Java Collections Framework-Part1 | Collection Vs Collection Framework

Summary

In this HDT Channel tutorial, Pawan introduces Java's Collections Framework, explaining the concept of a 'collection' as a group of objects. He differentiates between a collection and the framework, which provides classes and interfaces to manage collections. Pawan highlights the limitations of arrays, such as fixed size and the inability to store heterogeneous data, and contrasts them with the flexibility and features of collections like ArrayList and HashMap. The session sets the stage for upcoming in-depth discussions on various collection types and their practical applications in Java.

Takeaways

• 😀 A collection is a general term for a group of objects, like multiple students in a class or employees in an organization.
• 📚 The Java Collections Framework provides a set of interfaces and classes that allow objects to be stored and managed in various ways.
• 🔑 The main difference between a collection and the Collections Framework is that the former is a general term, while the latter is a set of tools in Java for managing collections.
• 🚫 Arrays in Java have limitations such as fixed size and the inability to store heterogeneous data types.
• 🛠 The Collections Framework overcomes the limitations of arrays by offering growable, flexible data structures that can store various data types.
• 🌐 The framework includes classes and interfaces like ArrayList, HashMap, TreeMap, Stack, and LinkedList, each with its own specific use cases.
• 💡 The Collections Framework is beneficial because it provides ready-made methods for common operations, such as sorting and searching, without the need for custom logic.
• 📈 The flexibility of the Collections Framework allows for dynamic resizing, which is not possible with fixed-size arrays.
• 🔄 It supports both homogeneous (same data type) and heterogeneous (different data types) data storage, making it more versatile than arrays.
• 🔑 The framework uses underlying data structures to implement its classes and interfaces, which is why it can offer a rich set of methods for manipulating collections.

Q & A

What is the basic definition of a 'collection' as mentioned in the script?

A 'collection' is a general term used to represent a group of objects as a single entity. For example, multiple students in a class can be referred to as a collection of students.

What is the Java Collections Framework and how does it differ from a simple collection?

The Java Collections Framework is a set of interfaces and classes that allow objects to be stored and managed in various ways. It differs from a simple collection by providing a structured way to handle groups of objects with methods for operations like sorting and searching.

Why do we need the Java Collections Framework according to the script?

We need the Java Collections Framework to overcome the limitations of arrays, such as fixed size, inability to store heterogeneous data, and lack of ready-made methods for operations like sorting and searching.

What are the limitations of arrays as discussed in the script?

Arrays have limitations such as being of fixed size, not being growable at runtime, and only allowing the storage of homogeneous data types.

How does the script illustrate the concept of storing multiple elements using an array?

The script illustrates storing multiple elements using an array by creating an array of integers where each index represents a memory location that can hold a value, allowing multiple values to be stored in a single variable.

What is the difference between homogeneous and heterogeneous data as explained in the script?

Homogeneous data refers to an array or collection that can only store elements of the same data type, whereas heterogeneous data means a collection can store elements of different data types.

How does the script explain the concept of an 'object array' in Java?

An 'object array' in Java is an array that can hold objects of any type, allowing for the storage of both homogeneous and heterogeneous data. This is in contrast to a primitive type array, which can only hold values of a specific primitive type.

What are the advantages of using the Java Collections Framework over arrays as mentioned in the script?

The Java Collections Framework offers advantages such as dynamic sizing, the ability to store both homogeneous and heterogeneous data, and the availability of ready-made methods for common operations like sorting and searching.

What are some of the classes and interfaces available in the Java Collections Framework as hinted in the script?

Some of the classes and interfaces available in the Java Collections Framework include ArrayList, List, HashMap, Hashtable, TreeMap, Stack, and LinkedList.

How does the script suggest overcoming the limitations of arrays?

The script suggests overcoming the limitations of arrays by using the Java Collections Framework, which provides classes and interfaces that allow for dynamic sizing, storage of mixed data types, and built-in methods for various operations.

