Open App

IT & Software Exam > IT & Software Videos > How Java Virtual Machine Works

How Java Virtual Machine Works Video Lecture - IT & Software

FAQs on How Java Virtual Machine Works Video Lecture - IT & Software

1. How does the Java Virtual Machine (JVM) work?

The JVM is responsible for executing Java bytecode, which is the compiled form of Java source code. It acts as an intermediary between the Java applications and the underlying operating system, providing a platform-independent execution environment. The JVM consists of various components such as the class loader, bytecode verifier, interpreter, just-in-time (JIT) compiler, and garbage collector. It loads the bytecode, verifies its integrity, interprets it, and dynamically compiles frequently executed code segments for improved performance.

2. What is the role of the class loader in the Java Virtual Machine?

The class loader in the JVM is responsible for loading Java classes into memory. It locates and reads the bytecode of a class from the file system or network, and then creates an internal representation of the class. The class loader also performs tasks like resolving dependencies between classes, linking classes together, and ensuring the integrity of the loaded classes. It follows a hierarchical delegation model, where it first delegates the class loading request to the parent class loader before attempting to load the class itself.

3. How does the bytecode verifier ensure the security of the Java Virtual Machine?

The bytecode verifier in the JVM plays a crucial role in ensuring the security of Java programs. It analyzes the bytecode of a class before it is executed and checks for any potential security vulnerabilities or violations of the Java language rules. The bytecode verifier examines the structure and consistency of the bytecode, confirms that the bytecode does not perform illegal operations or access unauthorized resources, and enforces memory access restrictions. By verifying the bytecode, the JVM prevents malicious or erroneous code from causing harm to the system.

4. What is the difference between interpretation and compilation in the Java Virtual Machine?

Interpretation and compilation are two different approaches used by the JVM to execute Java bytecode. Interpretation involves the JVM executing the bytecode instructions one by one, translating them into machine code at runtime. This approach provides platform independence but can be slower. On the other hand, compilation involves translating the bytecode into machine code before execution. The JVM uses a just-in-time (JIT) compiler to identify frequently executed code segments and dynamically compile them for improved performance. This hybrid approach combines the benefits of both interpretation and compilation.

5. How does the garbage collector work in the Java Virtual Machine?

The garbage collector in the JVM is responsible for automatic memory management. It identifies and frees up memory that is no longer in use by Java objects, thus preventing memory leaks and manual memory deallocation. The garbage collector uses various algorithms, such as mark-and-sweep, copying, or generational collection, to determine which objects are reachable and which are not. It traverses the object graph, starting from the root objects, and marks the reachable objects. The unreachable objects are then freed up and their memory is reclaimed for future use.

Text Transcript from Video

Can you tell me how Java Virtual Machine works?
Java Virtual Machine or JVM has the motto
write once, run everywhere.
I know the motto, but I do not understand
the how.
Because Java Virtual Machine compiles code
at real time, AKA just in time compilation,
you see slightly slower execution.
But since you run JVM directly on your computer,
this ensures that Java runs on every type
of device.
And generates just as many errors, too.
JVM creates a runtime instance every time
you start a Java application.
It is supposed to kill the instance when the
application completes.
It manages to crash often enough.
Java Virtual Machines terminate the JVM runtime
when all non-daemon threads are running.
If the daemon threads are running, it still
goes on, but JVM can kill an application through
the security manager using the exit method.
When something is found wrong by security,
head to the exits.
But how does JVM work?
Java source code is saved as .java source
files, but it is translated into Java bytecode.
When you run Java, the Java Virtual Machine
converts the bytecode into machine instructions.
It has to be good, because a lot of languages
now use the JVM.
But won't it crash if I have more than one
running?
Each Java application uses its own Java Virtual
Machine.
So JVM is virtual, and I can have more than
one JVM running?
That's right.
So I could have lots of different types of
applications using JVM, and it won't error
out.
No more than usual.
There are several versions of JVM, too, though
the most common version of JVM was written
by Oracle, its creator.
So JVM is an execution method for any language
that is written to use it.
And JVM is compatible with almost any device
because it compiles code in real time using
a native method interface and native libraries.
It's a code translator.
That's a fair way of looking at it.

Related Exams

IT & Software IT & Software IT & Software

About this Video

Jan 12, 2025 Last updated

How Java Virtual Machine Works for IT & Software2025 is part of IT & Software preparation. The notes and questions for How Java Virtual Machine Works have been prepared according to the IT & Software exam syllabus. Information about How Java Virtual Machine Works covers all important topics for IT & Software2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises and tests below for How Java Virtual Machine Works.

Introduction of How Java Virtual Machine Works in English is available as part of our IT & Software preparation & How Java Virtual Machine Works in Hindi for IT & Software courses. Download more important topics, notes, lectures and mock test series for IT & Software Exam by signing up for free.

Description

Video Lecture & Questions for How Java Virtual Machine Works Video Lecture - IT & Software - IT & Software full syllabus preparation | Free video for IT & Software exam.

Information about How Java Virtual Machine Works

Here you can find the How Java Virtual Machine Works defined & explained in the simplest way possible. Besides explaining types of How Java Virtual Machine Works theory, EduRev gives you an ample number of questions to practice How Java Virtual Machine Works tests, examples and also practice IT & Software tests.

Objective type Questions

past year papers

ppt

Sample Paper

Important questions

study material