OneToManyMap (Apache Jena)

java.lang.Object
- org.apache.jena.util.OneToManyMap<From,To>

All Implemented Interfaces:

Map<From,To>
```
public class OneToManyMap<From,To>
extends Object
implements 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 and Description

static class OneToManyMap.Entry<From,To>
Helper class to implement the Map.Entry interface to enumerate entries in the map

Nested Classes
Modifier and Type	Class and 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 and 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 and Description
`void`	`clear()` Clear all entries from the map.
`boolean`	`contains(Object key, Object value)` Answer true if this mapping contains the pair `(key, value)`.
`boolean`	`containsKey(Object key)` Answer true if the map contains the given value as a key.
`boolean`	`containsValue(Object value)` Answer true if the map contains the given object as a value stored against any key.
`Set<Map.Entry<From,To>>`	`entrySet()` Answer a set of the mappings in this map.
`boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`To`	`get(Object key)` Get a value for this key.
`Iterator<To>`	`getAll(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.
`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(Map<? extends From,? extends To> m)` Put all entries from one map into this map.
`To`	`remove(Object key)` Remove all of the associations for the given key.
`boolean`	`remove(Object key, Object value)` Remove the specific association between the given key and value.
`int`	`size()` Answer the number of key-value mappings in the map
`String`	`toString()` Answer a string representation of this map.
`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 Map<From,To>
  - containsKey
```
public boolean containsKey(Object key)
```
    Answer true if the map contains the given value as a key.
    
    Specified by:
    
    containsKey in interface Map<From,To>
    
    Parameters:
    
    key - The key object to test for
    
    Returns:
    
    True or false
  - containsValue
```
public boolean containsValue(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 Map<From,To>
    
    Parameters:
    
    value - The value to test for
    
    Returns:
    
    True if the value is in the map
  - contains
```
public boolean contains(Object key,
                        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 Set<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 Map<From,To>
    
    Returns:
    
    A Set of the mappings as Map.Entry values.
  - equals
```
public boolean equals(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 Map<From,To>
    
    Overrides:
    
    equals in class 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(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 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 Iterator<To> getAll(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 Map<From,To>
    
    Overrides:
    
    hashCode in class Object
  - isEmpty
```
public boolean isEmpty()
```
    Answer true if the map is empty of key-value mappings.
    
    Specified by:
    
    isEmpty in interface Map<From,To>
    
    Returns:
    
    True if there are no entries.
  - keySet
```
public Set<From> keySet()
```
    Answer a set of the keys in this map
    
    Specified by:
    
    keySet in interface 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 Map<From,To>
    
    Parameters:
    
    key - The key object
    
    value - The value object
    
    Returns:
    
    Null.
  - putAll
```
public void putAll(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 Map<From,To>
    
    Parameters:
    
    m - The map whose contents are to be copied into this map
  - remove
```
public To remove(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 Map<From,To>
    
    Parameters:
    
    key - All associations with this key will be removed
    
    Returns:
    
    null
  - remove
```
public boolean remove(Object key,
                      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 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 Map<From,To>
    
    Returns:
    
    The number of key-value pairs.
  - values
```
public 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 Map<From,To>
    
    Returns:
    
    A set of the values contained in this map.
  - toString
```
public String toString()
```
    Answer a string representation of this map. This can be quite a long string for large maps.
    
    Overrides:
    
    toString in class Object

Class OneToManyMap<From,To>

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Constructor Detail

OneToManyMap

OneToManyMap

Method Detail

clear

containsKey

containsValue

contains

entrySet

equals

get

getAll

hashCode

isEmpty

keySet

put

putAll

remove

remove

size

values

toString