Package org.glassfish.hk2.utilities

Class DescriptorImpl

  • All Implemented Interfaces:
    java.io.Externalizable, java.io.Serializable, Descriptor
    Direct Known Subclasses:
    AbstractActiveDescriptor
    public class DescriptorImpl
extends java.lang.Object
implements Descriptor, java.io.Externalizable
    The implementation of the descriptor itself, with the bonus of being externalizable, and having writeable fields
    See Also:
    Serialized Form

    • Constructor Summary

      Constructors 
      Constructor Description
      DescriptorImpl()
      For serialization
      DescriptorImpl​(java.util.Set<java.lang.String> contracts, java.lang.String name, java.lang.String scope, java.lang.String implementation, java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadatas, java.util.Set<java.lang.String> qualifiers, DescriptorType descriptorType, DescriptorVisibility descriptorVisibility, HK2Loader loader, int rank, java.lang.Boolean proxiable, java.lang.Boolean proxyForSameScope, java.lang.String analysisName, java.lang.Long id, java.lang.Long locatorId)
      This creates this descriptor impl, taking all of the fields as given
      DescriptorImpl​(Descriptor copyMe)
      Does a deep copy of the incoming descriptor

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addAdvertisedContract​(java.lang.String addMe)
      Adds an advertised contract to the set of contracts advertised by this descriptor
      void addMetadata​(java.lang.String key, java.lang.String value)
      Adds a value to the list of values associated with this key
      void addMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadata)
      Adds all of the entries from this map to the existing descriptor's metadata.
      void addQualifier​(java.lang.String addMe)
      Adds the given string to the list of qualifiers
      void clearMetadata()
      Removes all metadata values
      static boolean descriptorEquals​(Descriptor a, Descriptor b)
      Tests if two descriptors are equal not taking into account the locator-id and server-id by comparing the following fields: implementation contracts name scope qualifiers descriptorType descriptorVisibility metadata proxiable proxyForSameScope analysisName
      private static <T> boolean equalMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> a, java.util.Map<java.lang.String,​java.util.List<java.lang.String>> b)  
      private static <T> boolean equalOrderedCollection​(java.util.Collection<T> a, java.util.Collection<T> b)  
      boolean equals​(java.lang.Object a)
      This equals matches only if the following fields of the descriptor match: implementation contracts name scope qualifiers descriptorType descriptorVisibility metadata proxiable proxyForSameScope analysisName
      java.util.Set<java.lang.String> getAdvertisedContracts()
      Returns the base class name of the contracts that this service describes.
      java.lang.String getClassAnalysisName()
      Returns the name of the ClassAnalyzer service that should be used to discover the constructors, initialization methods, field and postConstruct and preDestory methods.
      DescriptorType getDescriptorType()
      Returns CLASS if this is a class descriptor and FACTORY if this is a descriptor describing a factory for a type, in which case the implClass should point to the implementation class of the factory
      DescriptorVisibility getDescriptorVisibility()
      Returns the visibility of this descriptor.
      java.lang.String getImplementation()
      Returns the fully qualified class name of the implementation class.
      HK2Loader getLoader()
      This returns the loader that should be used when classloading this descriptor.
      java.lang.Long getLocatorId()
      This returns the id of the ServiceLocator which this descriptor is registered with.
      java.util.Map<java.lang.String,​java.util.List<java.lang.String>> getMetadata()
      Returns all of the metadata associated that this object should be registered with or looked up by
      java.lang.String getName()
      The name of this descriptor.
      java.util.Set<java.lang.String> getQualifiers()
      Returns all of the annotation classes that this object should be registered with or looked up by
      int getRanking()
      Returns the ranking of this descriptor.
      java.lang.String getScope()
      Returns the fully qualified class name of the scope annotation that should be associated with this descriptor.
      java.lang.Long getServiceId()
      This returns the unique identifier for this descriptor.
      int hashCode()  
      java.lang.Boolean isProxiable()
      If this returns true then the system will create a proxy for instances of this descriptor.
      java.lang.Boolean isProxyForSameScope()
      This value determines whether or not this service should be proxied when being injected into other services of the same scope.
      static void pretty​(java.lang.StringBuffer sb, Descriptor d)
      Will pretty print a descriptor
      void readExternal​(java.io.ObjectInput in)  
      boolean readObject​(java.io.BufferedReader in)
      This can be used to read in instances of this object that were previously written out with writeObject.
      private void reinitialize()  
      boolean removeAdvertisedContract​(java.lang.String removeMe)
      Removes an advertised contract from the set of contracts advertised by this descriptor
      boolean removeAllMetadata​(java.lang.String key)
      Removes all the metadata values associated with key
      boolean removeMetadata​(java.lang.String key, java.lang.String value)
      Removes the given value from the given key
      boolean removeQualifier​(java.lang.String removeMe)
      Removes the given qualifier from the list of qualifiers
      void setClassAnalysisName​(java.lang.String name)
      Sets the name of the service that will be used to analyze this class
      void setDescriptorType​(DescriptorType descriptorType)
      Sets the descriptor type
      void setDescriptorVisibility​(DescriptorVisibility descriptorVisibility)
      Sets the descriptor visilibity
      void setImplementation​(java.lang.String implementation)
      Sets the implementation
      void setLoader​(HK2Loader loader)
      Sets the loader to use with this descriptor
      void setLocatorId​(java.lang.Long locatorId)
      Sets the locator id for this descriptor
      void setMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadata)
      Sets the metadata of this DescriptorImpl to exactly the set of metadata in the incoming map.
      void setName​(java.lang.String name)
      Sets the name this descriptor should have
      void setProxiable​(java.lang.Boolean proxiable)
      Sets whether or not this descriptor should be proxied
      void setProxyForSameScope​(java.lang.Boolean proxyForSameScope)
      Sets whether or not to proxy this descriptor for other services in the same scope
      int setRanking​(int ranking)
      Returns the ranking of this descriptor.
      void setScope​(java.lang.String scope)
      Sets the scope this descriptor should have
      void setServiceId​(java.lang.Long id)
      Sets the service id for this descriptor
      java.lang.String toString()  
      void writeExternal​(java.io.ObjectOutput out)  
      void writeObject​(java.io.PrintWriter out)
      This writes this object to the data output stream in a human-readable format, excellent for writing out data files

