Class AbstractIdentifiedObject

All Implemented Interfaces:
Serializable, Formattable, Deprecable, Lenient­Comparable, Identified­Object
Direct Known Subclasses:
Abstract­Coordinate­Operation, Abstract­CS, Abstract­Datum, Abstract­Parameter­Descriptor, Abstract­Reference­System, Default­Coordinate­System­Axis, Default­Ellipsoid, Default­Operation­Method, Default­Prime­Meridian

public class AbstractIdentifiedObject extends FormattableObject implements IdentifiedObject, Formattable, LenientComparable, Deprecable, Serializable
Base class for objects identified by a name or a code. Those objects are typically geodetic datum (e.g. "World Geodetic System 1984"), Coordinate Reference System (e.g. "WGS 84 / World Mercator") or map projection (e.g. "Mercator (variant A)"). Those names, or a code (e.g. "EPSG:3395"), can be used for fetching an object from a database. However it is not sufficient to know the object name. We also need to know who define that name (the authority) since the same objects are often named differently depending on the providers, or conversely the same name is used for different objects depending on the provider.

The main information stored in an Identified­Object are:

  • a primary name, considered by the object creator as the preferred name,
  • an arbitrary amount of aliases, for example a list of names used by other providers,
  • an arbitrary amount of identifiers, typically primary keys in the provider database,
  • optional remarks.


This class is conceptually abstract, even if it is technically possible to instantiate it. Applications should instead instantiate the most specific subclass having a name starting by Default. However exceptions to this rule may occur when it is not possible to identify the exact type.
Example: It is sometime not possible to infer the exact coordinate system type from version 1 of Well Known Text format, for example when parsing a LOCAL_CS element. In such exceptional situation, a plain Abstract­CS object may be instantiated.
Identified­Object instances are created in two main ways:
  • Using an Object­Factory, in which case all properties can be explicitly specified.
  • Using an Authority­Factory, in which case only a code (typically a primary key) is specified. The authority and authority code values are set to the authority name of the factory object, and the authority code supplied by the client, respectively. All other information are fetched from the database.

Immutability and thread safety

This base class is immutable if the Citation, Reference­Identifier, Generic­Name and International­String instances given to the constructor are also immutable. Most SIS subclasses and related classes are immutable under similar conditions. This means that unless otherwise noted in the javadoc, Identified­Object instances created using only SIS factories and static constants can be shared by many objects and passed between threads without synchronization.
See Also:

Defined in the sis-referencing module

  • Field Details


      public static final String LOCALE_KEY
      Optional key which can be given to the constructor for specifying the locale to use for producing error messages. Notes:
      • The locale is not stored in any Abstract­Identified­Object property; its value is ignored if no error occurred at construction time.
      • The locale is used on a best effort basis; not all error messages may be localized.
      See Also:

      public static final String DEPRECATED_KEY
      Optional key which can be given to the constructor for specifying the object is deprecated. If deprecated, then the replacement should be specified in the remarks.
      Example: "superseded by code XYZ".
      See Also:
  • Constructor Details

  • Method Details

    • castOrCopy

      public static AbstractIdentifiedObject castOrCopy(IdentifiedObject object)
      Returns a SIS identified object implementation with the values of the given arbitrary implementation. This method performs the first applicable action in the following choices:
      object - the object to get as a SIS implementation, or null if none.
      a SIS implementation containing the values of the given object (may be the given object itself), or null if the argument was null.
    • getInterface

      public Class<? extends IdentifiedObject> getInterface()
      Returns the GeoAPI interface implemented by this class. This information is part of the data compared by equals(Object, Comparison­Mode).

      The default implementation returns Identified­Object​.class. Subclasses implementing a more specific GeoAPI interface shall override this method.


      The following invariants must hold for all Abstract­Identified­Object instances:
      • get­Interface().is­Instance(this) shall return true.
      • If A​.get­Class() == B​.get­Class() is true, then A​.get­Interface() == B​.get­Interface() shall be true. Note that the converse does not need to hold.
      the GeoAPI interface implemented by this class.
    • getName

      public ReferenceIdentifier getName()
      Returns the primary name by which this object is identified.
      Specified by:
      get­Name in interface Identified­Object
      the primary name.
      See Also:
    • getAlias

      public Collection<GenericName> getAlias()
      Returns alternative names by which this object is identified.
      Specified by:
      get­Alias in interface Identified­Object
      the aliases, or an empty collection if there is none.
      See Also:
    • getIdentifiers

      public Set<ReferenceIdentifier> getIdentifiers()
      Returns identifiers which references elsewhere the object's defining information. Alternatively identifiers by which this object can be referenced.
      Specified by:
      get­Identifiers in interface Identified­Object
      this object identifiers, or an empty set if there is none.
      See Also:
    • getDescription

      public InternationalString getDescription()
      Returns a narrative explanation of the role of this object.

