Java Collections Framework-Part2 | Interfaces And Classes
Summary
TLDRThis video script offers an in-depth exploration of Java's Collection Framework, emphasizing the foundational Collection interface and its derived interfaces: List, Set, and Queue. It distinguishes between them based on their handling of insertion order and duplicates. The script also introduces the distinct Map interface, which stores data as key-value pairs with unique keys. It briefly mentions utility classes like Collections and outlines various collection classes such as ArrayList, LinkedList, HashSet, and HashMap, setting the stage for实操 demonstrations in upcoming videos.
Takeaways
- 📚 The Java Collection Framework is a set of interfaces and classes that allow for the manipulation and storage of groups of objects.
- 🔑 The root interface in the Collection Framework is the Collection interface, which provides a set of common methods for all collection objects.
- 🧩 The Collection interface is extended by several child interfaces including List, Set, and Queue, each with specific characteristics for different use cases.
- 📝 List interface maintains the order of elements and allows duplicates, suitable for scenarios where insertion order is important.
- 🚫 Set interface does not maintain the order of elements and does not allow duplicates, ideal for unique element storage without order concerns.
- 📬 Queue interface follows the First-In-First-Out (FIFO) principle, used for processing elements in the order they were added.
- 🔄 The Collections class in Java provides utility methods to manipulate any collection, such as sorting, searching, and shuffling.
- 🔗 The Map interface is distinct from the Collection interface and is used for storing data in key-value pairs, with keys being unique.
- 📦 Classes like ArrayList, LinkedList, HashSet, and PriorityQueue implement various collection interfaces, providing different functionalities and performance characteristics.
- 🔍 The choice of collection interface and implementing class depends on the specific requirements of data storage and manipulation, such as order preservation, uniqueness, and access patterns.
Q & A
What is the primary role of the Collection interface in Java's Collection Framework?
-The Collection interface serves as the root interface for all collection-related classes and interfaces in Java. It provides a set of common methods that can be used across various collection objects, such as adding, removing, and checking for the presence of elements within the collection.
How does the Collections class in Java differ from the Collection interface?
-The Collections class is a utility class within the java.util package that contains static methods to operate on or return various collection types, such as sorting a list. It is not an interface but a class that provides additional functionality to manipulate collections, whereas the Collection interface defines the contract for collection types.
What is the significance of the List interface in the Java Collection Framework?
-The List interface is a child of the Collection interface and is used when the order of elements is important. It allows duplicate elements and maintains the insertion order, meaning elements are preserved in the order they were added.
Which Java classes implement the List interface and why would you use them?
-Classes that implement the List interface include ArrayList, LinkedList, Vector, and Stack. You would use these classes when you need to maintain the insertion order of elements and allow duplicates, with each class offering different performance characteristics and capabilities.
What is the Set interface and under what conditions should it be used?
-The Set interface is also a child of the Collection interface and is used when you want to store unique elements without maintaining any order. It does not allow duplicates, and the insertion order is not preserved.
Can you name the classes that implement the Set interface in Java?
-The classes that implement the Set interface in Java are HashSet and LinkedHashSet. These classes are used when you need to ensure that all elements are unique and the order of elements is not a concern.
How does the Queue interface differ from the List and Set interfaces?
-The Queue interface is different from List and Set interfaces as it represents a collection designed for holding elements prior to processing, following a first-in, first-out (FIFO) order. It is typically used for managing tasks in the order they were received.
What is the primary use case for the PriorityQueue class in Java?
-The PriorityQueue class is used when you need to manage a collection of objects where each object has a priority associated with it. It ensures that the highest priority object is always at the front of the queue and is served first.
What is the Map interface and how does it differ from the Collection interface?
-The Map interface is a separate and independent interface in the Java Collection Framework. It stores elements in key-value pairs, where each key is unique but values may not be. It is not a child of the Collection interface and is used when you need to associate values with unique keys.
Which classes in Java implement the Map interface and what are their主要用途?
