Part 4
Interview questions on JVM for experienced covered in this post:
What is JVM?
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JVM stands for Java Virtual Machine.
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Implementation of JVM is JRE(Java Runtime Environment).
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JVM is responsible to manage memory, creating an object,
destroying objects, instantiating classes etc.
What is the difference between JDK, JRE and JVM?
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|
JDK |
JRE |
JVM |
|
1. |
JDK stands for Java Development Kit. |
JRE stands for Java Runtime Environment. |
JVM stands for Java Virtual Machine. |
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2. |
JDK is superset of JRE. |
JRE is a subset of JDK. |
JVM is a subset of JRE |
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3. |
JDK is a software development kit to develop applications in
java. |
It is a software bundle that provides java class libraries with the
necessary components to run java code. |
JVM executes java byte code and provides an environment for
executing it. |
|
4. |
JDK enables developers to create a java program that can be
executed and run by the JRE and JVM. |
JRE is a part of java that creates the JVM. |
It is the java platform component that executes source code. |
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5. |
JDK containes the tools to debugging, developing and monitoring the
code. |
It contains the class libraries and other supporting files that JVM
requires to execute the program. |
Software development tools are not included in JVM. |
How JVM reclaims memory?
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Memory reclaims means simply deleting the unreferenced
objects.
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JVM identifies the unreferenced objects and marks them.
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After marking the objects JVM runs finalize() method to
release the resources acquired by unreferenced objects.
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Once releases all the resources acquired by unreferenced
objects JVM simply swipes them from memory.
 
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Can we trigger the garbage collection from java code?
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Yes, we can just recommend to JVM for garbage collections.
But we cannot force JVM.
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We can recommend invoking the System.gc() method. But, it's
not guaranteed garbage collectors will execute.
What is the permsize? What is the importance of permsize? Where we can modify the permsize?
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Permsize can be defined as Permanent Space.
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Permsize is an initial value of permanent space which is
allocated at JVM startup.
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java -XX:PermSize=512 MyProgram.
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Java interview questions and answers all MNC - Click here
-
Basic core java interview questions and answers for freshers
- Click here
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Core java interview questions for 3 years experience - Click here
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Core java interview questions and answers for 3-5 years exp
- Click here
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Core java interview questions and Answers for 5 - 7 Years exp
- Click here
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Basic Java Interview Questions and Answers - Click here
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Java interview questions and answers on oops - Click here
-
Java interview questions and answers on Strings - Click here
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Java interview questions on exception handling - Click here
-
Interview questions on multithreading in java for experienced
- Click here
-
Interview questions on serialization in java for experienced
- Click here
-
Interview questions on inner class in java for experienced
- Click here
-
Interview questions on Collections in java for experienced
- Click here
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Thank you techies for visiting this blog. I hope you enjoyed this blog and got more technical knowledge. I have tried to cover all types of questions and provided examples tested on eclipse as much as I can. Guys, please don’t just mug up the questions and answers. Try to clear your concepts with examples. Try to write a code on eclipse once you read the concepts. It will help you to memorize the concepts for a very long time. Simultaneously you will be prepared for interview programs as well. It will help you to survive in the IT sector for a long time. It may be easy to crack an interview but it's really tough to survive in the IT industry with inadequate knowledge and skills. I have collected all the questions from actual interviews attended by my friends, colleagues, college mate and classmate. I have covered frequently asked questions as well as challenging questions. I have included many programs to understand the concept thoroughly. I will try to explain the concept with the help of a real-time program in eclipse. You can share more questions which are not covered in this blog or post. Always welcome your suggestions and queries. I will definitely try to resolve it. Please comment your queries and new set of questions under the comment sections. I will create a new post for those questions.
My total experience is 10. Initially I had worked on
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