AbstractHashedMap (Apache Commons Collections 3.2.2 API)

java.lang.Object
- java.util.AbstractMap
- - org.apache.commons.collections.map.AbstractHashedMap

All Implemented Interfaces:

Map, IterableMap

Direct Known Subclasses:

AbstractLinkedMap, AbstractReferenceMap, CaseInsensitiveMap, HashedMap, IdentityMap
```
public class AbstractHashedMap
extends AbstractMap
implements IterableMap
```
An abstract implementation of a hash-based map which provides numerous points for subclasses to override.
This class implements all the features necessary for a subclass hash-based map. Key-value entries are stored in instances of the HashEntry class, which can be overridden and replaced. The iterators can similarly be replaced, without the need to replace the KeySet, EntrySet and Values view classes.
Overridable methods are provided to change the default hashing behaviour, and to change how entries are added to and removed from the map. Hopefully, all you need for unusual subclasses is here.
NOTE: From Commons Collections 3.1 this class extends AbstractMap. This is to provide backwards compatibility for ReferenceMap between v3.0 and v3.1. This extends clause will be removed in v4.0.

Since:

Commons Collections 3.0

Version:

$Revision: 972404 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

java util HashMap, Stephen Colebourne, Christian Siefkes

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`protected static class`	`AbstractHashedMap.EntrySet` EntrySet implementation.
`protected static class`	`AbstractHashedMap.EntrySetIterator` EntrySet iterator.
`protected static class`	`AbstractHashedMap.HashEntry` HashEntry used to store the data.
`protected static class`	`AbstractHashedMap.HashIterator` Base Iterator
`protected static class`	`AbstractHashedMap.HashMapIterator` MapIterator implementation.
`protected static class`	`AbstractHashedMap.KeySet` KeySet implementation.
`protected static class`	`AbstractHashedMap.KeySetIterator` KeySet iterator.
`protected static class`	`AbstractHashedMap.Values` Values implementation.
`protected static class`	`AbstractHashedMap.ValuesIterator` Values iterator.

Nested classes/interfaces inherited from class java.util.AbstractMap
AbstractMap.SimpleEntry, AbstractMap.SimpleImmutableEntry

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

Field Summary

Fields
Modifier and Type	Field and Description
`protected AbstractHashedMap.HashEntry[]`	`data` Map entries
`protected static int`	`DEFAULT_CAPACITY` The default capacity to use
`protected static float`	`DEFAULT_LOAD_FACTOR` The default load factor to use
`protected static int`	`DEFAULT_THRESHOLD` The default threshold to use
`protected AbstractHashedMap.EntrySet`	`entrySet` Entry set
`protected static String`	`GETKEY_INVALID`
`protected static String`	`GETVALUE_INVALID`
`protected AbstractHashedMap.KeySet`	`keySet` Key set
`protected float`	`loadFactor` Load factor, normally 0.75
`protected static int`	`MAXIMUM_CAPACITY` The maximum capacity allowed
`protected int`	`modCount` Modification count for iterators
`protected static String`	`NO_NEXT_ENTRY`
`protected static String`	`NO_PREVIOUS_ENTRY`
`protected static Object`	`NULL` An object for masking null
`protected static String`	`REMOVE_INVALID`
`protected static String`	`SETVALUE_INVALID`
`protected int`	`size` The size of the map
`protected int`	`threshold` Size at which to rehash
`protected AbstractHashedMap.Values`	`values` Values

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`AbstractHashedMap()` Constructor only used in deserialization, do not use otherwise.
`protected`	`AbstractHashedMap(int initialCapacity)` Constructs a new, empty map with the specified initial capacity and default load factor.
`protected`	`AbstractHashedMap(int initialCapacity, float loadFactor)` Constructs a new, empty map with the specified initial capacity and load factor.
`protected`	`AbstractHashedMap(int initialCapacity, float loadFactor, int threshold)` Constructor which performs no validation on the passed in parameters.
`protected`	`AbstractHashedMap(Map map)` Constructor copying elements from another map.