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • serialVersionUID

        private static final long serialVersionUID
        For serialization
        See Also:
        Constant Field Values

      • PROXY_FOR_SAME_SCOPE_KEY

        private static final java.lang.String PROXY_FOR_SAME_SCOPE_KEY
        See Also:
        Constant Field Values

      • PROVIDE_METHOD_DT

        private static final java.lang.String PROVIDE_METHOD_DT
        See Also:
        Constant Field Values

      • SINGLETON_DIRECTIVE

        private static final java.lang.String SINGLETON_DIRECTIVE
        See Also:
        Constant Field Values

      • NOT_IN_CONTRACTS_DIRECTIVE

        private static final java.lang.String NOT_IN_CONTRACTS_DIRECTIVE
        See Also:
        Constant Field Values

      • SINGLETON_DIRECTIVE_CHAR

        private static final char SINGLETON_DIRECTIVE_CHAR
        See Also:
        Constant Field Values

      • NOT_IN_CONTRACTS_DIRECTIVE_CHAR

        private static final char NOT_IN_CONTRACTS_DIRECTIVE_CHAR
        See Also:
        Constant Field Values

      • EMPTY_CONTRACTS_SET

        private static final java.util.Set<java.lang.String> EMPTY_CONTRACTS_SET

      • EMPTY_QUALIFIER_SET

        private static final java.util.Set<java.lang.String> EMPTY_QUALIFIER_SET

      • EMPTY_METADATAS_MAP

        private static final java.util.Map<java.lang.String,​java.util.List<java.lang.String>> EMPTY_METADATAS_MAP

      • contracts

        private java.util.Set<java.lang.String> contracts

      • implementation

        private java.lang.String implementation

      • name

        private java.lang.String name

      • scope

        private java.lang.String scope

      • metadatas

        private java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadatas

      • qualifiers

        private java.util.Set<java.lang.String> qualifiers

      • rank

        private int rank

      • proxiable

        private java.lang.Boolean proxiable

      • proxyForSameScope

        private java.lang.Boolean proxyForSameScope

      • analysisName

        private java.lang.String analysisName

      • id

        private java.lang.Long id

      • locatorId

        private java.lang.Long locatorId

    • Constructor Detail

      • DescriptorImpl

        public DescriptorImpl()
        For serialization

      • DescriptorImpl

        public DescriptorImpl​(Descriptor copyMe)
        Does a deep copy of the incoming descriptor
        Parameters:
        copyMe - The descriptor to copy

