of the new collections APIs have been introduced in Java 6.0. These are:
It is used to represent Double ended queue. With the help of this collection
we can add or remove elements at both the ends. Deque implementation can be
used as Stack (Last in first out) or Queue (First in First Out).
There are two methods in Deque, which are used for insertion, retrieval and
removal of elements. One returns status or special value for each operation
and the other will throw exception if it fails in an operation.
It is similar to Deque but with added functionality.When we try
to insert an element in a BlockingDeque and if the BlockingDeque is already
full then the element can wait till the space becomes available to insert an
element. There are four methods available for BlockingDeque.
Methods throws exception
Methods that times out (Waits for a given time for space to
Methods that blocks (Waits indefinitely for space to
Methods returns special value
It is usedto return the closest matches of elements. For instance if
we want retrieve the element, which is immediately greater than, or lower
than element 20 or if we want to retrieve all elements greater than or lower
than 35 from sorted set elements [10,20,35,5] we can use NavigableSet
methods that becomes just a method call. ConcurrentSkipListSet is one
of the class that implements NavigableSet.
In NavigableSet, methods use to return values, but in NaviagableMap
methods used to return the key,value pair. ConcurrentSkipListMap is
the one of the class which implements NaviagableMap
Some of the new Classes are:
ArrayDeque is a class that implements Deque. If used as a stack or
linked list, it performs much faster than before. It is neither thread safe
nor has capacity restrictions.
Itimplements BlockingDeque. Maximum capacity can be specified by
using BlockingDeque interface. However the maximum capacity will be
Integer.MAX_VALUE if not specified.
ConcurrentSkipListSet is one of the class that implements NavigableSet.
It is usedto return the closest matches of elements.
ConcurrentSkipListMap is the one of the class which implements
NaviagableMap. In NavigableSet, methods use to return values.
The key value pair of one single entry in a Map is held by the instance
of this class. Moreover it is a static nested class nested inside abstractMap
AbstractMap.SimpleImmutableEntry: This class is similar to AbstractMap.SimpleEntry class
however it has one difference that it throws the exception UnsupportedOperationException when we try to set a value while AbstractMap.SimpleEntry
Updated Classes in Java 6.0
To implement the new interfaces we modify some
classes like TreeSet is modified to implement NavigableSet, LinkedList
is modified to implement Deque, TreeMap is modified to implement
NavigableMap etc. Some of the new methods like newSetFromMap and asLifoQueue
have been added to Collections 2.
the bi- directional traversal has become easier with java6.0 collections. We can
even retrieve elements as desired.
June 21, 2012
Prog in LinkedHashMap
There are two LinkedHashMap objects are there and we store values to these two
objects ,and get all keys from these objects and store in List
For better understanding
Map a=new LinkedHashMap();
Map b=new LinkedHashMap();
I want OutPut As: 1 2 3 4