Outlines

00:00

📚 Introduction to Java Collections

The speaker, Pawan from HDT Channel, introduces the topic of Java Collections Framework. He explains the basic concept of a 'collection' as a group of objects, using examples such as students in a class or employees in an organization. The session aims to clarify the difference between a collection, which is a group of objects, and the collection framework, which is a set of classes and interfaces in Java that allow these groups of objects to be represented as single entities. The speaker emphasizes the need for the collection framework to efficiently manage groups of objects in Java programs.

05:05

🔑 Understanding Java's Collection Framework

Pawan further elaborates on the Java Collections Framework, contrasting it with the limitations of arrays. He points out that arrays can only hold a fixed number of elements and are limited to storing homogeneous data types. To overcome these limitations, the collection framework provides various classes and interfaces like ArrayList, HashMap, and others. The framework allows for dynamic sizing and the storage of both homogeneous and heterogeneous data types. The speaker also touches upon the lack of built-in methods in arrays for operations like sorting or searching, which are available in the collection framework.

10:09

🚫 Limitations of Arrays in Java

This section discusses the specific limitations of arrays in Java, such as their fixed size, which means they cannot grow or shrink at runtime. This inflexibility can lead to wasted memory if the array size is overestimated or an 'IndexOutOfBoundsException' if more elements are added than the array can hold. Additionally, arrays can only store homogeneous data, restricting the types of elements they can contain. The speaker also mentions that arrays do not utilize underlying data structure concepts, which means there are no ready-made methods for common operations, requiring custom logic for tasks like sorting or searching.

15:10

🌟 Advantages of Collections Over Arrays

Pawan highlights the advantages of using collections over arrays. Collections are growable, allowing for dynamic addition and removal of elements without the risk of memory wastage. They can store both homogeneous and heterogeneous data, providing more flexibility in data storage. Furthermore, collections are implemented with underlying data structures that provide ready-made methods for operations like sorting and searching, eliminating the need for custom programming logic. The speaker sets the stage for upcoming sessions that will delve deeper into the different types of collections available in Java.

20:11

🔍 Overview of Java Collections Framework

In the concluding part, Pawan summarizes the introduction to Java Collections, emphasizing the need for the collection framework due to the limitations of arrays. He outlines the benefits of the framework, such as its growable nature, ability to handle diverse data types, and the presence of built-in methods for common operations. The speaker also hints at future sessions that will explore various collection types, classes, and interfaces in detail, providing a comprehensive understanding of how to work with Java Collections.

Keywords

💡Collection

In the context of the video, a 'Collection' refers to a group of objects treated as a single entity. This is a fundamental concept in Java programming, where collections are used to manage and organize data. The video explains that a collection can be a group of students, employees, or any other objects, and it is used to represent multiple objects in a unified manner. For instance, the script mentions 'collection of students' and 'collection of employees' to illustrate this concept.

💡Collection Framework

The 'Collection Framework' in Java is a set of interfaces and classes that allow for the manipulation and storage of groups of objects. The video emphasizes that this framework is essential for representing a group of objects as a single entity in Java. It provides various classes and interfaces such as ArrayList, HashMap, and others that facilitate the creation and management of collections. The script contrasts the Collection Framework with the basic concept of a collection, highlighting the framework's role in providing the necessary tools to work with collections in Java.

💡ArrayList

An 'ArrayList' is a specific type of collection in Java that can dynamically resize and hold a variable number of objects. The video script uses ArrayList as an example to demonstrate how a group of elements can be stored in a single entity. It shows how to create an ArrayList and add elements to it, which contrasts with the fixed size of arrays and highlights the flexibility of the Collection Framework.

💡Homogeneous Data

The term 'Homogeneous Data' is used in the video to describe a collection that contains elements of the same data type. The script explains that arrays in Java can only store homogeneous data, meaning all elements in an array must be of the same type. This is a limitation of arrays, as opposed to the Collection Framework, which can handle both homogeneous and heterogeneous data.