Method Summary

Methods
Modifier and Type	Method and Description
`protected void`	`addEntry(AbstractHashedMap.HashEntry entry, int hashIndex)` Adds an entry into this map.
`protected void`	`addMapping(int hashIndex, int hashCode, Object key, Object value)` Adds a new key-value mapping into this map.
`protected int`	`calculateNewCapacity(int proposedCapacity)` Calculates the new capacity of the map.
`protected int`	`calculateThreshold(int newCapacity, float factor)` Calculates the new threshold of the map, where it will be resized.
`protected void`	`checkCapacity()` Checks the capacity of the map and enlarges it if necessary.
`void`	`clear()` Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues.
`protected Object`	`clone()` Clones the map without cloning the keys or values.
`boolean`	`containsKey(Object key)` Checks whether the map contains the specified key.
`boolean`	`containsValue(Object value)` Checks whether the map contains the specified value.
`protected Object`	`convertKey(Object key)` Converts input keys to another object for storage in the map.
`protected AbstractHashedMap.HashEntry`	`createEntry(AbstractHashedMap.HashEntry next, int hashCode, Object key, Object value)` Creates an entry to store the key-value data.
`protected Iterator`	`createEntrySetIterator()` Creates an entry set iterator.
`protected Iterator`	`createKeySetIterator()` Creates a key set iterator.
`protected Iterator`	`createValuesIterator()` Creates a values iterator.
`protected void`	`destroyEntry(AbstractHashedMap.HashEntry entry)` Kills an entry ready for the garbage collector.
`protected void`	`doReadObject(ObjectInputStream in)` Reads the map data from the stream.
`protected void`	`doWriteObject(ObjectOutputStream out)` Writes the map data to the stream.
`protected void`	`ensureCapacity(int newCapacity)` Changes the size of the data structure to the capacity proposed.
`protected int`	`entryHashCode(AbstractHashedMap.HashEntry entry)` Gets the `hashCode` field from a `HashEntry`.
`protected Object`	`entryKey(AbstractHashedMap.HashEntry entry)` Gets the `key` field from a `HashEntry`.
`protected AbstractHashedMap.HashEntry`	`entryNext(AbstractHashedMap.HashEntry entry)` Gets the `next` field from a `HashEntry`.
`Set`	`entrySet()` Gets the entrySet view of the map.
`protected Object`	`entryValue(AbstractHashedMap.HashEntry entry)` Gets the `value` field from a `HashEntry`.
`boolean`	`equals(Object obj)` Compares this map with another.
`Object`	`get(Object key)` Gets the value mapped to the key specified.
`protected AbstractHashedMap.HashEntry`	`getEntry(Object key)` Gets the entry mapped to the key specified.
`protected int`	`hash(Object key)` Gets the hash code for the key specified.
`int`	`hashCode()` Gets the standard Map hashCode.
`protected int`	`hashIndex(int hashCode, int dataSize)` Gets the index into the data storage for the hashCode specified.
`protected void`	`init()` Initialise subclasses during construction, cloning or deserialization.
`boolean`	`isEmpty()` Checks whether the map is currently empty.
`protected boolean`	`isEqualKey(Object key1, Object key2)` Compares two keys, in internal converted form, to see if they are equal.
`protected boolean`	`isEqualValue(Object value1, Object value2)` Compares two values, in external form, to see if they are equal.
`Set`	`keySet()` Gets the keySet view of the map.
`MapIterator`	`mapIterator()` Gets an iterator over the map.
`Object`	`put(Object key, Object value)` Puts a key-value mapping into this map.
`void`	`putAll(Map map)` Puts all the values from the specified map into this map.
`Object`	`remove(Object key)` Removes the specified mapping from this map.
`protected void`	`removeEntry(AbstractHashedMap.HashEntry entry, int hashIndex, AbstractHashedMap.HashEntry previous)` Removes an entry from the chain stored in a particular index.
`protected void`	`removeMapping(AbstractHashedMap.HashEntry entry, int hashIndex, AbstractHashedMap.HashEntry previous)` Removes a mapping from the map.
`protected void`	`reuseEntry(AbstractHashedMap.HashEntry entry, int hashIndex, int hashCode, Object key, Object value)` Reuses an existing key-value mapping, storing completely new data.
`int`	`size()` Gets the size of the map.
`String`	`toString()` Gets the map as a String.
`protected void`	`updateEntry(AbstractHashedMap.HashEntry entry, Object newValue)` Updates an existing key-value mapping to change the value.
`Collection`	`values()` Gets the values view of the map.

