The
Collection interface provides support for
the implementation of a mathematical bag
- an unordered collection of objects that
may contain duplicates.
I
am trying to store an object using a key
in a Hashtable. And some other object
already exists in that location, then
what will happen? The existing object
will be overwritten? Or the new object
will be stored elsewhere?
A:
The
existing object will be overwritten and
thus it will be lost.
What
is the difference between the size and
capacity of a Vector?
A:
The
size is the number of elements actually
stored in the vector, while capacity is
the maximum number of elements it can store
at a given instance of time.
An enumeration is an interface containing
methods for accessing the underlying data
structure from which the enumeration is
obtained. It is a construct which collection
classes return when you request a collection
of all the objects stored in the collection.
It allows sequential access to all the elements
stored in the collection.
Considering
the basic properties of Vector and ArrayList,
where will you use Vector and where will
you use ArrayList?
A:
The
basic difference between a Vector and an
ArrayList is that, vector is synchronized
while ArrayList is not. Thus whenever there
is a possibility of multiple threads accessing
the same instance, one should use Vector.
While if not multiple threads are going
to access the same instance then use ArrayList.
Non synchronized data structure will give
better performance than the synchronized
one.