-The classes that implement the Map interface in Java are HashMap and LinkedHashMap. HashMap is used for fast access to values based on keys, while LinkedHashMap maintains the insertion order of the keys.
Outlines
📚 Introduction to Java Collection Framework
The speaker begins by welcoming the audience and referencing the previous video where the basics of Java collections and the collection framework were introduced. The focus of this session is to delve into the interfaces and classes within the collection framework. The Collection interface is highlighted as the root interface for all collection-related classes and interfaces, providing common methods for collection objects. The concept of a collection as a group of objects represented as a single entity is explained, with examples such as a list of employees. The common operations that can be performed on collections, like adding, removing, and checking for the presence of objects, are discussed. The Collections class from the java.util package is introduced as a utility class containing methods that operate on collection objects, such as sorting an ArrayList.
🔗 Understanding the Collection and Collections Classes
The speaker clarifies the difference between the Collection interface and the Collections class in Java. While Collection is an interface that provides a structure for creating collections, Collections is a utility class that includes methods to manipulate collections, such as sorting. The session continues with an example of sorting an ArrayList using the Collections.sort() method, illustrating practical usage. The speaker emphasizes the importance of understanding the distinction between the Collection interface and the Collections class for effective Java programming.
📋 Exploring List Interface and Its Implementations
The speaker moves on to discuss the List interface, which is a child of the Collection interface. The List interface allows for the insertion of objects while maintaining the order in which they were inserted, and it permits duplicates. Examples of classes that implement the List interface are provided, including ArrayList, LinkedList, Vector, and Stack. The speaker explains that these classes are used when the order of elements and the allowance of duplicates are important considerations for the collection.
🚫 Set Interface and Its Unique Characteristics
The Set interface is introduced as another child of the Collection interface, with a focus on its unique properties. Unlike the List interface, the Set interface does not preserve the insertion order and does not allow duplicates. This makes Sets ideal for scenarios where uniqueness and no specific order are required. The speaker mentions HashSet and LinkedHashSet as classes that implement the Set interface.
📬 Queue Interface for Processing Order
The Queue interface is explained as a child of the Collection interface, designed for handling objects that need to be processed in a specific order, typically a first-in, first-out (FIFO) approach. The speaker uses the example of sending emails to illustrate the concept of 'prior to processing.' The Queue interface is implemented by classes like PriorityQueue, which is highlighted as a key class for managing objects in a queue.
🗂️ Map Interface for Key-Value Pairs
The speaker concludes with an introduction to the Map interface, which is independent of the Collection interface. The Map interface allows for the storage of objects in key-value pairs, where keys must be unique, but values can be duplicated. Examples of classes that implement the Map interface include HashMap and LinkedHashMap. The session wraps up with a summary of the different interfaces and classes discussed, emphasizing their unique characteristics and use cases within the Java collection framework.
Mindmap
Keywords
💡Collection
💡Collection Framework
💡Interface
💡ArrayList
💡LinkedList
💡Set
💡Queue
💡Map
💡HashMap
💡LinkedHashMap
Highlights
Introduction to the Java Collection Framework and its various interfaces and classes.
Explanation of the root Collection interface and its role in the framework.
Description of the common methods available in the Collection interface for all collection objects.
Discussion on the concept of a Collection as a group of objects represented as a single entity.
Introduction to the Collections class in the java.util package and its utility methods.
Example of using the Collections.sort method to sort elements in an ArrayList.
Differentiation between the Collection interface and the Collections class.
Overview of the List interface as a child of the Collection interface.
Characteristics of the List interface: preservation of insertion order and allowance of duplicates.
Introduction to the Set interface as another child of the Collection interface.
Characteristics of the Set interface: no preservation of insertion order and no allowance of duplicates.
Introduction to the Queue interface and its use for representing objects that are prioritized for processing.
Explanation of the First-In-First-Out (FIFO) concept in Queues.
Introduction to the Map interface and its use for storing objects in key-value pairs.
