara.pronto.config.source.LastModifiedCalculator

public final class LastModifiedCalculator
extends java.lang.Object

Instances of this class can compute accurate values for lastModified from property maps alone. The property maps supplied to these objects are not modified and are copied if their values need to be recorded by this object. The copies made in this way are available via the getProperties() method.

Author:

Tom Gibara

Constructor Summary

LastModifiedCalculator()
Initializes the object without a known last modified date or known properties.

LastModifiedCalculator(java.util.Map<java.lang.String,java.lang.String> properties, long lastModified)
After calling this constructor, the lastModified field will equal the supplied lastModified date and the properties field will contain a copy of the supplied properties.

Method Summary

long	getLastModified() Returns the lastModified date maintained by this object.
java.util.Map<java.lang.String,java.lang.String>	getProperties() Returns a copy of the last supplied properties which had changed.
void	update(java.util.Map<java.lang.String,java.lang.String> properties) Computes the lastModified field of this object based on the supplied map.

Methods inherited from class java.lang.Object

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

Constructor Detail

LastModifiedCalculator

public LastModifiedCalculator()

Initializes the object without a known last modified date or known properties. The update method must be called before these fields are accessed.

LastModifiedCalculator

public LastModifiedCalculator(java.util.Map<java.lang.String,java.lang.String> properties,
                              long lastModified)

After calling this constructor, the lastModified field will equal the supplied lastModified date and the properties field will contain a copy of the supplied properties.

Parameters:

properties - the initial properties for this object, not null

lastModified - the known last modification date for the supplied properties, not negative

Method Detail

update

public void update(java.util.Map<java.lang.String,java.lang.String> properties)

Computes the lastModified field of this object based on the supplied map. This method will persist a copy of the supplied properties if the properties differ from the last call to this method (or if this is the first call to the method).

Parameters:

properties - a new collection of properties

getProperties

public java.util.Map<java.lang.String,java.lang.String> getProperties()
                                                               throws java.lang.IllegalStateException

Returns a copy of the last supplied properties which had changed.

Returns:

the properties recorded by this object, never null

Throws:

java.lang.IllegalStateException - if the update method has not yet been called

getLastModified

public long getLastModified()
                     throws java.lang.IllegalStateException

Returns the lastModified date maintained by this object.

Returns:

the time at which the properties stored by this object were last modified

Throws:

java.lang.IllegalStateException - if the update method has not yet been called