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - NO_NEXT_ENTRY
```
protected static final String NO_NEXT_ENTRY
```
    See Also:
    Constant Field Values
  - NO_PREVIOUS_ENTRY
```
protected static final String NO_PREVIOUS_ENTRY
```
    See Also:
    Constant Field Values
  - REMOVE_INVALID
```
protected static final String REMOVE_INVALID
```
    See Also:
    Constant Field Values
  - GETKEY_INVALID
```
protected static final String GETKEY_INVALID
```
    See Also:
    Constant Field Values
  - GETVALUE_INVALID
```
protected static final String GETVALUE_INVALID
```
    See Also:
    Constant Field Values
  - SETVALUE_INVALID
```
protected static final String SETVALUE_INVALID
```
    See Also:
    Constant Field Values
  - DEFAULT_CAPACITY
```
protected static final int DEFAULT_CAPACITY
```
    The default capacity to use
    
    See Also:
    Constant Field Values
  - DEFAULT_THRESHOLD
```
protected static final int DEFAULT_THRESHOLD
```
    The default threshold to use
    
    See Also:
    Constant Field Values
  - DEFAULT_LOAD_FACTOR
```
protected static final float DEFAULT_LOAD_FACTOR
```
    The default load factor to use
    
    See Also:
    Constant Field Values
  - MAXIMUM_CAPACITY
```
protected static final int MAXIMUM_CAPACITY
```
    The maximum capacity allowed
    
    See Also:
    Constant Field Values
  - NULL
```
protected static final Object NULL
```
    An object for masking null
  - loadFactor
```
protected transient float loadFactor
```
    Load factor, normally 0.75
  - size
```
protected transient int size
```
    The size of the map
  - data
```
protected transient AbstractHashedMap.HashEntry[] data
```
    Map entries
  - threshold
```
protected transient int threshold
```
    Size at which to rehash
  - modCount
```
protected transient int modCount
```
    Modification count for iterators
  - entrySet
```
protected transient AbstractHashedMap.EntrySet entrySet
```
    Entry set
  - keySet
```
protected transient AbstractHashedMap.KeySet keySet
```
    Key set
  - values
```
protected transient AbstractHashedMap.Values values
```
    Values
- Constructor Detail
  - AbstractHashedMap
```
protected AbstractHashedMap()
```
    Constructor only used in deserialization, do not use otherwise.
  - AbstractHashedMap
```
protected AbstractHashedMap(int initialCapacity,
                 float loadFactor,
                 int threshold)
```
    Constructor which performs no validation on the passed in parameters.
    
    Parameters:
    initialCapacity - the initial capacity, must be a power of two
    loadFactor - the load factor, must be > 0.0f and generally < 1.0f
    threshold - the threshold, must be sensible
  - AbstractHashedMap
```
protected AbstractHashedMap(int initialCapacity)
```
    Constructs a new, empty map with the specified initial capacity and default load factor.
    
    Parameters:
    initialCapacity - the initial capacity
    
    Throws:
    
    IllegalArgumentException - if the initial capacity is less than one
  - AbstractHashedMap
```
protected AbstractHashedMap(int initialCapacity,
                 float loadFactor)
```
    Constructs a new, empty map with the specified initial capacity and load factor.
    
    Parameters:
    initialCapacity - the initial capacity
    loadFactor - the load factor
    
    Throws:
    
    IllegalArgumentException - if the initial capacity is less than one
    
    IllegalArgumentException - if the load factor is less than or equal to zero
  - AbstractHashedMap
```
protected AbstractHashedMap(Map map)
```
    Constructor copying elements from another map.
    
