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High there is little wonder Lodo.

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And welcome back.

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Let's not known about collections framework which is part of the job that you do package which encrypted

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utility classes that mainly represent sophisticated data structures.

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That is true.

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It also has other kinds of classes like the big class but many of the classes represent data structures

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.

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So these are ready to use highly efficient data structures which we can use right out of the box without

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having to implement them ourselves.

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Notice goneness collection's framework as the data that supports basically whole collection of elements

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.

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So let's go ahead and get started with the chapter.

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So for me a little bit only one data structure visuals and audio on below that are of different dimensions

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or is very powerful and it's a most fundamental data structure in any programming language but it is

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very difficult to build software using just andare as we generally how more requirements that are it

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cannot fulfill.

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For example here are some limitations so far this first one is that nobody can hold any fixed number

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of values.

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And we also know that an hour is not automatically extendable.

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That is if you want to add elements beyond the array size then it is simply not possible to do that

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.

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Adam Insearch is expensive.

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It is linear in terms of complexity on here are different kinds of requirements which we normally need

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other kinds of data structures for fulfilling those requirements.

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What I meant is that sometimes we do not how any knowledge about the number of elements that we are

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going to deal with.

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And so we need to be able to create data structures without specifying that data structure size.

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Sometimes we want that data structure to be automatically extendable when it reaches its maximum size

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which we know is not possible within.

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Sometimes like in the case of Inari be fast random access but of course with some other benefits on

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a fast random access.

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What we mean is for the UN index we should be able to extract the element of the index in a constant

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time.

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In some cases we want fast lookups.

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That is elementary search should be extremely fast like constant time and a requirement would be to

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preserve the order in which elements are added.

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That has been retrieved the elements.

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We get them back in the same order in which they were inserted and sometimes we just don't get a book

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in social order.

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Sometimes we want a data structure that can hold duplicate elements and sometimes we want a data structure

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that holds only unique elements.

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We may also want a data structure that can hold null values and sometimes we dont want the data structure

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to hold any null values.

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That is it should throw an exception if we try to add a null value.

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Sometimes you want the elements to be automatically sorted.

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And finally we sometimes want a data structure to hold key value pairs which would allow us to extract

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a value based on a given key.

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This would be supported by a hash table implementation.

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So collections framework includes different kinds of data structures that would meet one or more of

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these requirements collection's framework includes several interfaces lots of different classes which

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implement those interfaces and also a few classes that provide genetic algorithms like searching and

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sorting off different data structures.

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Unhidden according to physicists and the collections framework.

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So these are interfaces are not process and as you can see there are two distinct areas here.

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One of them has a physical collection as a root interface and the other has a map of the route into

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this collection would represent a collection of objects.

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Right.

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Motard represent a collection of key value pairs on these end of business of different implementations

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.

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So since this interfaces allow us to define common protocol we do get the benefit of polymorphism which

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would allow us to manipulate collections independently of implementations.

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And here are some of the most commonly used implementations here for the list interface.

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We how our list on linked list in addition to a list link list also implements BQ interface which is

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open to us Dick which is a sub interface off queue for such interface.

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We How has said create or link has it on for cubie how did Dick unlink list for map how hash map tree

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map are linked hash map.

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Note that the class names are quite similar for both set as well as MAP implementations.

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And that's because set implementations internally use map implementations and you can also see that

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there are two interfaces socket set on soldered up on as the names implied then should that the data

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store is automatically socket.

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So as you insert elements into them dig it automatically sorted and are placed at the appropriate positions

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.

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So we will be discussing all of these interfaces and implementations in this chapter along with that

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complexity analysis really for us just because the collection interfaces Un-Dead implementations.

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After that we will discuss Marchman defense and their implementations.

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Finally we were discussing two classes quite recent collections that include genetic algorithms.

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Next song being on searching.

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Note that all of these implementations are Serializable they implement the clone method on most of them

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.

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Also I'm maturing not to use Hollywood.

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Not all the implementations are synchronized which means that none of their methods are synchronized

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.

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That is these methods do not have the synchronized keyword in their declaration so they can be accessed

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by multiple threads at the same time.

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For example if we consider an instance of a then the method of this instance can be accessed by more

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than one thread at the same time.

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So we are talking about a single or oldest object and one method which can be accessed by multiple threads

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at the same time.

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Now if we do not want more than one third to access these methods at the same time then we can still

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provides synchronization and it can be done externally undone.

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We will discuss in multithreading chapter 1.

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Note that there are these three implementations.

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Vector hash table on stack.

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These are legacy implementations which are synchronized.

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The Odeo implementations were not synchronized.

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However it is recommended to not use them any more as synchronization slows things down and it can always

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be added externally instead of vector.

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It is recommended to use an idealist and in place of has table.

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It is recommended to use Hashima and an other deck is recommended to be used in an office doc.

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So that's about it.

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As we saw collections framework includes two distinct inheritance trees on pro-rights highly sophisticated

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data structures that can be used for Dola being powerful applications.

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So let's go ahead and get an in-depth understanding of collections from