Disclaimer: This presentation is prepared by trainees of
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
• Java programming language was originally developed by Sun
• Object Oriented : In Java, everything is an Object based.
• Platform independent.
• A virtual machine (VM) is a software implementation of a
machine (for example, a computer) that executes programs
like a physical machine.
• Virtual machines are separated into two major
system virtual machine and process virtual machine.
• A Java virtual machine (JVM) is a process virtual
machine that can execute java byte code.
• JVM converts Java byte code into machine language and
• JVM is platform dependent : JVMs are available for many
hardware and software platforms.
• JVM gives Java the flexibility of platform independence.
Diagram of JVM
Java source code Byte codeJava compiler
Java Virtual Machine
Computer Operating System
Byte code loaded into JVM
Class loader sub
• All Java virtual machines include one class loader that is
embedded in the virtual machine.
• Class loader loads java classes into java virtual machine.
• Class loader reads bytecode and creates the instance of
• The execution engine helps JVM to convert bytecode into
• A mechanism responsible for executing the instructions
contained in the methods of loaded classes.
• Stack stores various method arguments and local variables of
any method .
• There are three registers that help in stack manipulation.
– Vars register
– Frame register
– Optop register
Sections in stack
• Local variable
– This section contain all local variable being used by current method.
• Execution environment
– Execution section is used to maintain the operation of stack itself.
• Operand stack
– The operand stack is used as a work space by bytecode instruction.
• This is the area where byte code is placed.
• The program counter points to the next instruction in the
• After the execution of an instruction , JVM set pc to next
Garbage Collected Heap
• The object in java program are stored in Garbage collected
• Arrays in java program are objects, hence they also stored
• Java does not have a free operator to free any previously
• Java done this automatically by Garbage collection
• JRE is an acronym for Java Runtime Environment.
• Java Runtime Environment contains JVM, class libraries, and
other supporting files.
• It does not contain any development tools such as compiler,
• JDK is an acronym for Java Development Kit . It physically
exists . It contains JRE + development tools.
• Just-in-time Compiler -is the part of the Java Virtual Machine
(JVM) that is used to speed up the execution time.
• JIT compiles parts of the byte code that have similar
functionality at the same time, and hence reduces the amount
of time needed for compilation.
Is java a compiled or interpreted
• Java is a compiled language because the source code is
converted into byte code.
• Java is an interpreted language because the byte code is
interpreted by a virtual machine.
Want to learn more about programming or Looking to become a good programmer?
Are you wasting time on searching so many contents online?
Do you want to learn things quickly?
Tired of spending huge amount of money to become a Software professional?
Do an online course
We put industry standards to practice. Our structured, activity based courses are so designed
to make a quick, good software professional out of anybody who holds a passion for coding.
Follow us @ twitter.com/baabtra
Like us @ facebook.com/baabtra
Subscribe to us @ youtube.com/baabtra
Become a follower @ slideshare.net/BaabtraMentoringPartner
Connect to us @ in.linkedin.com/in/baabtra
Give a feedback @ massbaab.com/baabtra
Thanks in advance
www.baabtra.com | www.massbaab.com |www.baabte.com
Emarald Mall (Big Bazar Building)
Mavoor Road, Kozhikode,
Ph: + 91 – 495 40 25 550
NC Complex, Near Bus Stand
Ph: + 91 – 495 40 25 550
Hilite Business Park,
Start up Village