💡Heterogeneous Data

Contrasting with 'Homogeneous Data,' 'Heterogeneous Data' refers to a collection that can contain elements of different data types. The video script points out that while arrays are limited to homogeneous data, the Collection Framework, particularly object arrays, can store heterogeneous data, allowing for more flexibility in how data is managed in Java programs.

💡Fixed Size

The 'Fixed Size' concept in the video refers to the limitation of arrays in Java, where the size is determined at the time of creation and cannot be changed. The script uses this term to highlight the inflexibility of arrays compared to the dynamic nature of collections in the Collection Framework, which can grow or shrink as needed.

💡Growable

The term 'Growable' is used to describe the ability of collections in the Collection Framework to dynamically resize as elements are added or removed. The video contrasts this with the 'Fixed Size' nature of arrays, emphasizing the advantages of using collections for managing data that may change in size during the execution of a program.

💡Underlying Data Structure

An 'Underlying Data Structure' refers to the fundamental structure that a collection or data type is built upon. The video script explains that arrays in Java do not utilize an underlying data structure, which means they lack ready-made methods for operations like sorting or searching. In contrast, collections in the Collection Framework are implemented using various data structures, providing built-in methods for common tasks.

💡Ready-Made Methods

In the context of the video, 'Ready-Made Methods' are pre-defined methods available for performing operations on collections, such as sorting or searching. The script contrasts the lack of these methods in arrays with the availability of such methods in collections, which are implemented using underlying data structures. This allows for easier manipulation of data without the need to write custom logic for basic operations.

💡Object Array

An 'Object Array' is a type of array in Java that can hold objects of any type, thus allowing for the storage of both homogeneous and heterogeneous data. The video script uses object arrays as an example to show how the limitations of storing only homogeneous data in regular arrays can be overcome, although it still maintains the fixed size limitation of arrays.

Highlights

Introduction to Java Collections Framework

Definition of a Collection as a group of objects

Explanation of Collection Framework comprising classes and interfaces

Differentiation between Collection and Collection Framework

Example of representing multiple students as a Collection

Use of ArrayList to represent a Collection of elements

Rationale behind needing a Collection Framework in Java

Demonstration of variable declaration and value assignment in Java

Limitations of Arrays in Java such as fixed size and homogeneous data storage

Concept of Object Array to overcome limitations of Arrays

Advantages of Collection over Arrays in terms of size flexibility

Ability of Collections to store both homogeneous and heterogeneous data

Availability of ready-made methods in Collections due to underlying data structures

Comparison between Arrays and Collections highlighting their differences

Introduction to various Collection types like ArrayList, HashMap, and more

Overview of upcoming sessions covering detailed exploration of Collection types

Transcripts

hello everyone welcome you all this is pawan from  hdt channel so from today onwards we are going to  

see java collections framework so as part of  today's session we'll see some detection part  

like what is collection and what is collection  framework and what are the different collection  

types are available in java right so first  of all let us start with what is collection  

so what is a collection so first let us try  to understand this term what is collection  

so this is basic general term which you can use  commonly like group of objects is a collection so  

for example let us say i have multiple students  in the class it's a student 1 and student 2  

and student 3 so all together we  can call as a collection of students  

and similarly when i take an organization we  have a multiple employees let's say employee one  

employee two and employee three and so on so all  of them comes under one collection so collection  

of employees similarly collection of pins  or collection of animals so we can use this  

collection term in general so that representing a  group of objects so that is simple definition what  

is meant by collection so collection is a group  of objects and the collection is representing  

it is a single entity which is representing  multiple objects collection is a single entity  

which is representing multiple objects but  what about the collection framework so in java  

uh to represent group of objects into a single  entity we need certain number of classes and  

interfaces so collection framework which will  provide you those classes and interfaces so what  

is collection framework means it defines  the different interfaces and classes by  

which we can represent group of objects into a  collection so that is a basic difference between  

collection and collection framework so let  me just repeat once again with some examples

so what is a collection and collection  framework so for example let us say  

a collection so i have a student one and i  have another student two and i have another  