Characteristics of the Map interface: uniqueness of keys and allowance of duplicate values.
Overview of the different classes implementing the List, Set, and Queue interfaces.
Introduction to the classes implementing the Map interface, such as HashMap and LinkedHashMap.
Summary of the Collection Framework's interfaces and their respective use cases.
Announcement of future videos demonstrating practical usage of the Collection Framework's interfaces and classes.
Transcripts
hi everyone welcome you all in our previous video we have seen what is collection and what is the
collection framework and what are the differences between collection and collection framework
now i have told you like collection framework is basically contains n number of interfaces and
classes right so first of all let us see what are the different interfaces and classes are available
and then we will see each and every class in interface in detail so in the today session the
mainly focusing on what are the main interfaces and what are other derived classes are available
in the collection framework so the first and most important collection framework
in the main interface in the collection framework is collection
interface so the name of the interface is collection so basically this is an interface
so this collection is a root interface we can simply call as a root interface for all other
collection related classes and interfaces and which contains a common methods which we can use
for other collection objects so for example we have understood what is collection rights what
is a collection means a group of elements we can represent a group of elements as a single entity
so for example i have an organization in employees let's say i have emp one object
mp2 object i have emp3 object and so on so there are multiple objects i have i'll representing all
objects as a single entity so this is a single entity this is basically we can do by using a
collection so collection is nothing but a group of objects together we can call as a group of object
is a collection so to representing this collection we need certain interfaces and classes right
so if i just look at here we have multiple objects representing with single entity here right so
what are the common operations we'll do on these objects normally when i have some collection here
we add some object into this collection or we want to remove this collection from this remove
this object from the collection and sometimes we can check whether the object is present inside
the collection or not so these are the common operations we can do on the collection so to do
these operations like these operations are common for all kinds of collections so adding a new
object or removing an object or we can verify the existing object which whether is available inside
the collection or not so all these things we can do by using certain methods so those methods
are commonly have across all the collection classes so those methods are present inside the
collection interface so the collection interface is used to representing group of objects as a
single entity and which contains a common methods which are required for other collections so most
of the times the methods which are defined inside the collection interface are common across all the
collection classes so this is the first and most important collection we have as part of collection
framework so this is a collection interface now in java we have something called collections
so what is collections so this is i'm talking about collection this is purely an interface
now apart from this we also have one more thing called collections so what about this collections
so collection is a group of elements we can represent multiple objects as a single entity
which is a collection and the collection if you want to create we can use a collection interface
so we'll get all the method from this but what is about what about the collections so collections in
java which is actually a class from java dot utils package so in java we have a java.utils package
so the collection is a class which is present inside the java.utils class utils package so what
basically correction class contains collections class also contains certain methods and these
methods we can use for collection objects so the collections is a pre-different class which is
available inside the java.util package in java so we can use this collections class contains certain
number of methods and those methods we can use to perform certain operations on collection objects
now let me show you one example here so to understand this and let's take a small arraylist
object so let me just create one arraylist let us say ar i have an error list and i want to i have
some elements in the arraylist so element1 and 2 and element 3 are these are different objects
so i want to sort all these objects or i want to sort all these elements inside the array list
so error list is a basically a collection object now to sort all these elements what you can do is
we can use a collections class so we have a class called as a collections from java.util package
inside this collection we have a method called sort and we can pass this array list here and
then what happens the collections inside this class we have a sort method which is a utility
method we have and that particular method will sort the elements inside the error list so what
we have to understood here is the collections is a a predefined class which is available inside the
java.util package and which is providing certain number of methods and those methods we can use
to perform certain operations on the collection objects so here the collection is an interface
collections is a a predefined class which is available inside the collections.java.util package
okay so like this like a sort method we have a n number of methods are available
in the collections class and we can use those methods to perform certain operations on the
collection object so this is a basic difference between collection and collections now collection
