org.apache.commons.collections
public class BagUtils extends Object
Since: Commons Collections 2.1
Version: $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
Field Summary | |
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static Bag | EMPTY_BAG
An empty unmodifiable bag. |
static Bag | EMPTY_SORTED_BAG
An empty unmodifiable sorted bag. |
Constructor Summary | |
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BagUtils()
Instantiation of BagUtils is not intended or required.
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Method Summary | |
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static Bag | predicatedBag(Bag bag, Predicate predicate)
Returns a predicated (validating) bag backed by the given bag.
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static SortedBag | predicatedSortedBag(SortedBag bag, Predicate predicate)
Returns a predicated (validating) sorted bag backed by the given sorted bag.
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static Bag | synchronizedBag(Bag bag)
Returns a synchronized (thread-safe) bag backed by the given bag.
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static SortedBag | synchronizedSortedBag(SortedBag bag)
Returns a synchronized (thread-safe) sorted bag backed by the given
sorted bag.
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static Bag | transformedBag(Bag bag, Transformer transformer)
Returns a transformed bag backed by the given bag.
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static SortedBag | transformedSortedBag(SortedBag bag, Transformer transformer)
Returns a transformed sorted bag backed by the given bag.
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static Bag | typedBag(Bag bag, Class type)
Returns a typed bag backed by the given bag.
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static SortedBag | typedSortedBag(SortedBag bag, Class type)
Returns a typed sorted bag backed by the given bag.
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static Bag | unmodifiableBag(Bag bag)
Returns an unmodifiable view of the given bag. |
static SortedBag | unmodifiableSortedBag(SortedBag bag)
Returns an unmodifiable view of the given sorted bag. |
Only objects that pass the test in the given predicate can be added to the bag. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original bag after invoking this method, as it is a backdoor for adding invalid objects.
Parameters: bag the bag to predicate, must not be null predicate the predicate for the bag, must not be null
Returns: a predicated bag backed by the given bag
Throws: IllegalArgumentException if the Bag or Predicate is null
Only objects that pass the test in the given predicate can be added to the bag. Trying to add an invalid object results in an IllegalArgumentException. It is important not to use the original bag after invoking this method, as it is a backdoor for adding invalid objects.
Parameters: bag the sorted bag to predicate, must not be null predicate the predicate for the bag, must not be null
Returns: a predicated bag backed by the given bag
Throws: IllegalArgumentException if the SortedBag or Predicate is null
It is imperative that the user manually synchronize on the returned bag when iterating over it:
Bag bag = BagUtils.synchronizedBag(new HashBag()); ... synchronized(bag) { Iterator i = bag.iterator(); // Must be in synchronized block while (i.hasNext()) foo(i.next()); } }Failure to follow this advice may result in non-deterministic behavior.
Parameters: bag the bag to synchronize, must not be null
Returns: a synchronized bag backed by that bag
Throws: IllegalArgumentException if the Bag is null
It is imperative that the user manually synchronize on the returned bag when iterating over it:
SortedBag bag = BagUtils.synchronizedSortedBag(new TreeBag()); ... synchronized(bag) { Iterator i = bag.iterator(); // Must be in synchronized block while (i.hasNext()) foo(i.next()); } }Failure to follow this advice may result in non-deterministic behavior.
Parameters: bag the bag to synchronize, must not be null
Returns: a synchronized bag backed by that bag
Throws: IllegalArgumentException if the SortedBag is null
Each object is passed through the transformer as it is added to the Bag. It is important not to use the original bag after invoking this method, as it is a backdoor for adding untransformed objects.
Parameters: bag the bag to predicate, must not be null transformer the transformer for the bag, must not be null
Returns: a transformed bag backed by the given bag
Throws: IllegalArgumentException if the Bag or Transformer is null
Each object is passed through the transformer as it is added to the Bag. It is important not to use the original bag after invoking this method, as it is a backdoor for adding untransformed objects.
Parameters: bag the bag to predicate, must not be null transformer the transformer for the bag, must not be null
Returns: a transformed bag backed by the given bag
Throws: IllegalArgumentException if the Bag or Transformer is null
Only objects of the specified type can be added to the bag.
Parameters: bag the bag to limit to a specific type, must not be null type the type of objects which may be added to the bag
Returns: a typed bag backed by the specified bag
Only objects of the specified type can be added to the bag.
Parameters: bag the bag to limit to a specific type, must not be null type the type of objects which may be added to the bag
Returns: a typed bag backed by the specified bag
Parameters: bag the bag whose unmodifiable view is to be returned, must not be null
Returns: an unmodifiable view of that bag
Throws: IllegalArgumentException if the Bag is null
Parameters: bag the bag whose unmodifiable view is to be returned, must not be null
Returns: an unmodifiable view of that bag
Throws: IllegalArgumentException if the SortedBag is null