2. How Java Program Works and its 3 Important Components (JVM, JRE and JDK) with Example

➡️ Notes link: Shared in the Member Community Post (If you are Member of this channel, then pls check the Member community post, i have shared the Notes link there)

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In this video, i explained in detail about the 3 important components of Java:
- JVM (Java Virtual Machine)
- JRE (Java Runtime Environment)
- JDK ( Java Development Kit)

I also explained, from where to download the Java.

You will also get information about :
- JSE (Java Standard Edition)
- JEE ( Java Enterprise Edition)
- JME (Java Micro Edition)

And at last we will write our FIRST JAVA PROGRAM and will set how it works.

#java #objectorientedprogramming #firstjavaprogram

[ankitshaw_]

If any one wants to know why main method is void so the short answer is because it does not return anything but if you want to know in depth about why main method in java returns void but in C/C++ it returns 0, then this is the reason behind it :- The C and C++ program which return int from main method are processes of operating system . The int value returned from the main in C and C++ is exit code or exit status.
Exit Code 0 --> means successful termination
Exit Code non-zero ---> indicates an error
The parent process of any child process keeps waiting for the exit status of the child and after receiving that exit status of child it clears up the child process from the process table and free the resources allocated to it . That is why it becomes mandatory for C and C++ program to pass their exit status . However, the java program runs as a main thread in JVM. The java program is not even a process of operating system directly this is why main method of java is not designed to return an exit status. However, JVM is a process of Operating system and JVM can be terminated with a certain exit status with help of System.exit(int status).

[priyamf]

Thankyou so much for this series. Why i am learning from you and not the big channels, because I see that experienced engineer in you, which even i look forward to be in the future. I believe, knowledge with experience is something really amazing. Currently preparing for my on-campus placements and this series is really helping. Just a question, if i buy your membership, are more JAVA videos available there? thanks.

[ashishshandilya]

I am working from rival for PayPal, which until now written core components in c++, with influx from folks from PayPal we are now moving to Microservices. Hence forced to learn java and spring.Hope this one will ramp me up. :(. Thanks for the content.

[fv]

Nice lecture dude. One question: if JVM reads the code line by line and converts to machine code( which is a definition of an interpreter ), could you tell why is it called "Just in time compiler".

[ManishVerma-sinv]

Hello Shrayansh,
I have one doubt...If I have written a program in Java and wants to run it in a mobile phone...does the phone require JVM or JRE ???

[soumyasatish]

Hi Shreyansh, which ide are you using in this video? Can you recommend an IDE for Windows?

[knowledgeascend]

Hey Srayansh, Great video.
Just a small query, does JRE contains bytecode of class libraries or will the java code contained in them will be converted to Byte code by java compiler ?

[sumitbasu]

Hi Srayansh, may be it is not a valid question but still let me ask it.
If the jvm converts the bytecode to machine code and cpu will execute the machine code, then how JVM invokes/calls the main method at runtime? It should be CPU that calls the main method r8?

[akarshkumarsrit]

if my code doesnt use any java lib it would just need jvm to run right ?

[suryaprakash]

bro, pls put a specific videos about jar, war and ear files

[singhji]

For LLD WILL U ADD VIDEOS OF PAYMENTS APP AND FOODING APPS( ZOMATO SWIGGY DESIGN)

[akhilbhatia]

can i have notes of these lecture for quick interview revision ?

[yogendramaurya]

Started today, let's see how far I go.🤞

[Badalkumar-meok]

How to get the .class file from a .java file in eclipse

[sambhav]

If jre already has class libraries then what is meant by "jdk has programming language"? jdk has compiler and debugger and that is a valid point but not able to understand difference between class libraries in jre and programming language in jdk?