Package org.apache.jena.util

Class OneToManyMap<From,​To>

  • All Implemented Interfaces:
    java.util.Map<From,​To>
    public class OneToManyMap<From,​To>
extends java.lang.Object
implements java.util.Map<From,​To>
    An extension to a standard map that supports one-to-many mappings: that is, there may be zero, one or many values corresponding to a given key.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  OneToManyMap.Entry<From,​To>
      Helper class to implement the Map.Entry interface to enumerate entries in the map

    • Constructor Summary

      Constructors 
      Constructor Description
      OneToManyMap()
      Construct a new empty one-to-many map
      OneToManyMap​(OneToManyMap<From,​To> map)
      Construct a new one-to-many map whose contents are initialised from the existing map.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clear all entries from the map.
      boolean contains​(java.lang.Object key, java.lang.Object value)
      Answer true if this mapping contains the pair (key, value).
      boolean containsKey​(java.lang.Object key)
      Answer true if the map contains the given value as a key.
      boolean containsValue​(java.lang.Object value)
      Answer true if the map contains the given object as a value stored against any key.
      java.util.Set<java.util.Map.Entry<From,​To>> entrySet()
      Answer a set of the mappings in this map.
      boolean equals​(java.lang.Object o)
      Compares the specified object with this map for equality.
      To get​(java.lang.Object key)
      Get a value for this key.
      java.util.Iterator<To> getAll​(java.lang.Object key)
      Answer an iterator over all of the values for the given key.
      int hashCode()
      Returns the hash code value for this map.
      boolean isEmpty()
      Answer true if the map is empty of key-value mappings.
      java.util.Set<From> keySet()
      Answer a set of the keys in this map
      To put​(From key, To value)
      Associates the given value with the given key.
      void putAll​(java.util.Map<? extends From,​? extends To> m)
      Put all entries from one map into this map.
      To remove​(java.lang.Object key)
      Remove all of the associations for the given key.
      boolean remove​(java.lang.Object key, java.lang.Object value)
      Remove the specific association between the given key and value.
      int size()
      Answer the number of key-value mappings in the map
      java.lang.String toString()
      Answer a string representation of this map.
      java.util.Collection<To> values()
      Returns a collection view of the values contained in this map.

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

      • Methods inherited from interface java.util.Map

        compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, replace, replace, replaceAll

    • Constructor Detail

      • OneToManyMap

        public OneToManyMap()

        Construct a new empty one-to-many map

      • OneToManyMap

        public OneToManyMap​(OneToManyMap<From,​To> map)

        Construct a new one-to-many map whose contents are initialised from the existing map.

        Parameters:
        map - An existing one-to-many map

    • Method Detail

      • clear

        public void clear()
        Clear all entries from the map.
        Specified by:
        clear in interface java.util.Map<From,​To>

      • containsKey

        public boolean containsKey​(java.lang.Object key)
        Answer true if the map contains the given value as a key.
        Specified by:
        containsKey in interface java.util.Map<From,​To>
        Parameters:
        key - The key object to test for
        Returns:
        True or false

      • containsValue

        public boolean containsValue​(java.lang.Object value)
        Answer true if the map contains the given object as a value stored against any key. Note that this is quite an expensive operation in the current implementation.
        Specified by:
        containsValue in interface java.util.Map<From,​To>
        Parameters:
        value - The value to test for
        Returns:
        True if the value is in the map

      • contains

        public boolean contains​(java.lang.Object key,
                        java.lang.Object value)

        Answer true if this mapping contains the pair (key, value).

        Parameters:
        key - A key object
        value - A value object
        Returns:
        True if key has value as one of its values in this mapping

      • entrySet

        public java.util.Set<java.util.Map.Entry<From,​To>> entrySet()
        Answer a set of the mappings in this map. Each member of the set will be a Map.Entry value.
        Specified by:
        entrySet in interface java.util.Map<From,​To>
        Returns:
        A Set of the mappings as Map.Entry values.

