Core java interview questions and answers for 3-5 years experience covered in this post:
Can we create a try block inside a try
block?
- Yes. You can have any number of nested try-catch blocks.
- Please refer to the below example.
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package simplifiedjava.crackedInterview; public class NestedTryCatchDemo {
public static void
main(String[] args) {
try {
try {
try {
}catch(Exception e) {
e.printStackTrace();
}
}catch(Exception e) {
e.printStackTrace();
}
}catch(Exception e) {
e.printStackTrace();
}
}
} |
Can I apply transient keyword to
primitive, static and reference variables?
- Primitive Variables: transient
keyword is applicable to primitive variables.
- Static Variables: technically
you can declare static variable as a transient but, it doesn’t make a sense
to make static variable as a transient because, transient key word is used
when you don’t want to consider a particular field for serialization. Static
variables by default not considered for serialization.
- Reference variable: Reference variable can be null and this variable doesn’t have any value
it has an address. So transient keyword is not applicable to reference
variables.
 
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Can we declare constructor inside inner
class?
-
Yes, we can declare a constructor inside the inner class.
- Please refer to the below example.
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package simplifiedjava.crackedInterview; public class Outer { public static void main(String[] args) { }
class
Inner{
int
a; int b;
public
Inner(int
a, int
b) {
this.a
= a;
this.b
= b;
}
}
} |
Which Collection objects implements
Queue interface?
- LinkedList implements Queue interface.
What is the difference between
SortedSet and TreeSet?
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|
SortedSet |
TreeSet |
|
1. |
SortedSet is an interface. |
TreeSet is a concrete class. |
|
2. |
SortedSet is an interface so cannot be instantiated. |
TreeSet can be instantiated. |
What is the difference between
Fail-Fast and Fail-Safe?
|
|
Fail-Fast |
Fail-Safe |
|
1. |
While traversing the collection object if someone is trying to
modify the value of the collection object, the iterator gets failed
immediately which is called Fail-Fast. |
While traversing the collections object if someone is trying to
modify the value of the collection object, the iterator never failed
immediately which is called Fail-Safe. |
|
2. |
It throws ConcurrentModificationException while modifying the
collection object during the iteration process. |
It doesn’t throw ConcurrentModificationException while modifying
the collection object during the iteration process. |
|
3. |
Performance is higher as compared to Fail-safe iterator. |
Performance is low as compared to Fail-fast iterator. |
|
4. |
Memory utilization of Fail-Fast iterator is lower. |
Memory utilization of Fail-Safe iterator is higher. |
|
5. |
E.g. ArrayList, LinkedList, HashSet. |
E.g. ConcurrentHashMap, CopyOnWriteArrayList,
CopyOnWriteArraySet. |
What is the difference between
HashTable and ConcurrentHashMap?
|
|
HashTable |
ConcurrentHashMap |
|
1. |
Thread will get whole object lock. |
Thread will get a bucket level or Setment level lock instead of
whole object lock. |
|
2. |
Only one thread is allowed to perform thread safe operation. |
Multiple threads are allowed to perform thread-safe operation at a
time. |
|
3. |
Every read and write operation require object level lock. |
Read operation can perform without lock and write operation can
perform by getting bucket level or Segment level lock. |
|
4. |
When one thread is performing read operation no other threads are
allowed to perform any operation on same object otherwise you will
get ConcurrentModificationException. |
When one thread is performing read operation other threads are
allowed to perform write operation on same object still you won’t
get ConcurrentModificationException. |
|
5. |
Iterator is Fail-Fast |
Iterator is Fail-Safe. |
|
6. |
Introduced in Java 1.0 |
Introduced in Java 1.5. |
List out some web servers and
application servers?
- Web Servers.
1. Apache Tomcat.
2. Lightpd.
3. Microsoft Internet Information Service.
4. Sun Java System Web Server.
5. Nginx.
6. Jagsaw.
- Application Servers.
1. JBoss
2. WebLogic
3. WebSphere
4. Glassfish
5. Oracle OC4J
Can you compare Inner classes and
lambda expression?
|
|
Inner class |
Lambda Expression |
|
1. |
An inner class can have a name. |
Lambda expression doesn’t have any name. |
|
2. |
An inner class can extend the abstract class. |
Lambda expression cannot extend the abstract class. |
|
3. |
An inner class can extend the concrete class. |
Lambda expression cannot extend the concrete class. |
|
4. |
An inner class can implement an interface that has multiple
abstract methods. |
Lambda expression can’t implement an interface that has multiple
abstract methods. |
What is Supplier functional
interface?
- The Supplier interface represents an operation that takes no argument and
returns a result.
- Please refer to the below example.
|
@FunctionalInterface
public interface
Supplier<T> {
} |
- Java interview questions and answers all MNC - Click here
- Basic core java interview questions and answers for freshers - Click here
- Core java interview questions for 3 years experience - Click here
- Core java interview questions and answers for 3-5 years exp - Click here
- Core java interview questions and Answers for 5 - 7 Years exp - Click here
- Basic Java Interview Questions and Answers - Click here
- Java interview questions and answers on oops - Click here
- Java interview questions and answers on Strings - Click here
- 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
Upcoming questions in next post:
61. Does finally block get executed if try or catch block has return statement. how the control flows in this situation.
62. What is the difference between Synchronization block and Synchronized method.
63. If your child class is serializable and parent class is not and child class is inheriting some properties of parent class, in that case can you serialize child class.
64. Can we declare constructor inside anonymous inner class.
65. What is SortedSet? What is the purpose of SortedSet?
66. What do you mean by Concurrency Level?
67. What is Generic Type Parameter.
68. What is the return type of apply method in Consumer functional interface.
69. What is the difference between Abstract class and Interface with Default methods.
70. What are the default methods defined in Function functional interface.
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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.
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