and the collections let me just repeat once again so collection is
an interface which is comes under collection framework and collections is a predefined class
which contains some utility methods by which we can perform certain operations on the collection
objects so that is the difference between collection interface and collection collection
collections this is a class okay so collection is an interface collections is a class and which
contains the methods and these methods we can use for collection objects to perform
certain operations so this is a very very important thing so collection is a first and
root interface which contains the methods which we can use commonly across collection classes
now this is the first interface from this interface we have different type of interfaces
created and again those interfaces are implemented by different number of classes
now let us see what are other interfaces we have as part of collection framework and what are other
classes are available which are implemented those existing interfaces in the collection framework so
now we discussed the collection interface so the collection interface is a base interface we have
in the collection framework so this particular collection interface this is a basically interface
which is having a child interfaces so the main interface here is list is one interface and
we have also set interface set is also one more interface list interface set interface
and we also have queue interface so these are the main three interfaces which have
created as part of child of collection interface so list is interface of the child of collection
interface set is another interface which is also child of collection interface
and q is another interface which is also shield of the collection interface again each and every
interface is uh implemented by using different classes so we will discuss those classes later
so let us first focus on what are the main interfaces we have in the collection framework
now let us see one by one so collection is a main interface is a parent interface and this interface
again implemented there are chain interfaces list to set and queue interfaces so these three
interfaces are jail interfaces of collection so now we will discuss what exactly list
set and queue interfaces and what are other classes which are available for
implementing these interfaces so first let us start with the list interface okay
so first let us start with the list interface okay so list so list is a interface which is
a child interface of the collection interface so root interfaces collection right it's a collection
and list is a shared interface of the collection so list is a child interface of the collection
now what is exactly list me so this is also an interface so the first point is the list
is a child interface of the collection interface and whatever methods we have in the collection
the same methods are also available in the list interface and the second point is list is a chain
class of child interface of collection interface the second first point list is child of collection
collection interfaces the first point the second point is when we have to use a list
interface so this particular list interface we can use suppose i have a group of objects let
us say i have a group of objects i want to store all of them as a one entity so that is basically
called as a collection right so i want i have a group of objects i want to store all of them
as a single entity now my requirement is i want to store all these elements in the sorted order
okay i want to store all the elements in the sorted order so for example let us say
here if i take group of elements in whichever order we have inserted all the elements into this
element in the collection in the same order it should preserve so for example let us say
i have taken one collection let us say this is my collection
and i am going to insert multiple objects into this collection
so whenever i add a new object the insertion in whichever order i have inserted all the objects in
the same order it should insert so that means the insertion order should be preserved okay so when i
add a new insert a new element that should be here so this particular collection should maintain the
uh inserted insertion order should be preserved so in whichever order we have
inserted these elements or objects in the same order it should present so that's a
important thing so here in that particular case we use list interface so if you want to add a group
of objects then suppose the insertion order should be preserved and at the same time duplicates also
duplicates also allowed there is another point the first point should be insertion order should be
preserved at the same time duplicates also should allow in those two cases we go for list concept
so here insertion order preserved so this is the first thing and the second thing is duplicates
duplicates a lot so in these two cases we will prefer to use list concept so what is list means
a list is a a collection which we can store a group of elements or objects but in that case
when we have to go for list if you want to add all the group if you want to maintain all the
group of elements in the collection and where the insertion order should be present insertion order
should be preserved so which in whichever way we have inserted all the elements or objects in the
same order it should maintain the second point is duplicates also allowed here so if you want
to insert another element same object again it should allow us so in these two cases we go for
list concept so this is one of the collection we have and the list is a jail interface of
collection interface now so what are the classes are available which are implemented this list
interface so now we'll discuss about those classes so list interface is implemented by using a
different classes let me just rub this so list is an interface right interface alone we cannot
directly access so we have a certain number of classes or implemented this list interface so what