      • DescriptorImpl

        public DescriptorImpl​(java.util.Set<java.lang.String> contracts,
                      java.lang.String name,
                      java.lang.String scope,
                      java.lang.String implementation,
                      java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadatas,
                      java.util.Set<java.lang.String> qualifiers,
                      DescriptorType descriptorType,
                      DescriptorVisibility descriptorVisibility,
                      HK2Loader loader,
                      int rank,
                      java.lang.Boolean proxiable,
                      java.lang.Boolean proxyForSameScope,
                      java.lang.String analysisName,
                      java.lang.Long id,
                      java.lang.Long locatorId)
        This creates this descriptor impl, taking all of the fields as given
        Parameters:
        contracts - The set of contracts this descriptor impl should advertise (should not be null)
        name - The name of this descriptor (may be null)
        scope - The scope of this descriptor. If null PerLookup is assumed
        implementation - The name of the implementation class (should not be null)
        metadatas - The metadata associated with this descriptor (should not be null)
        qualifiers - The set of qualifiers associated with this descriptor (should not be null)
        descriptorType - The type of this descriptor (should not be null)
        descriptorVisibility - The visibility this descriptor should have
        loader - The HK2Loader to associated with this descriptor (may be null)
        rank - The rank to initially associate with this descriptor
        proxiable - The proxiable value to associate with this descriptor (may be null)
        proxyForSameScope - The proxyForSameScope value to associate with this descriptor (may be null)
        analysisName - The name of the ClassAnalysis service to use
        id - The ID this descriptor should take (may be null)
        locatorId - The locator ID this descriptor should take (may be null)

    • Method Detail

      • getAdvertisedContracts

        public java.util.Set<java.lang.String> getAdvertisedContracts()
        Description copied from interface: Descriptor
        Returns the base class name of the contracts that this service describes. If the contract is a paramterized type this will return the raw class. If this service can be looked up by its implementation class then the name of the implementation class must also be found in this list
        Specified by:
        getAdvertisedContracts in interface Descriptor
        Returns:
        Will never return null, but may return an empty set. The returned strings are the fully qualified class names of contracts the predicate describes

      • addAdvertisedContract

        public void addAdvertisedContract​(java.lang.String addMe)
        Adds an advertised contract to the set of contracts advertised by this descriptor
        Parameters:
        addMe - The contract to add. May not be null

      • removeAdvertisedContract

        public boolean removeAdvertisedContract​(java.lang.String removeMe)
        Removes an advertised contract from the set of contracts advertised by this descriptor
        Parameters:
        removeMe - The contract to remove. May not be null
        Returns:
        true if removeMe was removed from the set

      • getImplementation

        public java.lang.String getImplementation()
        Description copied from interface: Descriptor
        Returns the fully qualified class name of the implementation class. If this is a factory descriptor then this will return the fully qualified name of the class implementing the factory interface.
        Specified by:
        getImplementation in interface Descriptor
        Returns:
        Might return null in some cases, but will usually return the fully qualified class name of the implementation class or of the factory class for this descriptor

      • setImplementation

        public void setImplementation​(java.lang.String implementation)
        Sets the implementation
        Parameters:
        implementation - The implementation this descriptor should have

      • getScope

        public java.lang.String getScope()
        Description copied from interface: Descriptor
        Returns the fully qualified class name of the scope annotation that should be associated with this descriptor.
        Specified by:
        getScope in interface Descriptor
        Returns:
        If this returns null then this descriptor is assumed to be in the default scope, which is PerLookup

      • setScope

        public void setScope​(java.lang.String scope)
        Sets the scope this descriptor should have
        Parameters:
        scope - The scope of this descriptor

      • getName

        public java.lang.String getName()
        Description copied from interface: Descriptor
        The name of this descriptor. Note that if this returns not null then there must also be the Named qualifier in the set of qualifiers with the same value

