#26 Stack And Heap in Java

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In this lecture we are discussing:
1) Memory management in java and typed of categories to store data in memory.
2)What is stack ?
3)What is heap ?
4) where instance variable and local variable is allocated?
#1
In java we are managing our managing our memory using two data structure stack and heap.
two categories to store data in memory:
1) Stack data structure
2) heap data structure
#2
Stack is data structure which follow LIFO(Last in First Out) principle.
#3
heap is data structure which is used to store data in form of object and object is a collection of data and method.
#4
class Student{
int instVariable; //store in object and object created in heap
public static void main(String []args){
int localVariable=0; //local variable store in stack frame of method in stack area.
Student st=new Student(); //st is reference variable store address of new Student() object
}
public int add(int num1,int num2){
return num1+num2;
}
}
-- instance variable stored in object and object are in heap therefore we can say that instance variable created in heap.
-- method declaration and definition is present in object but actual implementation present in stack frame of stack.
-- local variable created in stack during call of method.
-- stack frame of called method is present in stack area.
-- st is reference variable created inside the current stack frame and it is reference variable store address of student object created in heap area.
-- new Student() create object in heap area and pointed by his reference variable.
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[@spidermanhomecoming001]

I just love you sir! I was confused for so long about heap and stack. Now its clear! U are a great teacher.

[@MsSWAGboss]

Thank you for the video :) I just started going into interviews again and this helped me get back to speed on the topic cause I had forgotten so much stuff throughout the year as a junior dev

[@ajiboladaniel9386]

The best Java teacher I've ever encountered in my life. You are awesome sir. The understanding of the concept is sooo seamless. It's like a miracle. Thanks soo much.

[@thefriendlymartian7317]

The best explanation anyone could ever give. As soon as I have a question in my mind, you call out that point and explain as if I asked the question in person. Just shows how perfectly the flow of the content is.

[@ferzandali1527]

I agree with u 100%

[@rushikeshbhujbal2480]

you are really great,this content is really helpfull and thanks for the notes that you are providing in description.

[@chairma_prabhu]

Thank you Navin for providing quality content like this.

[@zr0724]

wow , these tutorials are of next level for sure. thank you sir.

[@piotr2951]

No, we don't have multiple stacks (in a single thread), those are called frames. Those frames contain multiple data structures for storing local variables, operands, return addresses, constants.

[@Shubham-si6hd]

You are a life saver! Thank You

[@kapiljain359]

Really Nice explained. I am following Telusko since my collage time(2018). And now I am the Senior Software Developer in reputated Product company. Big Thanks Goes to Mr Naveen. Thank you Sir! I would like to request if you can make the playlist on AWS for Java Developers. It would be very helpful.

[@moaazsuliman7584]

From Egypt Thank You Very Much

[@ramenmanna6150]

Great video sir 😊 understand concepts very well ! love you sir 🥳

[@prakash1to7]

Great way of delivery Sir. Really motivating to learn. Keep on Rocking Sir :-)

[@mehedishuvo6257]

Well explained dear sir.Not only India but also all over the world students get benefited by your lecture,. This is a masterpiece that ever created by you.💜💜💜💜💜,,,,Love from Bangladesh dear sir.

[@sahinyusifli9756]

Thank you, it was so educative to me

[@bahasahli4151]

Simply awesome thank you 🌼

[@rosaliademartino7265]

nice and clear, thanks!

[@vishnusunil7446]

Amazing video.. thank you.

[@bharathsajan8926]

wonderfully explained thank you.

[@hridikasaha9519]

Excellent explanation

[@sn0wball13]

Thank you so much for this explanation!!!! :)

[@srushtishah8674]

When i asked my sir about instance variable he gave me such lame ans that I gave up on every being able to understanding it. Thanks!!

[@jackfrost8969]

excellent video. Keep it up.

[@danurarya0823]

Thanks for this sir, i like when you are describing how things work using a sketch. maybe it's just me but reading documentation that just only have text explanation is really confusing and to imagining it was really hard.

[@omkaromkar5215]

Same

[@valoranthighlights6374]

great explanation . love it

[@HocineFerradj]

U are a great teacher

[@Coding-Just]

Navin sir it's totally clear thanks a lot and sir i have to join your Java backend course but Saturday is my college sir and it's 3rd year bca 7 to 12 time is not convenient sir

[@nasamind]

Simply awesome

[@marcos_silvestri]

Splendid!

[@princeiiolaguera921]

Best course imo. Can you please create exercises so we can test our knowledge and skills so far? Thank you

[@rajnishchoubey2246]

Sir with reference to memory allocation in java can u plzz specify which of the variables have static memory allocation and which one has dynamic allocation and why

[@uchihasenpai5671]

Shouldn't obj be created after DATA in the stack? I mean should not OBJ be above data?

[@alexkuzmichev9051]

nicely explained! by the way, what program do you use to draw?

[@anupam6045]

best explanation sirr

[@MohdZaid-kv7yn]

Watching 2 hours before java developer interview

[@Avineshutube]

excellent !!