      Default value

      The default implementation returns the description provided by this object's name.
      a narrative explanation of the role of this object, or null if none.
      See Also:
    • getRemarks

      public InternationalString getRemarks()
      Returns comments on or information about this object, including data source information. If this object is deprecated, then the remarks should give indication about the replacement (e.g. "superceded by …").
      Specified by:
      get­Remarks in interface Deprecable
      Specified by:
      get­Remarks in interface Identified­Object
      the remarks, or null if none.
    • isDeprecated

      public boolean isDeprecated()
      Returns true if this object is deprecated. Deprecated objects exist in some authority factories like the EPSG database. If this method returns true, then the remarks should give indication about the replacement (e.g. "superceded by …").
      Specified by:
      is­Deprecated in interface Deprecable
      true if this object is deprecated.
    • isHeuristicMatchForName

      public boolean isHeuristicMatchForName(String name)
      Returns true if either the primary name or at least one alias matches the given string according heuristic rules. The default implementation returns true if the given name is equal, ignoring aspects documented below, to one of the following names: The comparison ignores the following aspects:
      • Lower/upper cases.
      • Some Latin diacritical signs (e.g. "Réunion" and "Reunion" are considered equal).
      • All characters that are not letters or digits (e.g. "Mercator (1SP)" and "Mercator_1SP" are considered equal).
      • Namespaces or scopes, because this method is typically invoked with either the value of an other Identified­Object​.get­Name()​.get­Code() or with the Well Known Text (WKT) projection or parameter name.


      This method is invoked by SIS when comparing in IGNORE_METADATA mode two objects that can be differentiated only by some identifier (name or alias), like coordinate system axes, datum, parameters and operation methods. See equals(Object, Comparison­Mode) for more information.

      This method is also invoked when searching a parameter or operation method for a given name. For example the same projection is known as "Mercator (variant A)" (the primary name according EPSG) and "Mercator (1SP)" (the legacy name prior EPSG 7.6). Since the later is still in frequent use, SIS accepts it as an alias of the Mercator (variant A) projection.

      Overriding by subclasses

      Some subclasses add more flexibility to the comparisons:

      Future evolutions

      This method implements recommendations from the WKT 2 specification §B.5.2, together with heuristic rules learned from experience while trying to provide inter-operability with different data producers. Those rules may be adjusted in any future SIS version according experience gained while working with more data producers.
      name - the name to compare with the object name or aliases.
      true if the primary name or at least one alias matches the specified name.
      See Also:
    • equals

      public boolean equals(Object object, ComparisonMode mode)
      Compares this object with the given object for equality. The strictness level is controlled by the second argument, from stricter to more permissive values:
      Description of comparison modes
      STRICT: Verifies if the two objects are of the same class and compares all public properties, including SIS-specific (non standard) properties.
      BY_CONTRACT: Verifies if the two objects implement the same GeoAPI interface and compares all properties defined by that interface (name, identifiers, remarks, etc). The two objects do not need to be instances of the same implementation class and SIS-specific properties are ignored.
      IGNORE_METADATA: Compares only the properties relevant to coordinate transformations. Generally speaking, the content of the properties map given at construction time is considered ignorable metadata while the explicit arguments given to the constructor (if any) are considered non-ignorable. Note that there is some exceptions to this rule of thumb — see When object name matter below.
      APPROXIMATE: Same as IGNORE_METADATA, with some tolerance threshold on numerical values.
      ALLOW_VARIANT: Same as APPROXIMATE, but ignores coordinate system axes.
      DEBUG: Special mode for figuring out why two objects expected to be equal are not.
      The main guideline is that if source­CRS​.equals(target­CRS, IGNORE_METADATA) returns true, then the transformation from source­CRS to target­CRS should be the identity transform even if the two CRS do not have the same name.

