jvm

[RAMA SUBRAMANIAN]

hi to everyone !!
where does the JAVA VIRTUAL MACHINE resides?
Does it resides in the java-enabled-web browser or in the operating system of the computer?
[This message has been edited by RAMA SUBRAMANIAN (edited December 08, 2000).]

[Frank Carver]

A JVM may be in one or more of several possible places. Some Browsers include their own JVM; A JVM is installed on your machine whan you install a Java JDK or SDK; A JVM is installed on your machine when you install a Java JRE; Some other software has an internal JVM (Oracle 8 databases, for example); Some development tools include their own JVM (IBM Visual Age, Asymetrix Supercede, for example). Some operating systems come with a JVM pre-installed (some versions of Windows, some versions of Linux, recent versions of Solaris etc.)
My main development machine probably has at least five different JVMs installed at the moment.

[ankur rathi]

What they exactly are :
What exactly difference b/w this ?

1] JDK
2] SDK
3] JVM
4] JRE

What type of implementation they have ?
What is needed in which situation ?

Please give some good answers bcoz it will be very good for us ( all rancher ) to get deep information abt language .

[Daksh Sharma]

Hello i have extracted all these from the net.. have a look it explains all... I have repeated some lines so as to clear concept

Right now u r having java right installed on ur m/c that u can term as JDK and ur JRE is a subset(part of JDK) jre does not have javac it is like minimum environment needed for running java stuff. JVM is a part of JRE

JDK includes JRE which consists and jvm and other things..

SDK used to be called JDK before..


JDK means Java Development Kit

The Java Development Kit is a software development package from Sun Microsystems which implements a basic set of tools which are required in order to develop, test and debug Java applications and Applets. This software is freely downloadable from the internet

Like if any one asks u what is jdk ur answer shud be it is a s/w that includes APIs (application programming interfaces ) and tools that developers need inorder to build applications for version which came after java2 platform..

It is the basic set of tools that is needed to write and test and debug the java applications

If u say that it is a s/w development package then that is also perfectly all right

All ur javac (the java compiler is present in it) ... i hope u can get my meaning...

for running java applications u need javac,java interpreter and various other things u can check it by going to your java installation directory and look under jdk/bin path..

JVM
Stands for Java Virtual Machine

Before reading check this post..
http://www.javaranch.com


JVM is contained under JRE

Machine - An abstract computing machine, or virtual machine, JVM is a platform-independent programming language that converts Java bytecode into machine language and executes it. Most programming languages compile source code directly into machine code that is designed to run on a specific microprocessor architecture or operating system, such as Windows or UNIX. A JVM -- a machine within a machine -- mimics a real Java processor, enabling Java bytecode to be executed as actions or operating system calls on any processor regardless of the operating system. For example, establishing a socket connection from a workstation to a remote machine involves an operating system call. Since different operating systems handle sockets in different ways, the JVM translates the programming code so that the two machines that may be on different platforms are able to connect.


JVM Is responsible for making java code platform independent

It is used to converting the javabyte code into machine language and executing it...

It can be termed as a Computing machine or Virtual Machine a software again


JRE :

JavaTM runtime environment)

A subset of the Java Development Kit (JDK) for users and developers who want to redistribute the runtime environment. The Java runtime environment consists of the Java virtual machine (JVM), the Java core classes, and supporting files.


The Java Runtime Environment (JRE) is the minimum standard Java platform for running applications written in the Java programming language. It contains the Java Virtual Machine, Java core classes, and supporting files. The JRE does not contain any of the development tools (such as appletviewer or javac) or classes that pertain only to a development environment
JRE


SDK

A set of programs that allows software developers to create products to run on a particular platform or to work with an API

A kit that programmers can use to create new applications.

A software development kit (SDK) for creating Java programms of version 1.2 Sun, JavaTM 2 Platform, Standard Edition
An environment distributed by Sun Microsystems that includes the Java compiler. SDK used to be called JDK.


jdk includes jre and jre includes jvm

[ankur rathi]

It was too ( infect 3 ) good explanation ...
JDK includes JRE includes JVM .
Sun provide JDK at free of cost .

One more thing is it possible to install only JRE ( we have all the class files in hand & we dont need to compile any java file now )

Is it possible to install only JVM ( but what I will do with this ?? who will convert byte language(.class file) to execution language (.exe file) )

Thanks .

[Daksh Sharma]

Speaking practically JDK is essential for developers, which comes along with library packages to develop Software programmes.

While JRE is minimal set of programmes which executes the java class files developed by the software developers

Your questions answer shud be no for me

Best thing u can do is try running on jre a java program

[Daksh Sharma]

JRE has to meet JVM specification ... but that is not in JDK coz JVM is embedded in it...

Thus this makes running files on JRE alone diff.

[Layne Lund]

Originally posted by rathi ji:
What they exactly are :
What exactly difference b/w this ?

1] JDK
2] SDK
3] JVM
4] JRE

What type of implementation they have ?
What is needed in which situation ?

Please give some good answers bcoz it will be very good for us ( all rancher ) to get deep information abt language .

It looks like the above explains what each of these are quite well. However, the actual meaning of these acronyms seems to be missing, so I thought I'd post them

JDK = Java Developer's Kit
SDK = Software Developer's Kit
JVM = Java Virtual Machine
JRE = Java Runtime Environement

The term SDK is not unique to Java. However, in this context, SDK and JDK are often used interchangeably.

Keep Coding!

Layne

[Daksh Sharma]

Lund's Post (Extract)

It looks like the above explains what each of these are quite well. However, the actual meaning of these acronyms seems to be missing, so I thought I'd post them

My dear Lund if u look at my answer properly i have mentioned the acronyms for all the 4 terms... U r requested to go thru it again..

[Layne Lund]

Originally posted by Daksh Sharma:
Lund's Post (Extract)

It looks like the above explains what each of these are quite well. However, the actual meaning of these acronyms seems to be missing, so I thought I'd post them

My dear Lund if u look at my answer properly i have mentioned the acronyms for all the 4 terms... U r requested to go thru it again..

Doh! :roll: I must have missed that when I scanned through your post. My deepest apologies.

Layne

p.s. In my culture, the given name comes first. Please call me Layne