Java Classes, Objects, Stack and Heap Memory Explained - Part 1 of 2
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- เผยแพร่เมื่อ 5 ก.ค. 2024
- Hi There,
This video is explanation of basic but very important java concepts Class, Object and how the Objects are stored under the hood on Heap Memory
man, am I glad I found this channel. All other channels just show you the code and sometimes, what it does. But NOBODY tells you what happens in the background.
I'm taking my OCA in a couple of months and I believe I've just found the perfect resource to help me ace the test. Good work.
I was confused about memory management in java...now all clear. Thank you for an amazing presentation.
That was really awesome presentation, please keep going sir.
This is what i actually need. Thanks!
Thank God i found this gem 🙏❤️ thanks sir.
Glad it helped.
very nice explanation , i understand clearly .
Well explained, very good job!
Awesome job, man, thank you!
Awesome! its help me alot! Thank you!
I watched, I benefited, I absolutely adored, I subscribed... Thanks a bunch...
Appreciate it. Thanks for the feedback.
very well explained
Great!! thanks a lot
Sooo good!
thankss
Yours is one of the best videos I watch to get a clear understanding of Java. But Java has become the basic or back bone, so can you create more videos detailing Spring Cloud, micro services etc
Hi Shama, thanks a lot for your feedback. Yes I do have plans to create more videos on whats used on actual job, the reasonI started with this is to get the basics strong and most of the interviews will have mainly basic questions cleared first. But I will get there eventually. Thanks
The explanation was too good, can u pls create a playlist. That'll be very much appreciated.
Thanks for the great feedback. I have created multiple playlists on different topics. Please feel free to go to my account and go over your topic of interests.
Nice way of explanation
Thanks for feedback. Glad it was helpful.
awesome
Thanks Praful, for the feedback appreciate it!
Thanks you sir it was fab✨✨✨✨
Thanks a lot. Appreciate your feedback.
Hi sir, Your teaching style is very effective, and the visuals you provided have greatly aided our understanding of memory management. Could you please explain the following concepts with visuals?
After writing the Java code with .java extension
we will compile it using a Java compiler (like javac)
After compilation, the bytecode is loaded into the method area of the JVM . The method area stores class-level data like method bytecode, static variables, and type information. Here I would like to know how these data will be saved in Method area with your style of visuals ?
Static variables are allocated memory space in the method area. They exist for the entire duration of the program and are initialized with default values (if not explicitly initialized) when the class is loaded.
Static methods are also loaded into the method area. When a static method is invoked, its local variables are allocated memory on the stack. These variables exist only for the duration of the method invocation.
When the main method is called (which is static), it too is loaded into the method area. As the main method is executed, any local variables declared within it are allocated memory on the stack.
Please kindly explain the above concerns with visuals, how you explained for object creation
Thank you sir
Thank you for the suggestion I will try to create a video with this level of detail. Ones I do I will post the link here. Hopefully soon. Thanks.
Hi There, I have prepared a video on your demand please have a look and see if its clearer now. Happy to answer any questions 😊
Java Stack, Heap and More
th-cam.com/video/y0J0hS158sg/w-d-xo.html
Sir please make vedio on how array stores in heap
Hi Jahnvi, sure I will create one soon and let you know. Give me a couple days I will ping back ones ready.
It's not better it is the best ☺️ .... I have one doubt here when we create an object using a new keyword the next is person() right what is this actually I know this is a constructor but what it does exactly
Any information will be helpful to all please share your knowledge ☺️
Hi Mahendra, so think of constructor as a special method where you can pass in parameters to set the properties of the object. When new Person() is executed the constructor of its parent, Object (note the capital O) is called and that way JVM knows to allocate space in the heap. How exactly it happens we as developers don’t really need to know but if you are curious can look at other resources, sorry I don’t know more low level than that.
Please make more video on this topic
Hi Naman, I have already covered more topics on the basics have a look at my ocp certification playlist.
Student a = new Student();
When we create a object like this , the jvm loads all the object data(like properties, methods)in the form of byte code in a heap memory area.
In stack memory, frame is Creted for main method from that the code executes line by line what is containing in that
The jvm converting the byte code of instructions containing in main method into binary language .
But some of them says the entire object is loaded in physical memory (means all object data in binary form )please clarify sir which one is correct......
Sorry for the delayed response, if I understand your question correctly you are asking if the data is loaded in memory in byte code or binary format? Did I get that correctly?
In general think of Byte code as java program that the computer can understand. The code you write in the .java file is converted into byte code. The instructions mentioned byte code are understood by JVM. Byte code is stored in .class files.
When it comes to loading the java into memory its all done in binary format byte code does not come in play.
Please let me know if I have answered your question or you have more followup questions. Thanks.
@10:05, Um, why does the STACK keeps occupying its memory, when it's only a local variable pointing to the heap?
Added remarks: main() and p.sayYourName() are the only two added in the stack right, the rest are local and pointers. then at the end of the scope of main() the java GC will do its thing.
The local variables will live until the the surrounding method (main in our case) is being executed. As soon as the jvm sees the closing curly brackets of main method the local variable wont be alive anymore and which is when stack would be cleared. In short as long as a local variable is in scope it will stay on stack. Hope it makes sense if not happy to explain again.
I do have a questions, what would happened to the heap or to the instance object if its contructor call a function/behavior? And so Where do this function live (stack or heap)?
Good question. The function/behaviour live on a special type of memory called method area. A method/behaviour is just set of instructions and not a storage of value like a variable. I think this special area on the heap but don’t really count as heap. As a developer you don’t have to care where it live exactly JVM will take care of it. Hope that clears the concept.
Sir please make vedio on , inheritance
Noted. I will create one as soon as I can. Thank you!
@@harrygill6169 thank you sir
Please Zoom the application for more clarity
Hi Deepti, thanks for your inputs. This was one of the very first tutorial I made so have got better at it now.
Too small on mobile phone...
Appreciate your feedback. I will take this in account in future. Thanks much.