      When object name matter

      Some subclasses (especially Default­Coordinate­System­Axis, Abstract­Datum and Default­Parameter­Descriptor) will compare the name even in IGNORE_METADATA mode, because objects of those types with different names have completely different meaning. For example nothing differentiate the "semi_major" and "semi_minor" parameters except the name. The name comparison may be lenient however, i.e. the rules may accept a name matching an alias. See is­Heuristic­Match­For­Name(String) for more information.

      Conformance to the equals(Object) method contract

      Comparison­Mode​.STRICT is the only mode compliant with the Object​.equals(Object) contract. For all other modes, the comparison is not guaranteed to be symmetric neither transitive. See Lenient­Comparable for more information.
      Specified by:
      equals in interface Lenient­Comparable
      object - the object to compare to this.
      mode - the strictness level of the comparison.
      true if both objects are equal according the given comparison mode.
      See Also:
    • equals

      public final boolean equals(Object object)
      Compares the specified object with this object for equality. This method is implemented as below (omitting assertions):
      return equals(other, ComparisonMode.STRICT);
      Subclasses shall override equals(Object, Comparison­Mode) instead of this method.
      Specified by:
      equals in interface Lenient­Comparable
      equals in class Object
      object - the other object (may be null).
      true if both objects are equal.
      See Also:
    • hashCode

      public final int hashCode()
      Returns a hash value for this identified object. Two Abstract­Identified­Object instances for which equals(Object) returns true shall have the same hash code value, if the hash codes are computed on the same JVM instance for both objects. The hash code value is not guaranteed to be stable between different versions of the Apache SIS library, or between libraries running on different JVM.

      Implementation note

      This method invokes compute­Hash­Code() when first needed, then caches the result. Subclasses shall override compute­Hash­Code() instead of this method.
      hash­Code in class Object
      the hash code value. This value may change in any future Apache SIS version.
    • computeHashCode

      protected long computeHashCode()
      Invoked by hash­Code() for computing the hash code when first needed. This method is invoked at most once in normal execution, or an arbitrary amount of times if Java assertions are enabled. The hash code value shall never change during the whole lifetime of this object in a JVM. The hash code value does not need to be the same in two different executions of the JVM.


      Subclasses can override this method for using more properties in hash code calculation. All compute­Hash­Code() methods shall invoke super​.compute­Hash­Code(), not hash­Code(). Example:
      protected long computeHashCode() {
          return super.computeHashCode() + 31 * Objects.hash(myProperties);
      the hash code value. This value may change in any future Apache SIS version.
    • formatTo

      protected String formatTo(Formatter formatter)
      Formats the inner part of the Well Known Text (WKT) representation for this object. The default implementation writes the following elements: Keywords and metadata (scope, extent, identifier and remarks) shall not be formatted here. For example if this formattable element is for a Geodetic­CRS[…] element, then subclasses shall write the content starting at the insertion point shown below:

      WKT example

      GeodeticCRS["WGS 84", ID["EPSG", 4326]]
                  (insertion point)

      Java code example

      // ... write the elements at the insertion point ...
      return "GeodeticCRS";

      Formatting non-standard WKT

      If the implementation can not represent this object without violating some WKT constraints, it can uses its own (non-standard) keywords but shall declare that it did so by invoking one of the Formatter​.set­Invalid­WKT(…) methods.

      Alternatively, the implementation may also have no WKT keyword for this object. In such case, this method shall return null.

      Specified by:
      format­To in class Formattable­Object
      formatter - the formatter where to format the inner content of this WKT element.
      the CamelCase keyword for the WKT element, or null if unknown.
      See Also:
    • formatTo

      public void formatTo(Formatter formatter, int flags, int width, int precision)
      Formats the name or identifier of this object using the provider formatter. This method is invoked when an Identified­Object object is formatted using the "%s" conversion specifier of Formatter. Users don't need to invoke this method explicitly.

      If the alternate flags is present (as in "%#s"), then this method will format the identifier (if present) instead of the object name.

      Specified by:
      format­To in interface Formattable
      formatter - the formatter in which to format this identified object.
      flags - whether to apply left alignment, use upper-case letters and/or use alternate form.
      width - minimal number of characters to write, padding with ' ' if necessary.
      precision - maximal number of characters to write, or -1 if no limit.
      See Also: