Field Detail

• EMPTY_BAG

  public static final Bag EMPTY_BAG

  An empty unmodifiable bag.

• EMPTY_SORTED_BAG

  public static final Bag EMPTY_SORTED_BAG

  An empty unmodifiable sorted bag.

Constructor Detail

• BagUtils

  public BagUtils()

  Instantiation of BagUtils is not intended or required. However, some tools require an instance to operate.

Method Detail

• synchronizedBag

  public static Bag synchronizedBag​(Bag bag)

  Returns a synchronized (thread-safe) bag backed by the given bag. In order to guarantee serial access, it is critical that all access to the backing bag is accomplished through the returned bag.

  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

• unmodifiableBag

  public static Bag unmodifiableBag​(Bag bag)

  Returns an unmodifiable view of the given bag. Any modification attempts to the returned bag will raise an UnsupportedOperationException.

  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

• predicatedBag

  public static Bag predicatedBag​(Bag bag,
                                  Predicate predicate)

  Returns a predicated (validating) bag backed by the given 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

• typedBag

  public static Bag typedBag​(Bag bag,
                             Class type)

  Returns a typed bag backed by the given 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

• transformedBag

  public static Bag transformedBag​(Bag bag,
                                   Transformer transformer)

  Returns a transformed bag backed by the given bag.

  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

• synchronizedSortedBag

  public static SortedBag synchronizedSortedBag​(SortedBag bag)

  Returns a synchronized (thread-safe) sorted bag backed by the given sorted bag. In order to guarantee serial access, it is critical that all access to the backing bag is accomplished through the returned bag.

  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

• unmodifiableSortedBag

  public static SortedBag unmodifiableSortedBag​(SortedBag bag)

  Returns an unmodifiable view of the given sorted bag. Any modification attempts to the returned bag will raise an UnsupportedOperationException.

  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

• predicatedSortedBag

  public static SortedBag predicatedSortedBag​(SortedBag bag,
                                              Predicate predicate)

  Returns a predicated (validating) sorted bag backed by 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 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

• typedSortedBag

  public static SortedBag typedSortedBag​(SortedBag bag,
                                         Class type)

  Returns a typed sorted bag backed by the given 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

• transformedSortedBag

  public static SortedBag transformedSortedBag​(SortedBag bag,
                                               Transformer transformer)

  Returns a transformed sorted bag backed by the given bag.

  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