    Parameters:
    map - the map to copy
    
    Throws:
    
    NullPointerException - if the map is null
- Method Detail
  - init
```
protected void init()
```
    Initialise subclasses during construction, cloning or deserialization.
  - get
```
public Object get(Object key)
```
    Gets the value mapped to the key specified.
    
    Specified by:
    
    get in interface Map
    
    Overrides:
    
    get in class AbstractMap
    
    Parameters:
    key - the key
    
    Returns:
    the mapped value, null if no match
  - size
```
public int size()
```
    Gets the size of the map.
    
    Specified by:
    
    size in interface Map
    
    Overrides:
    
    size in class AbstractMap
    
    Returns:
    the size
  - isEmpty
```
public boolean isEmpty()
```
    Checks whether the map is currently empty.
    
    Specified by:
    
    isEmpty in interface Map
    
    Overrides:
    
    isEmpty in class AbstractMap
    
    Returns:
    true if the map is currently size zero
  - containsKey
```
public boolean containsKey(Object key)
```
    Checks whether the map contains the specified key.
    
    Specified by:
    
    containsKey in interface Map
    
    Overrides:
    
    containsKey in class AbstractMap
    
    Parameters:
    key - the key to search for
    
    Returns:
    true if the map contains the key
  - containsValue
```
public boolean containsValue(Object value)
```
    Checks whether the map contains the specified value.
    
    Specified by:
    
    containsValue in interface Map
    
    Overrides:
    
    containsValue in class AbstractMap
    
    Parameters:
    value - the value to search for
    
    Returns:
    true if the map contains the value
  - put
```
public Object put(Object key,
         Object value)
```
    Puts a key-value mapping into this map.
    
    Specified by:
    
    put in interface Map
    
    Overrides:
    
    put in class AbstractMap
    
    Parameters:
    key - the key to add
    value - the value to add
    
    Returns:
    the value previously mapped to this key, null if none
  - putAll
```
public void putAll(Map map)
```
    Puts all the values from the specified map into this map.
    This implementation iterates around the specified map and uses put(Object, Object).
    
    Specified by:
    
    putAll in interface Map
    
    Overrides:
    
    putAll in class AbstractMap
    
    Parameters:
    map - the map to add
    
    Throws:
    
    NullPointerException - if the map is null
  - remove
```
public Object remove(Object key)
```
    Removes the specified mapping from this map.
    
    Specified by:
    
    remove in interface Map
    
    Overrides:
    
    remove in class AbstractMap
    
    Parameters:
    key - the mapping to remove
    
    Returns:
    the value mapped to the removed key, null if key not in map
  - clear
```
public void clear()
```
    Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues.
    
    Specified by:
    
    clear in interface Map
    
    Overrides:
    
    clear in class AbstractMap
  - convertKey
```
protected Object convertKey(Object key)
```
    Converts input keys to another object for storage in the map. This implementation masks nulls. Subclasses can override this to perform alternate key conversions.
    The reverse conversion can be changed, if required, by overriding the getKey() method in the hash entry.
    
    Parameters:
    key - the key convert
    
    Returns:
    the converted key
  - hash
```
protected int hash(Object key)
```
    Gets the hash code for the key specified. This implementation uses the additional hashing routine from JDK1.4. Subclasses can override this to return alternate hash codes.
    
    Parameters:
    key - the key to get a hash code for
    
    Returns:
    the hash code
  - isEqualKey
```
protected boolean isEqualKey(Object key1,
                 Object key2)
```
    Compares two keys, in internal converted form, to see if they are equal. This implementation uses the equals method and assumes neither key is null. Subclasses can override this to match differently.
    
    Parameters:
    key1 - the first key to compare passed in from outside
    key2 - the second key extracted from the entry via entry.key
    
    Returns:
    true if equal
  - isEqualValue
```
protected boolean isEqualValue(Object value1,
                   Object value2)
```
    Compares two values, in external form, to see if they are equal. This implementation uses the equals method and assumes neither value is null. Subclasses can override this to match differently.
    