        Specified by:
        getName in interface Descriptor
        Returns:
        The name of this descriptor, or null if there is no name associated with this qualifier

      • setName

        public void setName​(java.lang.String name)
        Sets the name this descriptor should have
        Parameters:
        name - The name for this descriptor

      • getQualifiers

        public java.util.Set<java.lang.String> getQualifiers()
        Description copied from interface: Descriptor
        Returns all of the annotation classes that this object should be registered with or looked up by
        Specified by:
        getQualifiers in interface Descriptor
        Returns:
        Never returns null, but may return an empty set. The set of fully qualified class names that are annotations that this object must have

      • addQualifier

        public void addQualifier​(java.lang.String addMe)
        Adds the given string to the list of qualifiers
        Parameters:
        addMe - The fully qualified class name of the qualifier to add. May not be null

      • removeQualifier

        public boolean removeQualifier​(java.lang.String removeMe)
        Removes the given qualifier from the list of qualifiers
        Parameters:
        removeMe - The fully qualifier class name of the qualifier to remove. May not be null
        Returns:
        true if the given qualifier was removed

      • getDescriptorType

        public DescriptorType getDescriptorType()
        Description copied from interface: Descriptor
        Returns CLASS if this is a class descriptor and FACTORY if this is a descriptor describing a factory for a type, in which case the implClass should point to the implementation class of the factory
        Specified by:
        getDescriptorType in interface Descriptor
        Returns:
        Either CLASS or PROVIDE_METHOD

      • setDescriptorType

        public void setDescriptorType​(DescriptorType descriptorType)
        Sets the descriptor type
        Parameters:
        descriptorType - The descriptor type. May not be null

      • getDescriptorVisibility

        public DescriptorVisibility getDescriptorVisibility()
        Description copied from interface: Descriptor
        Returns the visibility of this descriptor.

        If the visibility is NORMAL then this descriptor may be seen by all children locators of the locator in which this descriptor is bound

        If the visibility is LOCAL then this descriptor may only be seen by the servcie locator in which it is bound, and in none of the children of that locator

        Specified by:
        getDescriptorVisibility in interface Descriptor
        Returns:
        Either NORMAL or LOCAL

      • setDescriptorVisibility

        public void setDescriptorVisibility​(DescriptorVisibility descriptorVisibility)
        Sets the descriptor visilibity
        Parameters:
        descriptorVisibility - The visibility this descriptor should have

      • getMetadata

        public java.util.Map<java.lang.String,​java.util.List<java.lang.String>> getMetadata()
        Description copied from interface: Descriptor
        Returns all of the metadata associated that this object should be registered with or looked up by
        Specified by:
        getMetadata in interface Descriptor
        Returns:
        Never returns null, but may return an empty set. The set of metadata associated with the object. The values in the returned map will never be null, and will always have at least one member

      • setMetadata

        public void setMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadata)
        Sets the metadata of this DescriptorImpl to exactly the set of metadata in the incoming map. Any previous metadata values will be removed. A deep copy of the incoming map will be made, so it is safe to use the input map after use of this API
        Parameters:
        metadata - The non-null metadata that this descriptor should have

      • addMetadata

        public void addMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> metadata)
        Adds all of the entries from this map to the existing descriptor's metadata. None of the keys in the map may have the '=' character
        Parameters:
        metadata - The non-null but possibly empty list of fields to add to the metadata map

      • addMetadata

        public void addMetadata​(java.lang.String key,
                        java.lang.String value)
        Adds a value to the list of values associated with this key
        Parameters:
        key - The key to which to add the value. May not be null. May not contain the character '='
        value - The value to add. May not be null

      • removeMetadata

        public boolean removeMetadata​(java.lang.String key,
                              java.lang.String value)
        Removes the given value from the given key
        Parameters:
        key - The key of the value to remove. May not be null, and may not contain the character '='
        value - The value to remove. May not be null
        Returns:
        true if the value was removed

      • removeAllMetadata

        public boolean removeAllMetadata​(java.lang.String key)
        Removes all the metadata values associated with key
        Parameters:
        key - The key of the metadata values to remove
        Returns:
        true if any value was removed

