# Interface NamedDomainObjectCollection<T>

Type Parameters:
  `T` - The type of objects in this collection.

All Superinterfaces:
  `Collection<T>, DomainObjectCollection<T>, Iterable<T>`

All Known Subinterfaces:
  `ArtifactRepositoryContainer, ArtifactTransformReports, ArtifactTypeContainer, AuthenticationContainer, BuildDashboardReports, BuildTypeContainer, CheckstyleReports, CodeNarcReports, ConfigurationContainer, ConfigurationReports, DependencyReportContainer, DistributionContainer, ExtensiblePolymorphicDomainObjectContainer<T>, FlavorContainer, IvyConfigurationContainer, JacocoReportsContainer, MutableVersionCatalogContainer, NamedDomainObjectContainer<T>, NamedDomainObjectList<T>, NamedDomainObjectSet<T>, NativeToolChainRegistry, PlatformContainer, PmdReports, PolymorphicDomainObjectContainer<T>, PrebuiltLibraries, PublicationContainer, ReportContainer<T>, Repositories, RepositoryHandler, SoftwareComponentContainer, SourceSetContainer, TaskCollection<T>, TaskContainer, TestTaskReports`

public interface NamedDomainObjectCollection<T> extends DomainObjectCollection<T>

A `NamedDomainObjectCollection` represents a collection of objects that have an inherent, constant, name.

Objects to be added to a named domain object collection must implement `equals()` in such a way that no two objects with different names are considered equal. That is, all equality tests must consider the name as an equality key. Behavior is undefined if two objects with different names are considered equal by their `equals()` implementation.

All implementations must guarantee that all elements in the collection are uniquely named. That is, an attempt to add an object with a name equal to the name of any existing object in the collection will fail. Implementations may choose to simply return false from `add(T)` or to throw an exception.

Objects in the collection are accessible as read-only properties, using the name of the object as the property name. For example (assuming the 'name' property provides the object name):

    books.add(new Book(name: "gradle", title: null))
    books.gradle.title = "Gradle in Action"

A dynamic method is added for each object which takes a configuration closure. This is equivalent to calling `getByName(String, groovy.lang.Closure)`. For example:

    books.add(new Book(name: "gradle", title: null))
    books.gradle {
      title = "Gradle in Action"
    }

You can also use the `[]` operator to access the objects of a collection by name. For example:

    books.add(new Book(name: "gradle", title: null))
    books['gradle'].title = "Gradle in Action"

`Rule` objects can be attached to the collection in order to respond to requests for objects by name where no object with name exists in the collection. This mechanism can be used to create objects on demand. For example:

    books.addRule('create any') { books.add(new Book(name: "gradle", title: null)) }
    books.gradle.name == "gradle"