    Parameters:
    value1 - the first value to compare passed in from outside
    value2 - the second value extracted from the entry via getValue()
    
    Returns:
    true if equal
  - hashIndex
```
protected int hashIndex(int hashCode,
            int dataSize)
```
    Gets the index into the data storage for the hashCode specified. This implementation uses the least significant bits of the hashCode. Subclasses can override this to return alternate bucketing.
    
    Parameters:
    hashCode - the hash code to use
    dataSize - the size of the data to pick a bucket from
    
    Returns:
    the bucket index
  - getEntry
```
protected AbstractHashedMap.HashEntry getEntry(Object key)
```
    Gets the entry mapped to the key specified.
    This method exists for subclasses that may need to perform a multi-step process accessing the entry. The public methods in this class don't use this method to gain a small performance boost.
    
    Parameters:
    key - the key
    
    Returns:
    the entry, null if no match
  - updateEntry
```
protected void updateEntry(AbstractHashedMap.HashEntry entry,
               Object newValue)
```
    Updates an existing key-value mapping to change the value.
    This implementation calls setValue() on the entry. Subclasses could override to handle changes to the map.
    
    Parameters:
    entry - the entry to update
    newValue - the new value to store
  - reuseEntry
```
protected void reuseEntry(AbstractHashedMap.HashEntry entry,
              int hashIndex,
              int hashCode,
              Object key,
              Object value)
```
    Reuses an existing key-value mapping, storing completely new data.
    This implementation sets all the data fields on the entry. Subclasses could populate additional entry fields.
    
    Parameters:
    entry - the entry to update, not null
    hashIndex - the index in the data array
    hashCode - the hash code of the key to add
    key - the key to add
    value - the value to add
  - addMapping
```
protected void addMapping(int hashIndex,
              int hashCode,
              Object key,
              Object value)
```
    Adds a new key-value mapping into this map.
    This implementation calls createEntry(), addEntry() and checkCapacity(). It also handles changes to modCount and size. Subclasses could override to fully control adds to the map.
    
    Parameters:
    hashIndex - the index into the data array to store at
    hashCode - the hash code of the key to add
    key - the key to add
    value - the value to add
  - createEntry
```
protected AbstractHashedMap.HashEntry createEntry(AbstractHashedMap.HashEntry next,
                                      int hashCode,
                                      Object key,
                                      Object value)
```
    Creates an entry to store the key-value data.
    This implementation creates a new HashEntry instance. Subclasses can override this to return a different storage class, or implement caching.
    
    Parameters:
    next - the next entry in sequence
    hashCode - the hash code to use
    key - the key to store
    value - the value to store
    
    Returns:
    the newly created entry
  - addEntry
```
protected void addEntry(AbstractHashedMap.HashEntry entry,
            int hashIndex)
```
    Adds an entry into this map.
    This implementation adds the entry to the data storage table. Subclasses could override to handle changes to the map.
    
    Parameters:
    entry - the entry to add
    hashIndex - the index into the data array to store at
  - removeMapping
```
protected void removeMapping(AbstractHashedMap.HashEntry entry,
                 int hashIndex,
                 AbstractHashedMap.HashEntry previous)
```
    Removes a mapping from the map.
    This implementation calls removeEntry() and destroyEntry(). It also handles changes to modCount and size. Subclasses could override to fully control removals from the map.
    
    Parameters:
    entry - the entry to remove
    hashIndex - the index into the data structure
    previous - the previous entry in the chain
  - removeEntry
```
protected void removeEntry(AbstractHashedMap.HashEntry entry,
               int hashIndex,
               AbstractHashedMap.HashEntry previous)
```
    Removes an entry from the chain stored in a particular index.
    This implementation removes the entry from the data storage table. The size is not updated. Subclasses could override to handle changes to the map.
    
    Parameters:
    entry - the entry to remove
    hashIndex - the index into the data structure
    previous - the previous entry in the chain
  - destroyEntry
```
protected void destroyEntry(AbstractHashedMap.HashEntry entry)
```
    Kills an entry ready for the garbage collector.
    This implementation prepares the HashEntry for garbage collection. Subclasses can override this to implement caching (override clear as well).
    
