This class consists exclusively of static methods that operate on or return
collections. It contains polymorphic algorithms that operate on
collections, "wrappers", which return a new collection backed by a
specified collection, and a few other odds and ends.
The methods of this class all throw a NullPointerException
if the collections or class objects provided to them are null.
The documentation for the polymorphic algorithms contained in this class
generally includes a brief description of the implementation. Such
descriptions should be regarded as implementation notes, rather than
parts of the specification. Implementors should feel free to
substitute other algorithms, so long as the specification itself is adhered
to. (For example, the algorithm used by sort does not have to be
a mergesort, but it does have to be stable.)
The "destructive" algorithms contained in this class, that is, the
algorithms that modify the collection on which they operate, are specified
to throw UnsupportedOperationException if the collection does not
support the appropriate mutation primitive(s), such as the set
method. These algorithms may, but are not required to, throw this
exception if an invocation would have no effect on the collection. For
example, invoking the sort method on an unmodifiable list that is
already sorted may or may not throw UnsupportedOperationException.
This class is a member of the
Java Collections Framework.