This document provides information about the Java Virtual Machine (JVM) and how it works. It discusses that the JVM is an execution engine that runs compiled Java byte code. It also summarizes that Java is distributed in two packages - the JDK for developing applications and the Java Runtime Environment for running programs. Finally, it briefly explains the key steps of how the JVM works - a Java program is written, compiled to a class file containing bytecodes, and these bytecodes are interpreted and translated into native machine code by the JVM to run on any platform.

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baabtra as a part of mentoring program. This is not official
document of baabtra –Mentoring Partner
Baabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt .
Ltd

3. Week Target Achieved
1 30 21
2 30 22
3
Typing Speed

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5. Java Virtual Machine
JVM is an execution engine that runs compiled
Java byte code

6. JAVA IS DISTRIBUTED INTO TWO
PACKAGES

7. • JDK is a set of tools for developing Java
applications.
• Java Run-time Environment helps in running
the programs.
• JVM interprets Java programs and allows them
to run on any platform
• JIT is a module,which helps in compiling
certain parts of byte code into the machine
code for higher performance.

8. 8
How does JVM work?
• A Java program is written
• The program is compiled
• A class file is produced containing
bytecodes
• The bytecodes are interpreted by the
JVM
• The JVM translates bytecodes into
native machine code
Compiler
Java Virtual Machine
Native Machine Code
public class HelloWorld {
public static void main(String args[ ]) {
System.out.println(“Hello World!”);
}
}
Source Code
Class File
Bytecodes

9.  When JRE is installed it contains
JVM and JIT and the class libraries
 When JDK is installed it also contains the
JRE, JVM and JIT apart from the compiler,
debugging tools.

10. comparison between jvm ,jre and jdk
1) JRE and JDK come as installer while JVM are bundled
with them.
2) JRE only contain environment to execute java
program but doesn’t contain other tool for compiling
java program.
3) JVM comes along with both JDK and JRE and created
when you execute Java program by giving “java”
command

11. Just In Time Compiler
JIT is a module inside the JVM which helps
in compiling certain parts of byte code into
themachine code for higher performance.
Note that only certain parts of byte code will
be compiled to the machine code, the other
parts are usually interpreted and executed

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