    Parameters:
    entry - the entry to destroy
  - checkCapacity
```
protected void checkCapacity()
```
    Checks the capacity of the map and enlarges it if necessary.
    This implementation uses the threshold to check if the map needs enlarging
  - ensureCapacity
```
protected void ensureCapacity(int newCapacity)
```
    Changes the size of the data structure to the capacity proposed.
    
    Parameters:
    newCapacity - the new capacity of the array (a power of two, less or equal to max)
  - calculateNewCapacity
```
protected int calculateNewCapacity(int proposedCapacity)
```
    Calculates the new capacity of the map. This implementation normalizes the capacity to a power of two.
    
    Parameters:
    proposedCapacity - the proposed capacity
    
    Returns:
    the normalized new capacity
  - calculateThreshold
```
protected int calculateThreshold(int newCapacity,
                     float factor)
```
    Calculates the new threshold of the map, where it will be resized. This implementation uses the load factor.
    
    Parameters:
    newCapacity - the new capacity
    factor - the load factor
    
    Returns:
    the new resize threshold
  - entryNext
```
protected AbstractHashedMap.HashEntry entryNext(AbstractHashedMap.HashEntry entry)
```
    Gets the next field from a HashEntry. Used in subclasses that have no visibility of the field.
    
    Parameters:
    entry - the entry to query, must not be null
    
    Returns:
    the next field of the entry
    
    Throws:
    
    NullPointerException - if the entry is null
    Since:
    
    Commons Collections 3.1
  - entryHashCode
```
protected int entryHashCode(AbstractHashedMap.HashEntry entry)
```
    Gets the hashCode field from a HashEntry. Used in subclasses that have no visibility of the field.
    
    Parameters:
    entry - the entry to query, must not be null
    
    Returns:
    the hashCode field of the entry
    
    Throws:
    
    NullPointerException - if the entry is null
    Since:
    
    Commons Collections 3.1
  - entryKey
```
protected Object entryKey(AbstractHashedMap.HashEntry entry)
```
    Gets the key field from a HashEntry. Used in subclasses that have no visibility of the field.
    
    Parameters:
    entry - the entry to query, must not be null
    
    Returns:
    the key field of the entry
    
    Throws:
    
    NullPointerException - if the entry is null
    Since:
    
    Commons Collections 3.1
  - entryValue
```
protected Object entryValue(AbstractHashedMap.HashEntry entry)
```
    Gets the value field from a HashEntry. Used in subclasses that have no visibility of the field.
    
    Parameters:
    entry - the entry to query, must not be null
    
    Returns:
    the value field of the entry
    
    Throws:
    
    NullPointerException - if the entry is null
    Since:
    
    Commons Collections 3.1
  - mapIterator
```
public MapIterator mapIterator()
```
    Gets an iterator over the map. Changes made to the iterator affect this map.
    A MapIterator returns the keys in the map. It also provides convenient methods to get the key and value, and set the value. It avoids the need to create an entrySet/keySet/values object. It also avoids creating the Map.Entry object.
    
    Specified by:
    
    mapIterator in interface IterableMap
    
    Returns:
    the map iterator
  - entrySet
```
public Set entrySet()
```
    Gets the entrySet view of the map. Changes made to the view affect this map. To simply iterate through the entries, use mapIterator().
    
    Specified by:
    
    entrySet in interface Map
    
    Specified by:
    
    entrySet in class AbstractMap
    
    Returns:
    the entrySet view
  - createEntrySetIterator
```
protected Iterator createEntrySetIterator()
```
    Creates an entry set iterator. Subclasses can override this to return iterators with different properties.
    
    Returns:
    the entrySet iterator
  - keySet
```
public Set keySet()
```
    Gets the keySet view of the map. Changes made to the view affect this map. To simply iterate through the keys, use mapIterator().
    
    Specified by:
    
    keySet in interface Map
    
    Overrides:
    
    keySet in class AbstractMap
    
    Returns:
    the keySet view
  - createKeySetIterator
```
protected Iterator createKeySetIterator()
```
    Creates a key set iterator. Subclasses can override this to return iterators with different properties.
    