      • equals

        public boolean equals​(java.lang.Object o)
        Compares the specified object with this map for equality. Returns true if the given object is also a map and the two Maps represent the same mappings. More formally, two maps t1 and t2 represent the same mappings if t1.entrySet().equals(t2.entrySet()). This ensures that the equals method works properly across different implementations of the Map interface.
        Specified by:
        equals in interface java.util.Map<From,​To>
        Overrides:
        equals in class java.lang.Object
        Parameters:
        o - The object to be compared for equality with this map.
        Returns:
        True if the specified object is equal to this map.

      • get

        public To get​(java.lang.Object key)
        Get a value for this key. Since this map is explicitly designed to allow there to be more than one mapping per key, this method will return an undetermined instance of the mapping. If no mapping exists, or the selected value is null, null is returned.
        Specified by:
        get in interface java.util.Map<From,​To>
        Parameters:
        key - The key to access the map.
        Returns:
        One of the values this key corresponds to, or null.
        See Also:
        getAll(java.lang.Object)

      • getAll

        public java.util.Iterator<To> getAll​(java.lang.Object key)
        Answer an iterator over all of the values for the given key. An iterator is always supplied, even if the key is not present.
        Parameters:
        key - The key object
        Returns:
        An iterator over all of the values for this key in the map

      • hashCode

        public int hashCode()
        Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hashCodes of each entry in the map's entrySet view. This ensures that t1.equals(t2) implies that t1.hashCode()==t2.hashCode() for any two maps t1 and t2, as required by the general contract of Object.hashCode
        Specified by:
        hashCode in interface java.util.Map<From,​To>
        Overrides:
        hashCode in class java.lang.Object

      • isEmpty

        public boolean isEmpty()
        Answer true if the map is empty of key-value mappings.
        Specified by:
        isEmpty in interface java.util.Map<From,​To>
        Returns:
        True if there are no entries.

      • keySet

        public java.util.Set<From> keySet()
        Answer a set of the keys in this map
        Specified by:
        keySet in interface java.util.Map<From,​To>
        Returns:
        The keys of the map as a Set

      • put

        public To put​(From key,
              To value)
        Associates the given value with the given key. Since this map formulation allows many values for one key, previous associations with the key are not lost. Consequently, the method always returns null (since the replaced value is not defined).
        Specified by:
        put in interface java.util.Map<From,​To>
        Parameters:
        key - The key object
        value - The value object
        Returns:
        Null.

      • putAll

        public void putAll​(java.util.Map<? extends From,​? extends To> m)

        Put all entries from one map into this map. Tests for m being a OneToManyMap, and, if so, copies all of the entries for each key.

        Specified by:
        putAll in interface java.util.Map<From,​To>
        Parameters:
        m - The map whose contents are to be copied into this map

      • remove

        public To remove​(java.lang.Object key)
        Remove all of the associations for the given key. If only a specific association is to be removed, use remove( java.lang.Object, java.lang.Object ) instead. Has no effect if the key is not present in the map. Since no single specific association with the key is defined, this method always returns null.
        Specified by:
        remove in interface java.util.Map<From,​To>
        Parameters:
        key - All associations with this key will be removed
        Returns:
        null

      • remove

        public boolean remove​(java.lang.Object key,
                      java.lang.Object value)

        Remove the specific association between the given key and value. Has no effect if the association is not present in the map. If all values for a particular key have been removed post removing this particular association, the key will no longer appear as a key in the map.

        Specified by:
        remove in interface java.util.Map<From,​To>
        Parameters:
        key - The key object
        value - The value object
        Returns:
        true if an entry was removed.

      • size

        public int size()

        Answer the number of key-value mappings in the map

        Specified by:
        size in interface java.util.Map<From,​To>
        Returns:
        The number of key-value pairs.

      • values

        public java.util.Collection<To> values()

        Returns a collection view of the values contained in this map. Specifically, this will be a set, so duplicate values that appear for multiple keys are suppressed.

        Specified by:
        values in interface java.util.Map<From,​To>
        Returns:
        A set of the values contained in this map.

      • toString

        public java.lang.String toString()

        Answer a string representation of this map. This can be quite a long string for large maps.

        Overrides:
        toString in class java.lang.Object