Since:
  0.9

- ## Method Summary

  Modifier and Type
  Method
  Description
  `boolean`
  `add(T e)`
  Adds an object to the collection, if there is no existing object in the collection with the same name.
  `boolean`
  `addAll(Collection<? extends T> c)`
  Adds any of the given objects to the collection that do not have the same name as any existing element.
  `Rule`
  `addRule(String description, Closure ruleAction)`
  Adds a rule to this collection.
  `Rule`
  `addRule(String description, Action<String> ruleAction)`
  Adds a rule to this collection.
  `Rule`
  `addRule(Rule rule)`
  Adds a rule to this collection.
  `@Nullable T`
  `findByName(String name)`
  Locates an object by name, returning null if there is no such object.
  `SortedMap<String,T>`
  `getAsMap()`
  Returns the objects in this collection, as a map from object name to object instance.
  `T`
  `getAt(String name)`
  Locates an object by name, failing if there is no such object.
  `T`
  `getByName(String name)`
  Locates an object by name, failing if there is no such object.
  `T`
  `getByName(String name, Closure configureClosure)`
  Locates an object by name, failing if there is no such object.
  `T`
  `getByName(String name, Action<? super T> configureAction)`
  Locates an object by name, failing if there is no such object.
  `NamedDomainObjectCollectionSchema`
  `getCollectionSchema()`
  Provides access to the schema of all created or registered named domain objects in this collection.
  `Namer<T>`
  `getNamer()`
  An object that represents the naming strategy used to name objects of this collection.
  `SortedSet<String>`
  `getNames()`
  Returns the names of the objects in this collection as a Set of Strings.
  `List<Rule>`
  `getRules()`
  Returns the rules used by this collection.
  `NamedDomainObjectCollection<T>`
  `matching(Closure spec)`
  Returns a collection which contains the objects in this collection which meet the given closure specification.
  `NamedDomainObjectCollection<T>`
  `matching(Spec<? super T> spec)`
  Returns a collection which contains the objects in this collection which meet the given specification.
  `NamedDomainObjectProvider<T>`
  `named(String name)`
  Locates a object by name, failing if there is no such object.
  `<S extends T>
  NamedDomainObjectProvider<S>`
  `named(String name, Class<S> type)`
  Locates a object by name and type, failing if there is no such object.
  `<S extends T>
  NamedDomainObjectProvider<S>`
  `named(String name, Class<S> type, Action<? super S> configurationAction)`
  Locates a object by name and type, failing if there is no such object.
  `NamedDomainObjectProvider<T>`
  `named(String name, Action<? super T> configurationAction)`
  Locates a object by name, failing if there is no such object.
  `default NamedDomainObjectCollection<T>`
  `named(Spec<String> nameFilter)`
  Returns a collection containing the objects with names matching the provided filter.
  `<S extends T>
  NamedDomainObjectCollection<S>`
  `withType(Class<S> type)`
  Returns a collection containing the objects in this collection of the given type.

  ### Methods inherited from interface Collection

  `clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray, toArray`

  ### Methods inherited from interface DomainObjectCollection

  `addAllLater, addLater, all, all, configureEach, disallowChanges, findAll, getElements, whenObjectAdded, whenObjectAdded, whenObjectRemoved, whenObjectRemoved, withType, withType`

  ### Methods inherited from interface Iterable

  `forEach`

- ## Method Details

  - ### add

    boolean add(T e)
    Adds an object to the collection, if there is no existing object in the collection with the same name.
    Specified by:
      `add` in interface `Collection<T>`
    Parameters:
      `e` - the item to add to the collection
    Returns:
      `true` if the item was added, or false if an item with the same name already exists.

  - ### addAll

    boolean addAll(Collection<? extends T> c)
    Adds any of the given objects to the collection that do not have the same name as any existing element.
    Specified by:
      `addAll` in interface `Collection<T>`
    Parameters:
      `c` - the items to add to the collection
    Returns:
      `true` if any item was added, or false if all items have non unique names within this collection.

  - ### getNamer

    Namer<T> getNamer()
    An object that represents the naming strategy used to name objects of this collection.
    Returns:
      Object representing the naming strategy.
    Since:
      1.0

  - ### getAsMap

    SortedMap<String,T> getAsMap()
    Returns the objects in this collection, as a map from object name to object instance.

    The map is ordered by the natural ordering of the object names (i.e. keys).

    This operation is eager and will cause all elements of the collection to be realized.

    Returns:
      The objects. Returns an empty map if this collection is empty.
    Since:
      0.9

  - ### getNames

    SortedSet<String> getNames()
    Returns the names of the objects in this collection as a Set of Strings.

    The set of names is in natural ordering.

    This operation is lazy and pending elements of this collection will not be realized.

    Returns:
      The names. Returns an empty set if this collection is empty.
    Since:
      1.8

  - ### findByName

    @Nullable T findByName(String name)
    Locates an object by name, returning null if there is no such object.

    This operation is eager and will cause the returned element, if any, to be realized.