student three so i have a three students so  collectively i will call as a one collection  

collectively i have called as a one collection  so to representing this collection or to  

representing a group of element we need a  collection so how we can represent a group  

of element into single entity we need a special  classes or interface so for example in java  

so we have something called arraylist so when  i say arraylist equal to new arraylist when i  

create an object like this i can store a group  of elements into error list so this is a one  

example of the collection framework so the  collection framework is a group of classes  

and interfaces by which we can represent a group  of objects into single entity so that is the basic  

difference between collection and collection  framework so before discussing the collection  

framework first of all we need to know why we need  to go for collection framework why we need to have  

a collection framework in java so to understand  this better let us see one example suppose in java  

so if you want to uh store a value into a variable  so first we will define like this so first we will  

have some data type and then we define some  variable name let's say a and here i'll say  

something called 10 so what exactly this is  representing int is a data type and a is a  

variable 10 is a value and similarly if i want to  store one more value into a variable so again i  

have to define one more variable and then i can  store some other value similarly if you want to  

store 100 numbers like this so 100 variables we  have to create so to store 100 variables we have  

to create to store 100 values we need to create  100 variables so this is a not a best programming  

practice so it is not a best programming  practice so what we have to do is  

to representing many numbers so here let us  conserve this each and every value is one object  

to representing these all the values we will  create a one variable let us say i will create  

one small variable by using array so when x  for example let us say integer a and equal to  

new int and here i'll say 100 so when i  create an array variable like this in java  

so there is a single variable which can hold  multiple values that means it can hold group of  

elements or group of objects so here every element  so for example if i create 100 like this which  

will create 100 memory locations like this let us  say here starting from 0 index is starting from 0  

1 2 3 so 100 locations it will be created so in  each and every location we can put some value or  

sometimes we can also store object elements so  we can use this array which will representing  

or which can store multiple elements or  multiple objects so is it it is clear till here  

because the collection is nothing but  to representing the group of elements  

as a single entity which is a collection  so if i just look at this example  

so we can achieve this somehow by using array  concept because here if i if i specify the size  

here so you can store some group of elements into  a single variable so if you if you have some value  

here 10 if you want to access this value so we  can say a of zero so by using this index number  

i can access the values from this array  so if you just look at this example  

in array concept we have certain limitations so  what are those limitations we have in this area  

so now we will discuss this because to overcome  those limitations corrections framework framework  

come into picture so what are the problems  with the arrays concept so let us see here  

i created one array let's say int a and equal to  new end of here i can say some size let us say  

i put some 10 so when i say 10 here  which will create 10 different locations  

and array will be created like this and 10  rows will be created index will start from 0  

so 0 1 2 and the last index will be 9 because  the index will start from 0 so the last index  

will be n minus 1 always so it is 9 here so we can  store different elements here 10 or 20 30 40 and  

so on so this is normal array concept so in this  array concept what is the problem with this is  

when i create an array like this in the array  we can store homogeneous data only so what is  

homogeneous data means we can store only same  group of elements so same kind of elements  

so that means if array is defined with the integer  type i can store only numbers in that suppose if  

i create this array with double or string type  i can store only string on that so that means  

array will allow us to store only homogeneous  data so homogeneous data in the sense the same  

kind of data similarly if i create a array with  a student class object let us say here student  

stu and equal to new student of i'll say 10  now observe this instead of data type i use  

some class here student so when i create  array like this student sto is an array  

and new student of 10 so in this particular  array so which will create 10 locations  

right which will create a 10 location let's say 0  1 2 and so on so in every location we can we can  

store some student object details like here one  object we can store and here one object another  

object we can store or here we can store another  object so again here if you just look at here  

when i create an array with the student type i can  store only student information in those locations  

it can hold only student objects but here when  i create a student stu and here i'll say new  

i'll say customer so this is a different class so  this cannot hold now because the array can hold  

only homogeneous data so homogeneous data means  the all the data elements should be the same type  

