# Class PredicatedMap<K,V>

java.lang.Object
org.apache.commons.collections4.map.AbstractIterableMap<K,V>
org.apache.commons.collections4.map.AbstractMapDecorator<K,V>
org.apache.commons.collections4.map.PredicatedMap<K,V>

Type Parameters:
  `K` - the type of the keys in this map
  `V` - the type of the values in this map

All Implemented Interfaces:
  `Serializable`, `Map<K,V>`, `Get<K,V>`, `IterableGet<K,V>`, `IterableMap<K,V>`, `Put<K,V>`

Direct Known Subclasses:
  `PredicatedSortedMap`

public class PredicatedMap<K,V> extends AbstractMapDecorator<K,V> implements Serializable
Decorates another `Map` to validate that additions match a specified predicate.

This map exists to provide validation for the decorated map. It is normally created to decorate an empty map. If an object cannot be added to the map, an IllegalArgumentException is thrown.

One usage would be to ensure that no null keys are added to the map.

    Map map = PredicatedSet.decorate(new HashMap(), NotNullPredicate.INSTANCE, null);

Note that PredicatedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using `Collections.synchronizedMap(Map)`. This class may throw exceptions when accessed by concurrent threads without synchronization.

This class is Serializable from Commons Collections 3.1.

Since:
  3.0
See Also:
  - Serialized Form

- ## Nested Class Summary

  ### Nested classes/interfaces inherited from interface java.util.Map

  `Map.Entry<K,V>`

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected final Predicate<? super K>`
  `keyPredicate`
  The key predicate to use
  `protected final Predicate<? super V>`
  `valuePredicate`
  The value predicate to use

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `PredicatedMap(Map<K,V> map, Predicate<? super K> keyPredicate, Predicate<? super V> valuePredicate)`
  Constructor that wraps (not copies).

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected V`
  `checkSetValue(V value)`
  Override to validate an object set into the map via `setValue`.
  `Set<Map.Entry<K,V>>`
  `entrySet()`
  Gets a set view of the mappings contained in this map.
  `protected boolean`
  `isSetValueChecking()`
  Override to only return true when there is a value transformer.
  `static <K, V> PredicatedMap<K,V>`
  `predicatedMap(Map<K,V> map, Predicate<? super K> keyPredicate, Predicate<? super V> valuePredicate)`
  Factory method to create a predicated (validating) map.
  `V`
  `put(K key, V value)`
  Associates the specified value with the specified key in this map.
  `void`
  `putAll(Map<? extends K,? extends V> mapToCopy)`
  Copies all of the mappings from the specified map to this map.
  `protected void`
  `validate(K key, V value)`
  Validates a key value pair.

  ### Methods inherited from class org.apache.commons.collections4.map.AbstractMapDecorator

  `clear, containsKey, containsValue, decorated, equals, get, hashCode, isEmpty, keySet, remove, size, toString, values`

  ### Methods inherited from class org.apache.commons.collections4.map.AbstractIterableMap

  `mapIterator`

  ### Methods inherited from class java.lang.Object

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

  ### Methods inherited from interface java.util.Map

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

- ## Field Details

  - ### keyPredicate

    protected final Predicate<? super K> keyPredicate
    The key predicate to use

  - ### valuePredicate

    protected final Predicate<? super V> valuePredicate
    The value predicate to use

- ## Constructor Details

  - ### PredicatedMap

    protected PredicatedMap(Map<K,V> map, Predicate<? super K> keyPredicate, Predicate<? super V> valuePredicate)
    Constructor that wraps (not copies).
    Parameters:
      `map` - the map to decorate, must not be null
      `keyPredicate` - the predicate to validate the keys, null means no check
      `valuePredicate` - the predicate to validate to values, null means no check
    Throws:
      `NullPointerException` - if the map is null

- ## Method Details

  - ### predicatedMap

    public static <K, V> PredicatedMap<K,V> predicatedMap(Map<K,V> map, Predicate<? super K> keyPredicate, Predicate<? super V> valuePredicate)
    Factory method to create a predicated (validating) map.

    If there are any elements already in the list being decorated, they are validated.

    Type Parameters:
      `K` - the key type
      `V` - the value type
    Parameters:
      `map` - the map to decorate, must not be null
      `keyPredicate` - the predicate to validate the keys, null means no check
      `valuePredicate` - the predicate to validate to values, null means no check
    Returns:
      a new predicated map
    Throws:
      `NullPointerException` - if the map is null
    Since:
      4.0

  - ### checkSetValue

    protected V checkSetValue(V value)
    Override to validate an object set into the map via `setValue`.
    Parameters:
      `value` - the value to validate
    Returns:
      the value itself
    Throws:
      `IllegalArgumentException` - if invalid
    Since:
      3.1

  - ### isSetValueChecking

    protected boolean isSetValueChecking()
    Override to only return true when there is a value transformer.
    Returns:
      true if a value predicate is in use
    Since:
      3.1

  - ### put

    public V put(K key, V value)
    Description copied from interface: `Put`
    Associates the specified value with the specified key in this map.

    Note that the return type is Object, rather than V as in the Map interface. See the class Javadoc for further info.

    Specified by:
      `put` in interface `Map<K,V>`
    Specified by:
      `put` in interface `Put<K,V>`
    Overrides:
      `put` in class `AbstractMapDecorator<K,V>`
    Parameters:
      `key` - key with which the specified value is to be associated
      `value` - value to be associated with the specified key
    Returns:
      the previous value associated with `key`, or `null` if there was no mapping for `key`. (A `null` return can also indicate that the map previously associated `null` with `key`, if the implementation supports `null` values.)
    See Also:
      - `Map.put(Object, Object)`

  - ### putAll

    public void putAll(Map<? extends K,? extends V> mapToCopy)
    Description copied from interface: `Put`
    Copies all of the mappings from the specified map to this map.
    Specified by:
      `putAll` in interface `Map<K,V>`
    Specified by:
      `putAll` in interface `Put<K,V>`
    Overrides:
      `putAll` in class `AbstractMapDecorator<K,V>`
    Parameters:
      `mapToCopy` - mappings to be stored in this map
    See Also:
      - `Map.putAll(Map)`

  - ### validate

    protected void validate(K key, V value)
    Validates a key value pair.
    Parameters:
      `key` - the key to validate
      `value` - the value to validate
    Throws:
      `IllegalArgumentException` - if invalid

  - ### entrySet

    public Set<Map.Entry<K,V>> entrySet()
    Description copied from interface: `Get`
    Gets a set view of the mappings contained in this map.
    Specified by:
      `entrySet` in interface `Get<K,V>`
    Specified by:
      `entrySet` in interface `Map<K,V>`
    Overrides:
      `entrySet` in class `AbstractMapDecorator<K,V>`
    Returns:
      a set view of the mappings contained in this map.
    See Also:
      - `Map.entrySet()`