    Parameters:
      `name` - The object name
    Returns:
      The object with the given name, or null if there is no such object in this collection.
    Since:
      0.9

  - ### getByName

    T getByName(String name) throws UnknownDomainObjectException
    Locates an object by name, failing if there is no such object.

    This operation is eager and will cause the returned element to be realized.

    Parameters:
      `name` - The object name
    Returns:
      The object with the given name. Never returns null.
    Throws:
      `UnknownDomainObjectException` - when there is no such object in this collection.
    Since:
      0.9

  - ### getByName

    T getByName(String name, Closure configureClosure) throws UnknownDomainObjectException
    Locates an object by name, failing if there is no such object. The given configure closure is executed against the object before it is returned from this method. The object is passed to the closure as its delegate.

    This operation is eager and will cause the returned element to be realized.

    Parameters:
      `name` - The object name
      `configureClosure` - The closure to use to configure the object.
    Returns:
      The object with the given name, after the configure closure has been applied to it. Never returns null.
    Throws:
      `UnknownDomainObjectException` - when there is no such object in this collection.
    Since:
      0.9

  - ### getByName

    T getByName(String name, Action<? super T> configureAction) throws UnknownDomainObjectException
    Locates an object by name, failing if there is no such object. The given configure action is executed against the object before it is returned from this method.

    This operation is eager and will cause the returned element to be realized.

    Parameters:
      `name` - The object name
      `configureAction` - The action to use to configure the object.
    Returns:
      The object with the given name, after the configure action has been applied to it. Never returns null.
    Throws:
      `UnknownDomainObjectException` - when there is no such object in this collection.
    Since:
      3.1

  - ### getAt

    T getAt(String name) throws UnknownDomainObjectException
    Locates an object by name, failing if there is no such object. This method is identical to `getByName(String)`. You can call this method in your build script by using the groovy `[]` operator.

    This operation is eager and will cause the returned element to be realized.

    Parameters:
      `name` - The object name
    Returns:
      The object with the given name. Never returns null.
    Throws:
      `UnknownDomainObjectException` - when there is no such object in this collection.
    Since:
      0.9

  - ### addRule

    Rule addRule(Rule rule)
    Adds a rule to this collection. The given rule is invoked when an unknown object is requested by name.
    Parameters:
      `rule` - The rule to add.
    Returns:
      The added rule.
    Since:
      1.0

  - ### addRule

    Rule addRule(String description, Closure ruleAction)
    Adds a rule to this collection. The given closure is executed when an unknown object is requested by name. The requested name is passed to the closure as a parameter.
    Parameters:
      `description` - The description of the rule.
      `ruleAction` - The closure to execute to apply the rule.
    Returns:
      The added rule.
    Since:
      1.0

  - ### addRule

    Rule addRule(String description, Action<String> ruleAction)
    Adds a rule to this collection. The given action is executed when an unknown object is requested by name. The requested name is passed to the action.
    Parameters:
      `description` - The description of the rule.
      `ruleAction` - The action to execute to apply the rule.
    Returns:
      The added rule.
    Since:
      3.3

  - ### getRules

    List<Rule> getRules()
    Returns the rules used by this collection.
    Returns:
      The rules, in the order they will be applied.
    Since:
      1.0

  - ### withType

    <S extends T> NamedDomainObjectCollection<S> withType(Class<S> type)
    Returns a collection containing the objects in this collection of the given type. The returned collection is live, so that when matching objects are later added to this collection, they are also visible in the filtered collection.

    This method is an intermediate operation. It does not change the realized/unrealized state of the elements in the collection.

    Specified by:
      `withType` in interface `DomainObjectCollection<T>`
    Parameters:
      `type` - The type of objects to find.
    Returns:
      The matching objects. Returns an empty collection if there are no such objects in this collection.

  - ### named

    @Incubating default NamedDomainObjectCollection<T> named(Spec<String> nameFilter)
    Returns a collection containing the objects with names matching the provided filter. The returned collection is live, so that when matching objects are added to this collection, they are also visible in the filtered collection.

