Class FixedSizeMap<K,V>
- java.lang.Object
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- org.apache.commons.collections4.map.AbstractIterableMap<K,V>
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- org.apache.commons.collections4.map.AbstractMapDecorator<K,V>
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- org.apache.commons.collections4.map.FixedSizeMap<K,V>
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- Type Parameters:
K
- the type of the keys in this mapV
- the type of the values in this map
- All Implemented Interfaces:
java.io.Serializable
,java.util.Map<K,V>
,BoundedMap<K,V>
,Get<K,V>
,IterableGet<K,V>
,IterableMap<K,V>
,Put<K,V>
public class FixedSizeMap<K,V> extends AbstractMapDecorator<K,V> implements BoundedMap<K,V>, java.io.Serializable
Decorates anotherMap
to fix the size, preventing add/remove.Any action that would change the size of the map is disallowed. The put method is allowed to change the value associated with an existing key however.
If trying to remove or clear the map, an UnsupportedOperationException is thrown. If trying to put a new mapping into the map, an IllegalArgumentException is thrown. This is because the put method can succeed if the mapping's key already exists in the map, so the put method is not always unsupported.
Note that FixedSizeMap 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
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Field Summary
Fields Modifier and Type Field Description private static long
serialVersionUID
Serialization version-
Fields inherited from class org.apache.commons.collections4.map.AbstractMapDecorator
map
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Constructor Summary
Constructors Modifier Constructor Description protected
FixedSizeMap(java.util.Map<K,V> map)
Constructor that wraps (not copies).
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
java.util.Set<java.util.Map.Entry<K,V>>
entrySet()
static <K,V>
FixedSizeMap<K,V>fixedSizeMap(java.util.Map<K,V> map)
Factory method to create a fixed size map.boolean
isFull()
Returns true if this map is full and no new elements can be added.java.util.Set<K>
keySet()
int
maxSize()
Gets the maximum size of the map (the bound).V
put(K key, V value)
Note that the return type is Object, rather than V as in the Map interface.void
putAll(java.util.Map<? extends K,? extends V> mapToCopy)
private void
readObject(java.io.ObjectInputStream in)
Read the map in using a custom routine.V
remove(java.lang.Object key)
java.util.Collection<V>
values()
private void
writeObject(java.io.ObjectOutputStream out)
Write the map out using a custom routine.-
Methods inherited from class org.apache.commons.collections4.map.AbstractMapDecorator
containsKey, containsValue, decorated, equals, get, hashCode, isEmpty, size, toString
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Methods inherited from class org.apache.commons.collections4.map.AbstractIterableMap
mapIterator
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface org.apache.commons.collections4.Get
containsKey, containsValue, get, isEmpty, size
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Methods inherited from interface org.apache.commons.collections4.IterableGet
mapIterator
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Field Detail
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serialVersionUID
private static final long serialVersionUID
Serialization version- See Also:
- Constant Field Values
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Method Detail
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fixedSizeMap
public static <K,V> FixedSizeMap<K,V> fixedSizeMap(java.util.Map<K,V> map)
Factory method to create a fixed size map.- Type Parameters:
K
- the key typeV
- the value type- Parameters:
map
- the map to decorate, must not be null- Returns:
- a new fixed size map
- Throws:
java.lang.NullPointerException
- if map is null- Since:
- 4.0
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writeObject
private void writeObject(java.io.ObjectOutputStream out) throws java.io.IOException
Write the map out using a custom routine.- Parameters:
out
- the output stream- Throws:
java.io.IOException
- if an error occurs while writing to the stream- Since:
- 3.1
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readObject
private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, java.lang.ClassNotFoundException
Read the map in using a custom routine.- Parameters:
in
- the input stream- Throws:
java.io.IOException
- if an error occurs while reading from the streamjava.lang.ClassNotFoundException
- if an object read from the stream can not be loaded- Since:
- 3.1
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put
public V put(K key, V value)
Description copied from interface:Put
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 interfacejava.util.Map<K,V>
- Specified by:
put
in interfacePut<K,V>
- Overrides:
put
in classAbstractMapDecorator<K,V>
- Parameters:
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified key- Returns:
- the previous value associated with
key
, ornull
if there was no mapping forkey
. (Anull
return can also indicate that the map previously associatednull
withkey
, if the implementation supportsnull
values.) - See Also:
Map.put(Object, Object)
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clear
public void clear()
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remove
public V remove(java.lang.Object key)
- Specified by:
remove
in interfaceGet<K,V>
- Specified by:
remove
in interfacejava.util.Map<K,V>
- Overrides:
remove
in classAbstractMapDecorator<K,V>
- Parameters:
key
- key whose mapping is to be removed from the map- Returns:
- the previous value associated with
key
, ornull
if there was no mapping forkey
. - See Also:
Map.remove(Object)
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keySet
public java.util.Set<K> keySet()
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values
public java.util.Collection<V> values()
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isFull
public boolean isFull()
Description copied from interface:BoundedMap
Returns true if this map is full and no new elements can be added.- Specified by:
isFull
in interfaceBoundedMap<K,V>
- Returns:
true
if the map is full
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maxSize
public int maxSize()
Description copied from interface:BoundedMap
Gets the maximum size of the map (the bound).- Specified by:
maxSize
in interfaceBoundedMap<K,V>
- Returns:
- the maximum number of elements the map can hold
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