are the different classes have implemented this interfaces the first class is a released class
a released is a class which is implemented all the methods which are available in the
list interface and the next one is linked list arraylist linked list so this is another class
which is implemented this list the first one is arraylist is a class linked list is another class
and we also have something called vector so this is also another kind of a collection and
again this is implemented this is extended from the stack so these are all different classes which
are implemented this list interface and list is a child interface of collection and j list interface
is implemented by using different classes so error list is one class linked list is another class
vector and stack so these are also classes and these are called as a legacy classes from the
old versions of java you can find them so we can call them our vector and stack is a legacy classes
so legacy classes so these are the classes are available which are implemented
based on the list interface and list interface is a jail interface of the
collection so so far we have seen two interfaces in the aspect of collection framework so one is
collection interface there is a parent interface for all other collections
inside the collection interface we have a common methods which are required which are
useful for all other collection objects and the second interface is a list interface and
which is derived from the collection interface so this is the channel interface of collection
and when we need to go for list suppose if you want to store a group of elements and
those elements when i add a new elements or when i insert a new elements the insertion order should
be preserved and the second thing is duplicates also should be allowed in those two cases
we will go with the list interface concept and the list is implemented by using arraylist class
linkedin list class and vector and stack classes so these are the set of classes are available
which are implemented list interface now apart from this list interface there are some other
channel interfaces also there for collection interface now we will discuss so we have seen
what is the list interface and when we need to go for list interface now i will talk about other
type of collection that is set interface so set interface is also derived from the
collection so set is also an interface set is also an interface and this is again chilled interface
of the correction interface list set is also channel interface of the collection interface
now so when we need to use set interface so when you go for a list interface are two options one is
the insertion order should be preserved the second point is duplicates also should be
allowed in those cases we have preferred the list now here in the set interface the first
thing is insertion order not present insertion order not present insertion order not preserved
okay so in whichever way we have inserted those elements it will not maintain the
same order inside the collection so insertion order not preserved and the second point is
duplicates duplicates not allowed duplicates not allowed so in that list the duplicates should be
allowed but in the set duplicates are not allowed so when we need to go for set interface the first
thing is insertion order is not preserved and duplicates are not allowed if i add one object we
cannot add the similar object again and again so the duplicates are not allowed in these two cases
we go with the set interface and this is also a child interface of collection interface now
what are the other classes which are implemented based on the set interface
so now let us see what are those classes so the set interface is implemented by using a class
called hash set so this is one class we have and the same interface is implemented by using
another class called linked has a shirt linked hash set linked let me write once again so here
linked hash so this is another class we have so these are the two classes have implemented
set interface set interface so when we need to go for set interface set interface you
can be used whenever the insertion order not preserved we don't want to preserve any insertion
order then we can go for the set and duplicates also not allowed so in the set duplicates also
not allowed in these two criterias we can go and prefer to use set interface so this is
one more interface we have which is part of the collection interface so far we have discussed two
main interfaces which are chilled interfaces of collection interface so what are those
interfaces the first one we have discussed about a list interface the second one we have discussed
about set interface and these two interfaces are derived from the collection interface itself now
what are the differences we have observed the list inside in the list in case of list insertion order
insertion order should be preserved but in case of set it is not preserved in case of list
duplicates are allowed or not duplicates allowed but in case of set duplicates are
not allowed so these are the two differences between the list and the set collections which
are derived from the same interface which is a collection now apart from this list
and set there is one more interface which is also derived from the collection interface
now we will see that collection so the next interface is apart from this
a list and set we also have one more called q q is also an interface so q is also an interface
and which is also implemented which is also extended from the collection interface so this
is a parent and this is a child interface just like a set and list queue is also another child
of the collection interface now when we need to go for the queue so when we need to prefer the queue
so q is we can use a cube whenever you want to representing a group of objects
which are prior to processing which are prior to processing so what is meant by prior to processing
suppose i maintain different objects as a group and these objects should be prior to processing
so then we can go for the queue so what is prior to processing means