    This method is an intermediate operation. It does not change the realized/unrealized state of the elements in the collection.

    Parameters:
      `nameFilter` - The specification to test names against.
    Returns:
      The collection of objects with names satisfying the filter. Returns an empty collection if there are no such objects in this collection.
    Since:
      8.6

  - ### matching

    NamedDomainObjectCollection<T> matching(Spec<? super T> spec)
    Returns a collection which contains the objects in this collection which meet the given specification. The returned collection is live, so that when matching objects are added to this collection, they are also visible in the filtered collection.

    This method is an intermediate eager operation. The application of the filter forces the realization of the collection elements.

    Specified by:
      `matching` in interface `DomainObjectCollection<T>`
    Parameters:
      `spec` - The specification to use.
    Returns:
      The collection of matching objects. Returns an empty collection if there are no such objects in this collection.

  - ### matching

    NamedDomainObjectCollection<T> matching(Closure spec)
    Returns a collection which contains the objects in this collection which meet the given closure specification. The returned collection is live, so that when matching objects are added to this collection, they are also visible in the filtered collection.

    This method is an intermediate eager operation. The application of the filter forces the realization of the collection elements.

    Specified by:
      `matching` in interface `DomainObjectCollection<T>`
    Parameters:
      `spec` - The specification to use. The closure gets a collection element as an argument.
    Returns:
      The collection of matching objects. Returns an empty collection if there are no such objects in this collection.

  - ### named

    NamedDomainObjectProvider<T> named(String name) throws UnknownDomainObjectException
    Locates a object by name, failing if there is no such object.

    This method is lazy and will not cause the returned element to be realized.

    Parameters:
      `name` - The object's name
    Returns:
      A `Provider` that will return the object when queried. The object may be created and configured at this point, if not already.
    Throws:
      `UnknownDomainObjectException` - If a object with the given name is not defined.
    Since:
      4.10

  - ### named

    NamedDomainObjectProvider<T> named(String name, Action<? super T> configurationAction) throws UnknownDomainObjectException
    Locates a object by name, failing if there is no such object. The given configure action is executed against the object before it is returned from the provider.

    This method is lazy and will not cause the returned element to be realized.

    Parameters:
      `name` - The object's name
    Returns:
      A `Provider` that will return the object when queried. The object may be created and configured at this point, if not already.
    Throws:
      `UnknownDomainObjectException` - If an object with the given name is not defined.
    Since:
      5.0

  - ### named

    <S extends T> NamedDomainObjectProvider<S> named(String name, Class<S> type) throws UnknownDomainObjectException
    Locates a object by name and type, failing if there is no such object.

    This method is lazy and will not cause the returned element to be realized.

    Parameters:
      `name` - The object's name
      `type` - The object's type
    Returns:
      A `Provider` that will return the object when queried. The object may be created and configured at this point, if not already.
    Throws:
      `UnknownDomainObjectException` - If an object with the given name is not defined.
    Since:
      5.0

  - ### named

    <S extends T> NamedDomainObjectProvider<S> named(String name, Class<S> type, Action<? super S> configurationAction) throws UnknownDomainObjectException
    Locates a object by name and type, failing if there is no such object. The given configure action is executed against the object before it is returned from the provider.

    This method is lazy and will not cause the returned element to be realized.

    Parameters:
      `name` - The object's name
      `type` - The object's type
      `configurationAction` - The action to use to configure the object.
    Returns:
      A `Provider` that will return the object when queried. The object may be created and configured at this point, if not already.
    Throws:
      `UnknownDomainObjectException` - If an object with the given name is not defined.
    Since:
      5.0

  - ### getCollectionSchema

    @Internal NamedDomainObjectCollectionSchema getCollectionSchema()
    Provides access to the schema of all created or registered named domain objects in this collection.
    Since:
      4.10