Package net.sf.basedb.core.data

Class BasicData

java.lang.Object
net.sf.basedb.core.data.BasicData
All Implemented Interfaces:
IdentifiableData
Direct Known Subclasses:
AnnotationData, AnnotationSetData, AnyToAnyData, ArrayDesignBlockData, ArrayDesignPlateData, BioAssayData, BioAssaySetData, BioMaterialEventData, BioMaterialEventSourceData, BioPlateEventParticipantData, BioPlateEventTypeData, BioPlateTypeData, BioWellData, ChangeHistoryData, ChangeHistoryDetailData, ContextData, DataCubeColumnData, DataCubeData, DataCubeExtraValueData, DataCubeFilterData, DataCubeLayerData, DataFileTypeData, DiskUsageData, ExtraValueData, ExtraValueTypeData, FeatureData, FileSetData, FileSetMemberData, GroupData, HelpData, ItemListSyncFilterData, ItemSubtypeData, ItemSubtypeFileTypeData, JobAgentSettingsData, KeyData, MessageData, MimeTypeData, NewsData, OwnedData, ParameterValueData, PasswordData, PlateEventData, PlateEventTypeData, PlateGeometryData, PlatformData, PlatformFileTypeData, PlatformVariantData, PluginTypeData, QuantityData, QuotaData, QuotaTypeData, RawData, ReporterData, ReporterTypeData, RoleData, RootRawBioAssayData, SchemaVersionData, SessionData, SettingData, TransformationData, UnitData, UnitSymbolData, UserData, UserDeviceData, VirtualDbData, WellData
public abstract class BasicData
extends Object
implements IdentifiableData
This is the root superclass of all data classes. Each class must inherit from this class or one of the subclasses. The main purpose of this class is to handle object identity. It contains a Hibernate mapping for the getId() property and overrides the default implementations of the equals(Object) and hashCode() methods.

For all practical purposes object identity is the same as database identity, ie. two objects are considered equal if they reference the same row in the database. Objects that has not yet been saved to the database should be handled carefully and not be put into Set:s or Map:s since that may break the contract for the equals() and hashCode() methods.

We recommend that the equals() and hashCode() methods not are overridden in subclasses, unless you really know what you are doing. Actually, we would have liked to make the methods final but that would disable the proxy feature of Hibernate.

Version:
2.0
Author:
Nicklas
See Also:
Developer documentation: Basic classes and interfaces

  • Field Summary

    Fields
    Modifier and Type Field Description
    private int hashCode
    Stores the hash code of the item.
    private int id  
    private int version  

  • Constructor Summary

    Constructors
    Constructor Description
    BasicData()  

  • Method Summary

    Modifier and Type Method Description
    boolean equals​(Object other)
    Check if this item is equal to another item.
    int getId()
    Get the id of the item.
    int getVersion()
    Get the version of the item.
    int hashCode()
    For new items (getId() returns 0) the hash code is the same as returned by the System.identityHashCode() method.
    (package private) void setId​(int id)
    Set the id of the item.
    (package private) void setVersion​(int version)
    Set the version of the item.
    String toString()
    The string will look like ClassName[id=55] or ClassName[new].

    Methods inherited from class java.lang.Object

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

  • Field Details

    • hashCode

      private int hashCode
      Stores the hash code of the item. This value is initialised the first time it is asked for by an application.
      See Also:
      hashCode()

    • id

      private int id

    • version

      private int version

  • Constructor Details

    • BasicData

      public BasicData()

  • Method Details

    • toString

      public String toString()
      The string will look like ClassName[id=55] or ClassName[new].
      Overrides:
      toString in class Object

    • equals

      public boolean equals​(Object other)
      Check if this item is equal to another item. They are considered to be equal if they are of the same class and have the same ID. Items that has not yet been assigned an ID (id == 0) are equal only if they refer to the same object instance. We must also handle the fact that the other object can be a Hibernate proxy, which is a dynamically generated subclass of the actual class. Do not override this method in a subclass!
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      For new items (getId() returns 0) the hash code is the same as returned by the System.identityHashCode() method. Items loaded from the database uses the id as the hash code. We must also consider the case were a new object is saved to the database. Our recommendation is to not place the object in Set (or other structure) that calls the hashCode method before the object is saved to the database. If you do that the contract for the equals()/hashCode() method is broken and equals() may return true even if hashCode() returns different values. Do not override this method in a subclass!
      Overrides:
      hashCode in class Object

    • getId

      public int getId()
      Get the id of the item. The id is automatically generated by the database the first time the item is saved to the database. A new item has the value 0.
      Specified by:
      getId in interface IdentifiableData
      Returns:
      The id of the item or 0
      Hibernate: id
      column="`id`" type="int" generator-class="native" unsaved-value="0"

    • setId

      void setId​(int id)
      Set the id of the item. Only used by Hibernate.
      Parameters:
      id - The id of the item

    • getVersion

      @NotLoggable public int getVersion()
      Get the version of the item. This value is used by Hibernate to check if another process or thread has modified the corresponding row in the databse since this item was loaded from the. If that is the case, this item can't be saved and an exception will be thrown.
      Specified by:
      getVersion in interface IdentifiableData
      Hibernate: version
      column="`version`" type="int"

    • setVersion

      void setVersion​(int version)
      Set the version of the item. Only used by Hibernate.
      Parameters:
      version - The version of the item