What is JVM,JRE,JDK ?

-

What is JVM?

  • JVM stands for Java Virtual Machine.
  • JVM is the virtual machine that runs under the java bytecode.
  • The JVM doesn't understand the java source code that is why you compile your ".java" files to obtain ".class" files that contains the bytecode understood by the JVM.
  • The same bytecode gives the same results makes java program platform independent language.
  • The main advantage of java program is write the code once and run it anywhere.(i.e run in any operating system like windows,Linux,Mac..)
  • let's try to understand the work of JVM- we write the code in any text-editor,save your program in ".java"(Ex- Sp.java). When you compile your java program using "javac" compiler, the compile convert your code into bytecode, which is exactly understand by the JVM.

What is JIT compiler?

JIT compilers is the part of JVM which increases the speed of execution of java program.

What is JRE?

  • JRE stands for Java Runtime Environment.
  • JRE provides the libraries ,the java virtual machine and other components to run applets and applications written in the  java programming language.
  •  JRE=JVM+set of libraries+other additional files
  • The JRE does not contain tools and utilites such as compilers or debuggers for developing applets and applications.

What is JDK?

  • JDK stands for Java Development Kit.
  • JDK is a superset of the JRE and contains everything that is the JRE,puts tools such as compilers and debugger necessary for developing applets and applications.
        JDK=JRE + Development tools
        JDK=(JVM + Set of libraries+ other additional files)+Development tools


Let's see the basic java program,
Ex-
         class Sp
        {
            public static void main(String[] ar)
                {
                    System.out.println("Welcome to Sp:)Learn");
                }
        }
  • Save the program in your local system in name "Sp.java".
  • For compile use "javac Sp.java".
  • After successfully compilation the compiler create the "Sp.class" file for JVM, further step is run the program. for run the code we write "java Sp".
  • The output of the above program is:                                                                                Welcome to Sp:)Learn
Let's discuss the parts of the above java program:
  • Public: Public is a keyword of access modifier which represents visibility. It means it is visible to all over the class.(we can discuss about the access modifiers in our further topics)
  • Class: It is a keyword used to declare class in java.
  • Static: It is also a type of keyword. If we declare any method as static it is known as static method. The core advantage of static method is that there is no need to create object to invoke the static method.
  • Void: void is the return type of the method. It means it doesn't return any value.
  • Main: main represents start-point of the program. It means every java program start its execution from main method. It is the entry point of the java program.
  • String[] ar : it is used for command line argument.
  • System.out.println(""): it is used to print the statement.

---Thank You---

Comments

Post a Comment

Popular posts from this blog

What is C# ?

-
Image
What is C# ? C# is pronounced "C-Sharp". C# is an elegant and type save object oriented language created by microsoft. That enable develops to built a veriety of secure & robust application in the .Net Framework. C# has roots from the C family, and the language is close to other popular languages like C++ and Java. The first version was released in year 2002. The latest version. C# -8 was released in sept 2019. C# used for- Mobile Application Desktop Application Web Application Web Services Websites Games VR Database Application And much more... Why we use C# ? It is one of the most popular programming language in the world. It is easy to learn and simple to use. It has a huge community support. C# is an object oriented language which gives a clear structure to programs and allows code to be reused, lowering development costs. As C# is close to c,c++ and java. It makes it easy for programmers to switch to C# or vice versa.
Read more

Communication Skills

-
Image
Communication skills allow to understand and be understand by others.Being able to communicate effectively is one of the most important life skills to learn.Communication at its simplest is the act of transferring information from one place to another. Effective communication sounds like it should be instinctive. But all too often, when we try to communicate with other something goes different. We say one thing and the other person hears something else and at this time misunderstandings, frustration and conflicts occur. This can cause problems in your home,school and work relationships. The ability to communicate effectively with superiors,colleagues and staff is essential no matter what industry you work in . Workers in the digital age must know how to effectively convey and receive messages in person as well as via phone, email any social media platform. The communication skills will help you get hired, to achieve promotions and a successful person in your field .
Read more

7 Habits of Highly Effective People Book Summary

-
Image
7 Habits of Highly Effective People by Stephen R. Covey is a self motivated book for all people.When we read the book ,it can teach us both personal and professional effectiveness by changing your view of how the world works and how your habits can change you.If we adopted the habits well ,it lead us success. Stephen see a big success and want to know how he did it by adopting the habits.These habits are: 1.Be Proactive: Proactive means to keep yourself stable is a first important aspect. Don't react or create any situation of your problem. At the same time think about it and create a better solution of your problem.         Reactive: They blame other for their problem.They can't accept the problem & gives to other.         Proactive: They take their all responsibility & can't blame to others for their problems. They think about their problems & find solution. "Focus on things you can change , Not on the things which you can't change.&q
Read more