so we cannot store multiple data elements in the  array so this is a one limitation we have this in  

array but still we can overcome this limitation  by creating object array so instead of creating  

the into or instead of for specifying the student  specifically if i create an object array which can  

hold everything so for example let me create an  object let me create array with the object type  

so this is called object array so now  a is created let's say new [Music]  

so let me just say like this this is an object  array so new object now observe this so here i'll  

say 5 so now i created an object array so when  i create an object array i can store homogeneous  

data as well as heterogeneous data that means it  can hold same data type elements and i can also  

store multiple data type of elements so for  example so it will create multiple locations  

five locations and here i can put number or here  i can put decimal number or you can here i can  

put a string and so on similarly a different  type of objects also we can store in this array  

so somehow we can achieve this we can overcome  this problem by using object array so here also  

we are representing group of objects into a single  entity so group of objects into a single entity  

so this is also a kind of a collection now we'll  see the what is the problem with this array so  

based on this problem we can overcome this  problem by using collections concept so when  

i take this array concept so the first problem  with this is the first problem with the array is  

the array is having a limited size so for example  when i say 5 that value is a fixed so i cannot  

store more than 5 values so array is fixed in  size so at the runtime i cannot increase or  

decrease the size so five is a fixed size so when  i define the array that the size is fixed so it  

will create five elements so it can create five  store five memory locations and i can store only  

five elements into this array and if you are  trying to store one more element it will throw  

an exception like error index out of one exception  so that is a problem suppose if i created five  

elements in the array five memory locations i  created and if i store only three elements when  

i store only three elements and rest of the spaces  will be wasted so this is a one problem with the  

array so array size is always fixed so at the  runtime we cannot increase or decrease the size  

and suppose if we want to store more than these  elements still there is a problem and if i store  

less number of elements still the memory will be  wasted so this is the one problem with the array  

and the second problem is the second problem is  so what does that mean is array is a fixed in size  

means it is not growable so these are technical  terms like arrays are not growable in nature  

so that means at the run time we cannot  increase or we cannot decrease the  

size of an array so that is that means array is  a not growable in nature it is not growable in  

nature this is a first problem so the second  problem with the array is size is fixed and  

second problem is we can store only same data  type of element that means homogeneous data  

okay only homogeneous data we can store in  this area only homogeneous data that means  

same data type of elements we can store  in this array there's a second problem  

and we already seen sizes fixed because at the  runtime we cannot increase and we cannot decrease  

the size and they are not growable in nature so  these are the two problems the third problem is  

so while implementing the arrays they have not  basically used any data structure underlying  

data structure concept so while implementing the  arrays in java they are not basically using an  

underlying data structure concept so we cannot  it cannot support any ready-made methods we  

can say ready-made methods what is ready-made  methods means suppose when i create an array  

right if i want to sort some elements or if  you want to set some element is there in the  

array or not i need to write a logic for that  i don't have any predefined methods for that  

okay so because the arrays have implemented no  arrays are not implemented by using any underlying  

data structure so that is a problem so the reading  ready-made methods are not there in the arrays  

so this is one more problem so arrays are  in fixed in size and error arrays hold only  

homogeneous data and arrays are not implemented  by using any data underlying data structure  

so we don't have ready-made methods we cannot use  those methods and if you want to do any operations  

on the arrays we have to write a programming logic  so this is a these are the basic problems with the  

normal arrays concept so to overcome these  problems to overcome these problems we have  

collections available in java so collections  framework so now we will discuss why we need a  

collection so in the normal arrays concept we have  these problems so we have in fixed size we can  

store only homogeneous data and they don't have  any underlying data structure so we cannot use any  

ready-made methods so when you come to the  collection framework so collection framework  

so java in the collection framework they have  provided certain number of classes interfaces  

so we have something called arraylist  and we have something called list is  

also an interface which is realistic derived  from the list and we have something called  

hash map and we have something called okay so  hash table and we have something called tree  

stack and so on so there are so many classes and  interfaces are available so by using all these  