      • clearMetadata

        public void clearMetadata()
        Removes all metadata values

      • getLoader

        public HK2Loader getLoader()
        Description copied from interface: Descriptor
        This returns the loader that should be used when classloading this descriptor. If this method returns null then the class will be loaded with the classloader of the Injectee if there is one, or with the classloader that loaded HK2 itself; failing that the context class loader on the thread will be tried.
        Specified by:
        getLoader in interface Descriptor
        Returns:
        An HK2Loader that can be used to load this descriptor, or null if the default classloading algorithm should be used

      • setLoader

        public void setLoader​(HK2Loader loader)
        Sets the loader to use with this descriptor
        Parameters:
        loader - The loader to use with this descriptor

      • getRanking

        public int getRanking()
        Description copied from interface: Descriptor
        Returns the ranking of this descriptor. Rankings with higher value will be considered "better" than rankings of lower value. Descriptors with the same ranking will be returned in the reverse ServiceID order (in other words, the least service ID is considered "better" than any higher service ID).
        Specified by:
        getRanking in interface Descriptor
        Returns:
        the ranking that should be associated with this descriptor

      • setRanking

        public int setRanking​(int ranking)
        Description copied from interface: Descriptor
        Returns the ranking of this descriptor. Rankings with higher value will be considered "better" than rankings of lower value. Descriptors with the same ranking will be returned in the reverse ServiceID order (in other words, the least service ID is considered "better" than any higher service ID).

        The ranking of a service may change at any time during the life of the descriptor

        Specified by:
        setRanking in interface Descriptor
        Parameters:
        ranking - The new ranking this descriptor should have
        Returns:
        the previous ranking that this descriptor had

      • getServiceId

        public java.lang.Long getServiceId()
        Description copied from interface: Descriptor
        This returns the unique identifier for this descriptor. This field will be ignored upon binding, and will then be assigned by the system. However, this field can be set on search operations, in which case this search will match exactly one Provider in the system.
        Specified by:
        getServiceId in interface Descriptor
        Returns:
        The service id for this object. Note that this field may return null if this is an initial bind, as it is not the responsibility of the binder to set this value. If this returns non-null on a bind operation the return value will be ignored

      • setServiceId

        public void setServiceId​(java.lang.Long id)
        Sets the service id for this descriptor
        Parameters:
        id - the service id for this descriptor

      • isProxiable

        public java.lang.Boolean isProxiable()
        Description copied from interface: Descriptor
        If this returns true then the system will create a proxy for instances of this descriptor. As with all proxies, the proxy created will also implement the ProxyCtl interface

        It is an error for this method to return true if the scope that this descriptor is in is Unproxiable (such as PerLookup).

        Specified by:
        isProxiable in interface Descriptor
        Returns:
        true if this descriptor must be proxied, false if this descriptor must NOT be proxied (even if it is in an Unproxiable scope) and null if this descriptor should take its proxiable status from the scope it is in (i.e., it will only be proxied if the scope is marked Proxiable)

      • setProxiable

        public void setProxiable​(java.lang.Boolean proxiable)
        Sets whether or not this descriptor should be proxied
        Parameters:
        proxiable - if true then this descriptor will be proxied. If false then this descriptor will not be proxied. If null this descriptor will follow the rules of the scope it is in

      • isProxyForSameScope

        public java.lang.Boolean isProxyForSameScope()
        Description copied from interface: Descriptor
        This value determines whether or not this service should be proxied when being injected into other services of the same scope. If a scope is proxiable then it will have a default setting for whether or not its services should be proxied when being injected into the same scope. If this method returns null then the default setting for the scope will be used. Otherwise the value returned will determine whether or not this service will be proxied when being injected into a service of the same scope.
        Specified by:
        isProxyForSameScope in interface Descriptor
        Returns:
        null if this descriptor should use the default ProxyForSameScope value for the scope. If it returns true then this service will be proxied even when being injected into the same scope. If it returns false then this service will NOT be proxied when being injected into the same scope (i.e., it cannot be used for lazy initialization of the service when injected into the same scope)

      • setProxyForSameScope

        public void setProxyForSameScope​(java.lang.Boolean proxyForSameScope)
        Sets whether or not to proxy this descriptor for other services in the same scope
        Parameters:
        proxyForSameScope - if true then this descriptor will be proxied for services in the same scope. If false then this descriptor will not be proxied for services in the same scope. If null this descriptor will follow the rules of the scope it is in

