com.antelmann.db
Class DefaultDBReference

java.lang.Object
  com.antelmann.db.DefaultDBReference

All Implemented Interfaces:

DBReference, Serializable

public class DefaultDBReference
extends Object
implements DBReference

this class implements a simple DBReference object. This implementation is immutable in regards to the database reference itself; merely the reference string can be altered after construction. A DefaultDBReference may be 'empty'.

Since:

22. August 2007, 22:16

Author:

Holger Antelmann

See Also:

Stub, Serialized Form

Field Summary

static DefaultDBReference

EMPTY_REF provides an empty DBReference (i.e. its id, class and string are null)

Fields inherited from interface com.antelmann.db.DBReference

REFERENCE_FLAVOR, REFERENCE_LIST_FLAVOR

Constructor Summary

DefaultDBReference(Database<?> db, Object referenceID, Class<? extends DBEntry> referenceClass)

DefaultDBReference(DBClassStore<?> store, Object referenceID)

DefaultDBReference(DBReference ref)

DefaultDBReference(Object referenceID, Class<?> referenceClass, String referenceString)

DefaultDBReference(String str)
an empty reference that merely contains the string as info

Method Summary

DBEntry	dereference(Database<?> db)
void	ensureReferenceString(Database<?> db)
static void	ensureReferenceString(DBReference ref, Database<?> db)
boolean	equals(Object obj) returns true if the given object is a DBReference and is also the same reference as defined in sameReference(DBReference)
static DefaultDBReference	fromEntry(DBEntry entry)
Class<? extends DBEntry>	getReferenceClass() indicates the type of DBEntry that represents the class of the reference ID, so that the instance could be looked up in a Database; this may be null only if the reference itself is null, too.
Object	getReferenceID() returns the ID of the DBEntry this instance refers to; this may be null only if the reference type returns null, too.
String	getReferenceString() provides a meaningful (displayable) description for the referenceID/referenceType or null if there is no reference for this entry.
static Comparator<DBReference>	getRefStringComparator()
int	hashCode()
static boolean	isAllNull(DBReference ref)
static boolean	isConsistent(DBReference ref) returns true only if the given reference applies to the rule that all relevant values (reference class and reference id) are both either null or non-null.
boolean	isEmpty()
static boolean	isEmpty(DBReference ref) if true is returned, this reference may still contain a reference string
boolean	isInstanceOf(Class<?> type)
static boolean	isInstanceof(DBReference ref, Class<?> type)
boolean	refersTo(DBEntry entry)
static boolean	refersTo(DBReference ref, DBEntry entry)
boolean	sameReference(DBReference ref)
static boolean	sameReference(DBReference ref1, DBReference ref2) determines whether both given references refer to the same entry
void	setReferenceString(String referenceString)
String	toString()
static DBReference	verify(DBReference ref, Class<?> type) verifies that the given reference is indeed of the given type
static DBReference	verifyBase(DBReference ref, Class<?> baseType)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY_REF

public static final DefaultDBReference EMPTY_REF

provides an empty DBReference (i.e. its id, class and string are null)

Constructor Detail

DefaultDBReference

public DefaultDBReference(DBClassStore<?> store,
                          Object referenceID)
                   throws DatabaseException

Throws:

DatabaseException

DefaultDBReference

public DefaultDBReference(Database<?> db,
                          Object referenceID,
                          Class<? extends DBEntry> referenceClass)

DefaultDBReference

public DefaultDBReference(Object referenceID,
                          Class<?> referenceClass,
                          String referenceString)
                   throws IllegalArgumentException

Parameters:

referenceID - the ID of the referenced entry (or null if this is an empty reference and the referenceClass is also null)

referenceClass - must be a class implementing DBEntry (in not null)

referenceString - an optional String representing the entry this reference is referring to

Throws:

IllegalArgumentException - if DBEntry class is not assignable from the non-null referenceClass

DefaultDBReference

public DefaultDBReference(DBReference ref)

DefaultDBReference

public DefaultDBReference(String str)

an empty reference that merely contains the string as info

Method Detail

fromEntry

public static DefaultDBReference fromEntry(DBEntry entry)

toString

public String toString()

Overrides:

toString in class Object

getReferenceID

public Object getReferenceID()

Description copied from interface: DBReference

returns the ID of the DBEntry this instance refers to; this may be null only if the reference type returns null, too.

Specified by:

getReferenceID in interface DBReference

See Also:

DBEntry.getID(), isConsistent(DBReference)

getReferenceClass

public Class<? extends DBEntry> getReferenceClass()

Description copied from interface: DBReference

indicates the type of DBEntry that represents the class of the reference ID, so that the instance could be looked up in a Database; this may be null only if the reference itself is null, too.

Specified by:

getReferenceClass in interface DBReference

See Also:

Database, DBEntry#getClass(), isConsistent(DBReference)

getReferenceString

public String getReferenceString()

Description copied from interface: DBReference

provides a meaningful (displayable) description for the referenceID/referenceType or null if there is no reference for this entry. Normally, this method would provide some cached info about the reference w/o having to dereference the link through the database. Note that this method may return null even if the reference itself is not null.

Specified by:

getReferenceString in interface DBReference

setReferenceString

public void setReferenceString(String referenceString)

ensureReferenceString

public void ensureReferenceString(Database<?> db)
                           throws DatabaseException

Throws:

DatabaseException

ensureReferenceString

public static void ensureReferenceString(DBReference ref,
                                         Database<?> db)
                                  throws DatabaseException,
                                         UnsupportedOperationException

Throws:

DatabaseException

UnsupportedOperationException

dereference

public DBEntry dereference(Database<?> db)
                    throws DatabaseException

Throws:

DatabaseException

isInstanceOf

public boolean isInstanceOf(Class<?> type)

isInstanceof

public static boolean isInstanceof(DBReference ref,
                                   Class<?> type)

refersTo

public boolean refersTo(DBEntry entry)

refersTo

public static boolean refersTo(DBReference ref,
                               DBEntry entry)

sameReference

public boolean sameReference(DBReference ref)

sameReference

public static boolean sameReference(DBReference ref1,
                                    DBReference ref2)

determines whether both given references refer to the same entry

isEmpty

public boolean isEmpty()

isEmpty

public static boolean isEmpty(DBReference ref)
                       throws InconsistentContentException

if true is returned, this reference may still contain a reference string

Throws:

InconsistentContentException - if only one (id or class) is null

isAllNull

public static boolean isAllNull(DBReference ref)

isConsistent

public static boolean isConsistent(DBReference ref)

returns true only if the given reference applies to the rule that all relevant values (reference class and reference id) are both either null or non-null.

verify

public static DBReference verify(DBReference ref,
                                 Class<?> type)
                          throws IllegalArgumentException

verifies that the given reference is indeed of the given type

Parameters:

ref - the reference to be checked

type - the expected type for the reference

Returns:

the given reference if it was successfully verified

Throws:

IllegalArgumentException - if the given reference was not of the given type

See Also:

Stub.verify(Stub, Class)

verifyBase

public static DBReference verifyBase(DBReference ref,
                                     Class<?> baseType)
                              throws IllegalArgumentException

Throws:

IllegalArgumentException

equals

public boolean equals(Object obj)

returns true if the given object is a DBReference and is also the same reference as defined in sameReference(DBReference)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getRefStringComparator

public static Comparator<DBReference> getRefStringComparator()