types right we can maintain the we can store a  group of elements into a single entity so what are  

the additional advantages we will get when you use  the collection types over arrays concept so far we  

have seen arrays concept how we can store multiple  data type of elements and also we have seen what  

are the limitations we have in this array right  so now i will show you how we can overcome those  

problems by using this collection types so let  us try to compare arrays and collection so why we  

need to go for arrays because in arrays we have  some limitations to overcome those limitations  

we go for collection concept so well  let us compare with erase and collection  

array and collections so collection in the sense  it can be any collection like it can be array  

list hash map vector tree whatever linker list  everything all that comes under the collections  

now what are the basic differences between  collections and errors concept so we have  

noticed we have some limitations in array so  what what is the first limitation is a fixed size  

so if you want to create an array before that  we need to know how many elements we are going  

to store in this array and then we can create an  array we can proceed further so the size is fixed  

at the runtime if you want to add a new values  or if you want to remove the existing values  

it is not possible in this areas concept okay so  we have to write a programming logic so fixed size  

so the runtime we cannot increase or decrease  the size and if you want to store more than more  

elements than the size it will throw an exception  similarly if you want to store a less number of  

elements based on the size suppose if i say size  is 10 if i store only 5 elements still the rest of  

the memory will be wasted so basically areas are  not growable in nature but whereas in collection  

they are growable in nature growable in  nature so what does it mean is at the runtime  

if you want to add a new elements we can still  keep on adding a new data elements and similarly  

if you want to reduce the elements if you want to  remove the elements at the random we can remove  

the element so because of the removing there is  no memory wasted will be there so collections  

are growable in nature whereas arrays are  not growable so that is fixed size there is  

a first difference and now come to the second  difference is arrays can hold homogeneous data  

it is can hold homogeneous homogeneous  data when you come to the collections  

it can hold homogeneous data homogeneous data  plus heterogeneous data heterogeneous in the data  

means it is can have all kinds of data elements  so different data type of elements can store  

so that is an one more advantage of collection  framework so homogeneous data plus heterogeneous  

data also can be stored in the collection so  there's a second one so third difference is  

in the normal arrays concept so because arrays  are not implemented based on by using any data  

structure underlying data structure so ready-made  methods are not there so if i create an array if  

you want to search an element if you want to sort  an elements we have to write a programming logic  

okay so that means there is no underlying  structure so there is no underlaying

underlying data structures so there is no  ready-made methods available so ready-made methods  

not available if you want to do any operations on  java we have to write a programming logic for that  

but when you come to the collections  the collections are implemented  

by using some data structure underlying  data structure so so it is implemented  

by using data structure underlying data structure  so that means the ready-made methods are available  

so ready-made methods are available so what  is ready-made methods means for example  

if i create a normal array right so if you want to  sort or if you want to search in elements in this  

array we have to write a programming logic for  that so instead of a when i create an error list  

right so when i create an error list basically  what is an error list real list is a collection  

so when i create an error list so we don't need  to write a such logic for that so we have a ready  

methods or this or sort or search so we have  a ready-made methods are there so by using  

those ready-made methods we can do different  operations on the collection so that means so  

there is no underlying data structure for the  arrays concept whereas in the collection all  

types of collections are implemented by using some  underlying data structures so that's the reason  

the ready-made methods are available so for every  collection there are certain methods are available  

by using those methods we can perform certain  operations on the collections so this is  

the way we need to understand what exactly  collection means and collection framework and  

what are the different classes and interfaces  are available in the collection framework  

right so this is basically introduction part  of the collections and in the coming sessions  

i will show you we will see how we can learn  uh what are the different type of collections  

how we can work with the array list hash map a  tree vector so all types of collections what are  

the different classes are available what are the  different type of interfaces are available so we  

will see all kinds of things from the collection  framework okay so this is the introduction part  

what exactly collection means collection  framework means and what is the difference  

between collection and correction framework and  why we need a collection framework and what are  

the different collection classes and interfaces  are available all right so that's all for this