[@shyamchowdary5086]

I have a doubt. When we write a local variable in Java. It automatically allocates memory or it allocates after compilation? Please someone address this.

[@HarshPatel-so7gl]

incredible

[@adora6860]

maraming salamat tol

[@FEJAYACHANDRANK]

I have one doubt what if the class is static ... we cant create instance right at the case how is memory allocated

[@afsirlaghari3738]

Love you Naveen sir, from Pakistan.

[@unemployedcse3514]

this channel gives trustworthy content where other's just do for content sake

[@Trekshorts]

sir give us a quetion bank to practice this concepts, all quetions from basic to advance, so we can practice and implement the concepts or logic. your lectures are very easy to understand!! they are very helpful thank you!!!😃😃😃

[@user-ql5pe3xc3p]

I became a diehard fan for you sir ❤ love you and love your teachings sir

[@user-ql5pe3xc3p]

Thank You SIR ✨ This is my status today 🫴 ✨ Thank You SIR 💫

[@-RimuruTempest]

Hi, I have one doubt. What about the add method in stack? If we create two objects then the is there two add stack?

[@YuvarajRoll]

Sir how to get input from users in java

[@aaaeditzforever]

Super

[@actandrepeat]

Wow!

[@srinivasmb-re8km]

Where static variables are stored? static int in = 10;

[@ashutoshraj8668]

But sir methods of objects are stored in method area😢

[@abhishekmb7690]

Where the memory will be allocated for static members and static methods sir

[@HimakumarTellaboina]

Stack Area

[@abhiroy1993]

Will the 'add' method stack be reused for the 2 different objects or will it create a new 'add' method stack for obj1?

[@Krishna_script]

the new obj1 will reuse the add method which is there in the stack

[@saumyojitdas4212]

​@@Krishna_scriptpublic class Main { String s = "ABC"; public static void main(String[] args) { Main obj = new Main() ; System.out.println(obj.s); } } in this above code String object is created in heap and also of class. So 2 objects in heap. But isn't the string object Abc resides inside class object in the heap?that's why we are calling it obj.s

[@ummersiddique]

Which device is he using for drawing?

[@papo7936]

Could you replicate this video for python too?

[@Ounknown098]

i am comming from pw skills to watch full memory alliocaion

[@keinsent]

tqsmomg

[@saumyojitdas4212]

public class Main { String s = "ABC"; public static void main(String[] args) { Main obj = new Main() ; System.out.println(obj.s); } } in this above code String object is created in heap and also of class. So 2 objects in heap. But isn't the string object Abc resides inside class object in the heap?that's why we are calling it obj.s

[@ganesang7217]

I understand clearly, it's not an object. It's a reference type.like Car c = new Car() c is reference type, correct or not

[@partoon863]

If you guide us in Hindi we understand it more clearly

[@jatinsharma3792]

You beauty !!

[@rajattalreja9740]

One question - Exactly when is a stack created? When the method is created of when the method is called?

[@sachinkhatri1077]

I think stack memory allocated at run time. So it created when mehod is called. Thats why we get stackoverflow error at runtime instead of compile time.

[@banujan.b2479]

To be more specific the entire program has a stack. But when you call a method, each method creates a stack-frame in the stack.

[@mohokhachai]

Scope

[@mohokhachai]

Thier only one main entry function

[@mohokhachai]

Thier values is null

[@congdatt]

Stack: - Store local variables - Address of obj ( obj store in HEAP ) Heap: - Store obj. Have 2 sections: instance variables & .... (add(),....) Every method have own stack

[@mohokhachai]

Entry point

[@banujan.b2479]

Each method has own stack or stack-frame? 🙄

[@RamSingh-bi9tc]

But damaging one phone affect the user heart

[@ehteerk]

An instance variable is a variable that is specific to a certain object. It is declared within the curly braces of the class but outside of any method. The value of an instance variable can be changed by any method in the class, but it is not accessible from outside the class

[@muthukumarthangapandian8434]

both objects having same address only. if car1 =car2 class Car { String name; int cost; double mileage; } public class PassByReference { public static void main(String arg[]) { Car car1 =new Car(); System.out.println(car1.name); System.out.println(car1.cost); System.out.println(car1.mileage); car1.name="bmw"; car1.cost=1_00_0000; car1.mileage=17.5; System.out.println(car1.name); System.out.println(car1.cost); System.out.println(car1.mileage); Car car2=car1; System.out.println(car2.name); System.out.println(car2.cost); System.out.println(car2.mileage); car2.name="honda"; car2.cost=1_00_000; car2.mileage=18.5; System.out.println(car2.name); System.out.println(car2.cost); System.out.println(car2.mileage); System.out.println(car1.name); System.out.println(car1.cost); System.out.println(car1.mileage); System.out.println( car1.hashCode()); System.out.println( car2.hashCode()); System.out.println(car1); System.out.println(car2); } }

[@navingautam8878]

same name haha

[@ahmedyoussef7923]

It is wrong. we don't have multiple stacks in a single thread.

[@khanhgiapham-mi4hg]

please speak English sir