    Returns:
    the keySet iterator
  - values
```
public Collection values()
```
    Gets the values view of the map. Changes made to the view affect this map. To simply iterate through the values, use mapIterator().
    
    Specified by:
    
    values in interface Map
    
    Overrides:
    
    values in class AbstractMap
    
    Returns:
    the values view
  - createValuesIterator
```
protected Iterator createValuesIterator()
```
    Creates a values iterator. Subclasses can override this to return iterators with different properties.
    
    Returns:
    the values iterator
  - doWriteObject
```
protected void doWriteObject(ObjectOutputStream out)
                      throws IOException
```
    Writes the map data to the stream. This method must be overridden if a subclass must be setup before put() is used.
    Serialization is not one of the JDK's nicest topics. Normal serialization will initialise the superclass before the subclass. Sometimes however, this isn't what you want, as in this case the put() method on read can be affected by subclass state.
    The solution adopted here is to serialize the state data of this class in this protected method. This method must be called by the writeObject() of the first serializable subclass.
    Subclasses may override if they have a specific field that must be present on read before this implementation will work. Generally, the read determines what must be serialized here, if anything.
    
    Parameters:
    out - the output stream
    
    Throws:
    
    IOException
  - doReadObject
```
protected void doReadObject(ObjectInputStream in)
                     throws IOException,
                            ClassNotFoundException
```
    Reads the map data from the stream. This method must be overridden if a subclass must be setup before put() is used.
    Serialization is not one of the JDK's nicest topics. Normal serialization will initialise the superclass before the subclass. Sometimes however, this isn't what you want, as in this case the put() method on read can be affected by subclass state.
    The solution adopted here is to deserialize the state data of this class in this protected method. This method must be called by the readObject() of the first serializable subclass.
    Subclasses may override if the subclass has a specific field that must be present before put() or calculateThreshold() will work correctly.
    
    Parameters:
    in - the input stream
    
    Throws:
    
    IOException
    
    ClassNotFoundException
  - clone
```
protected Object clone()
```
    Clones the map without cloning the keys or values.
    To implement clone(), a subclass must implement the Cloneable interface and make this method public.
    
    Overrides:
    
    clone in class AbstractMap
    
    Returns:
    a shallow clone
  - equals
```
public boolean equals(Object obj)
```
    Compares this map with another.
    
    Specified by:
    
    equals in interface Map
    
    Overrides:
    
    equals in class AbstractMap
    
    Parameters:
    obj - the object to compare to
    
    Returns:
    true if equal
  - hashCode
```
public int hashCode()
```
    Gets the standard Map hashCode.
    
    Specified by:
    
    hashCode in interface Map
    
    Overrides:
    
    hashCode in class AbstractMap
    
    Returns:
    the hash code defined in the Map interface
  - toString
```
public String toString()
```
    Gets the map as a String.
    
    Overrides:
    
    toString in class AbstractMap
    
    Returns:
    a string version of the map

Class AbstractHashedMap

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

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

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

NO_NEXT_ENTRY

NO_PREVIOUS_ENTRY

REMOVE_INVALID

GETKEY_INVALID

GETVALUE_INVALID

SETVALUE_INVALID

DEFAULT_CAPACITY

DEFAULT_THRESHOLD

DEFAULT_LOAD_FACTOR

MAXIMUM_CAPACITY

NULL

loadFactor

size

data

threshold

modCount

entrySet

keySet

values

Constructor Detail

AbstractHashedMap

AbstractHashedMap

AbstractHashedMap

AbstractHashedMap

AbstractHashedMap

Method Detail

init

get

size

isEmpty

containsKey

containsValue

put

putAll

remove

clear

convertKey

hash

isEqualKey

isEqualValue

hashIndex

getEntry

updateEntry

reuseEntry

addMapping

createEntry

addEntry

removeMapping

removeEntry

destroyEntry

checkCapacity

ensureCapacity

calculateNewCapacity

calculateThreshold

entryNext

entryHashCode

entryKey

entryValue

mapIterator

entrySet

createEntrySetIterator

keySet

createKeySetIterator

values

createValuesIterator

doWriteObject

doReadObject

clone

equals

hashCode

toString