      • getClassAnalysisName

        public java.lang.String getClassAnalysisName()
        Description copied from interface: Descriptor
        Returns the name of the ClassAnalyzer service that should be used to discover the constructors, initialization methods, field and postConstruct and preDestory methods. If null the default implementation will be used. Will be ignored for descriptors that are not automatically analyzed by hk2
        Specified by:
        getClassAnalysisName in interface Descriptor
        Returns:
        the possibly null name of the ClassAnalysis service that should be used to analyze the class represented by this descriptor. If null then the HK2 default analysis will be performed

      • setClassAnalysisName

        public void setClassAnalysisName​(java.lang.String name)
        Sets the name of the service that will be used to analyze this class
        Parameters:
        name - The name of the ClassAnalyzer service that should be used to analyze this descriptor

      • getLocatorId

        public java.lang.Long getLocatorId()
        Description copied from interface: Descriptor
        This returns the id of the ServiceLocator which this descriptor is registered with. Returns null if this descriptor is not yet registered with a ServiceLocator
        Specified by:
        getLocatorId in interface Descriptor
        Returns:
        The id of the ServiceLocator this Descriptor is registered with, or null if this Descriptor is not registered with a ServiceLocator

      • setLocatorId

        public void setLocatorId​(java.lang.Long locatorId)
        Sets the locator id for this descriptor
        Parameters:
        locatorId - the locator id for this descriptor

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • equalOrderedCollection

        private static <T> boolean equalOrderedCollection​(java.util.Collection<T> a,
                                                  java.util.Collection<T> b)

      • equalMetadata

        private static <T> boolean equalMetadata​(java.util.Map<java.lang.String,​java.util.List<java.lang.String>> a,
                                         java.util.Map<java.lang.String,​java.util.List<java.lang.String>> b)

      • descriptorEquals

        public static boolean descriptorEquals​(Descriptor a,
                                       Descriptor b)
        Tests if two descriptors are equal not taking into account the locator-id and server-id by comparing the following fields:
        • implementation
        • contracts
        • name
        • scope
        • qualifiers
        • descriptorType
        • descriptorVisibility
        • metadata
        • proxiable
        • proxyForSameScope
        • analysisName
        Parameters:
        a - The possibly null descriptor to compare
        b - The possibly null descriptor to compare
        Returns:
        true if they are the same, false otherwise

      • equals

        public boolean equals​(java.lang.Object a)
        This equals matches only if the following fields of the descriptor match:
        • implementation
        • contracts
        • name
        • scope
        • qualifiers
        • descriptorType
        • descriptorVisibility
        • metadata
        • proxiable
        • proxyForSameScope
        • analysisName
        Overrides:
        equals in class java.lang.Object
        Parameters:
        a - The object to compare to this one. May be null (which will result in a false)
        Returns:
        true if the descriptors are equal

      • pretty

        public static void pretty​(java.lang.StringBuffer sb,
                          Descriptor d)
        Will pretty print a descriptor
        Parameters:
        sb - The string buffer put the pretty print into
        d - The descriptor to write

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • writeObject

        public void writeObject​(java.io.PrintWriter out)
                 throws java.io.IOException
        This writes this object to the data output stream in a human-readable format, excellent for writing out data files
        Parameters:
        out - The output stream to write this object out to
        Throws:
        java.io.IOException - on failure

      • reinitialize

        private void reinitialize()

      • readObject

        public boolean readObject​(java.io.BufferedReader in)
                   throws java.io.IOException
        This can be used to read in instances of this object that were previously written out with writeObject. Useful for reading from external data files
        Parameters:
        in - The reader to read from
        Returns:
        true if a descriptor was read, false otherwise. This is useful if reading a file that might have comments at the end
        Throws:
        java.io.IOException - on failure

      • writeExternal

        public void writeExternal​(java.io.ObjectOutput out)
                   throws java.io.IOException
        Specified by:
        writeExternal in interface java.io.Externalizable
        Throws:
        java.io.IOException

      • readExternal

        public void readExternal​(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException
        Specified by:
        readExternal in interface java.io.Externalizable
        Throws:
        java.io.IOException
        java.lang.ClassNotFoundException