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Class java.util.ArrayMap

java.lang.Object
    |
    +----java.util.AbstractMap
            |
            +----java.util.ArrayMap

public class ArrayMap

extends AbstractMap

implements Map, Cloneable, Serializable

This class guarantees that the Map will be in key-insertion order. If a new value is associated with a key already in the Map, the order is unaffected. If a key-value mapping is removed and a mapping for the same key is inserted at a later time, the mapping goes to the end of the Map, just like any other key-insertion.

Note that this implementation is not synchronized. If multiple threads access an ArrayMap concurrently, and at least one of the threads modifies the ArrayMap structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more mappings; merely changing the value associated with a key that is already contained in the Table is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the ArrayMap. If no such object exists, the ArrayMap should be "wrapped" using the Collections.synchronizedSet method. This is best done at creation time, to prevent accidental unsynchronized access to the ArrayMap:

	Map m = Collections.synchronizedMap(new ArrayMap(...));
 

The Iterators returned by the iterator methods of the Collections returned by all of ArrayMap's "collection view methods" are fail-fast: if the ArrayMap is structurally modified at any time after the Iterator is created, in any way except through the Iterator's own remove or add methods, the Iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the Iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Since:

JDK1.2

See Also:

Collection, Map, HashMap, TreeMap, Hashtable, Collections.synchronizedMap, ArrayList

ArrayMap()

Constructs a new, empty ArrayMap; the backing ArrayList has default initial capacity and capacity increment.

ArrayMap(int)

Constructs a new, empty ArrayMap; the backing ArrayList has the specified initial capacity and default capacity increment.

ArrayMap(Map)

Constructs a new ArrayMap containing the mappings in the specified Map.

clone()

Creates a shallow copy of this ArrayMap.

entries()

Returns a Collection view of the mappings contained in this ArrayMap.

put(Object, Object)

Associates the specified value with the specified key in this Map (optional operation).

public ArrayMap()

Constructs a new, empty ArrayMap; the backing ArrayList has default initial capacity and capacity increment.

public ArrayMap(Map t)

Constructs a new ArrayMap containing the mappings in the specified Map. The backing ArrayList has default initial capacity and capacity increment.

Throws: NullPointerException

the specified Map is null.

public ArrayMap(int initialCapacity)

Constructs a new, empty ArrayMap; the backing ArrayList has the specified initial capacity and default capacity increment.

Parameters:

initialCapacity - the initial capacity of the ArrayList.

public Collection entries()

Returns a Collection view of the mappings contained in this ArrayMap. Each element in the returned collection is a Map.Entry. The Collection is backed by the ArrayMap, so changes to the ArrayMap are reflected in the Collection, and vice-versa. The Collection supports element removal, which removes the corresponding mapping from the ArrayMap, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Overrides:

entries in class AbstractMap

See Also:

Map.Entry

public Object put(Object key,
                  Object value)

Associates the specified value with the specified key in this Map (optional operation). If the Map previously contained a mapping for this key, the old value is replaced.

Parameters:

key - key with which the specified value is to be associated.

value - value to be associated with the specified key.

Returns:

previous value associated with specified key, or null if there was no entry for key. (A null return can also indicate that the Map previously associated null with the specified key.)

Overrides:

put in class AbstractMap

public Object clone()

Creates a shallow copy of this ArrayMap. The keys and values themselves are not cloned.

Overrides:

clone in class Object

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