so let us try to understand it is basically first in first out concept so here i have different
list of emails okay i have different list of emails let's say i have a thousand emails
okay i have a thousand emails total 1000 emails list i have right so 1000 emails list i have i
want to send an email i want to send an email to all these people and the list of recipients
okay so when i compose when i send this email and put all these email address in my cc list okay so
then what happens is this email will not go to everyone at the same time so first it will send
to the first guy and second third fourth and fine right so there will be a queue will be maintained
and uh the emails will be sent to image same email will be sent to multiple people one after another
so this is a basically called as a uh this is basically called as a prior to processing so
here there is a list of email ids we have so these are prior to processing so here basically first in
first out concept so whichever first is in and this that will be first out so first in
and first out so the queue is an interface we can use whenever you have a objects which are prior to
processing which are prior to processing so then we will prefer queue concept so this is also one
of the interface uh child interface of collection interface now what are the different classes are
available which are implemented this q interface so q interface is implemented one class called
priority queue so there are another classes also there but here i'm just writing the main classes
which we are going to use very frequently so here priority queue is there so this is the class which
is implemented this particular interface okay q interface so these are the uh few interfaces
we have in the collection framework all the interfaces are jailed interfaces of collection
interface now let me just summarize what are the interfaces we have discussed so far which
are comes under collection interface the first interface we have discussed is list interface
the second interface we have discussed is set interface the third one we have discussed is
queue interface and the list interface will be preferred if you have a group of objects
where insertion order preserved and duplicates are allowed then we can go for list interface
list collection and suppose i have a group of elements or group of objects where insertion order
not preserved duplicates also not allowed then we can go for set interface and suppose i have a
group of elements which are prior to processing then we can go for queue interface and again
each interface is implemented by using different classes okay so these are all basic interfaces we
have under collection interface now apart from this apart from these all interfaces there is
another interface we have called map interface that is a completely independent interface of
collection that is nowhere related to collection collection interface is one side let us say here
we have seen collection interface this so again in the collection interface we have seen a list set
and the queue so these are the interfaces we have seen apart from this there is one more independent
interface we have called as a map so this is a different kind of interface
and this is not a child interface of the collection interface so map is a not jail
interface of the collection interface now what map is contains what are the different interfaces and
classes we have let us see so when we need to go for the map so map is another interface we
have so when we need to go for the map so map is also by using map also we can represent a group of
elements or group of objects but those objects will be in the form of key and a value pair
so for example i have a data something like this right say i have uh employees let's say emp id 101
i have a david and one zero two i have a smith and one zero three i have a squat so i have a multiple
ids and i have a multiple names and if i just look at here this kind of data so here every
element every element is an object so here these are all objects and the names are also object
in the map we can call them as a keys and these are all the values so key and value pair means
this combination is called as a key and a value pair so if you want to store this kind of data we
will go for map interface so in the map interface we can representing group of objects or elements
in the form of key and value pair and every key is an object and every value is an object
but here the rule is the keys cannot be duplicated so for example when i say one zero one i already
inserted i cannot add one more one zero one so the duplicates are not allowed in case of keys
but the values can be duplicated so if i add david here the david can be repeated once again so
in the map the data will be maintained in the form of key and value pairs and
each key is an object each value is an object and keys are unique so keys
we cannot duplicate duplicates are not allowed as a keys but values can be duplicated so this is a
this is a way we can use map interface so map interface will be preferred if you want to store
the objects in the form of key and the value pair and what are other classes are available
which have implemented this map interface now we will discuss them so map interface is also
implemented by using different classes so the map interface is implemented so map interface is
implemented by using hash map so this is a class and which is also implemented by using
linked hash map okay so linked hash map linked so these are the two classes which you have
implemented this map interface okay so map is a completely different interface which is
also comes under collection framework but this is nowhere related to collection so collection is a
parent class and a map is a different class okay so this is how we need to understand all
the interfaces and the classes from the collection framework so from the next video i will show you
how we can work with the different interfaces and different classes all right so that's all
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