Java Interview Questions for 5 years Experience

Top Java interview questions for 5 years experience 

For a Java professional with five years of experience, the java interview questions mentioned in this blog post cover a wide range of fundamental and advanced concepts in the Java programming language. These java interview questions aim to assess the candidate’s understanding of core Java concepts, object-oriented programming principles, exception handling, multithreading, memory management, and more.

They also delve into topics such as inheritance, polymorphism, interfaces, and annotations. By exploring these areas, the interviewers can gauge the candidate’s depth of knowledge, problem-solving abilities, and familiarity with best practices in Java development. 

With these Java interview questions for 5 years experience, the interviewers can identify candidates who possess a strong foundation in Java programming and are capable of handling complex scenarios and challenges that arise in real-world Java development projects.

Also Read: Top Java Interview Questions for freshers

Let’s get started.

Java Career Outlook:

Java developers enjoy a promising career outlook due to the language’s widespread adoption and its relevance in various industries. Here are some key statistics that emphasize the importance of Java in today’s job market:

  1. High Demand: Java consistently ranks among the most in-demand programming languages. Companies across sectors, including finance, e-commerce, healthcare, and technology, seek Java developers for their projects.
  2. Versatile Application: Java’s versatility allows developers to create a wide range of applications, including web and mobile applications, enterprise software, embedded systems, and more. This versatility provides developers with diverse career opportunities.
  3. Job Opportunities: According to industry reports, the demand for Java developers is projected to grow significantly in the coming years. The Bureau of Labor Statistics also predicts a 21% increase in employment for software developers, including Java developers, through 2028.
  4. Competitive Salaries: Java developers command attractive salaries due to the high demand and scarcity of experienced professionals. The average salary for a Java developer varies based on experience, location, and company size but typically ranges from $80,000 to $120,000 annually.

Top Java interview questions for 5 years experience

Here are some Java interview questions and answers for 5 years of experienced individuals: 

1. What is the difference between the == operator and the equals() method in Java?

In Java, the equals() and “==” operators can both be utilised to contrast objects and determine whether they are equal, but the key distinction between the two is that one is an operation and the other is an operator. While “==” is only used to compare objects, equals() can compare both primitives and objects.

2. Explain the concept of object-oriented programming (OOP) and its pillars.

 Object-oriented programming refers to a technique that is utilised by the majority of programming languages today to organise code and it will be mainly used for declaring classes and objects. Encapsulation, abstraction, inheritance, and polymorphism are the four OOPs pillars that are used to efficiently build software systems in object-oriented programming (OOP).These four pillars mainly used to build the foundation for writing scalable code.

3. What is the difference between abstract classes and interfaces in Java?

The extended keyword can be used to inherit from abstract classes. Only the implemented keyword can be used to implement an interface. Any type of member, such as private or public, can be included in an abstract class. All members of an interface must be public.

4. Can you explain the concept of method overloading and method overriding in Java?

Static polymorphism is a sort of method overloading. It is used to define many methods with an identical name but different parameters. When the main class and the sub-class share the same methods, particularly the parameters and signature, polymorphism is accomplished.

5. What is the purpose of the final keyword in Java? How does it affect classes, methods, and variables?

Java final keyword can be used to restrict access to a class, variable, or method. When a variable is initialized using the final keyword, its value cannot be changed.

A method cannot be overridden by subclasses if it is declared final. Additionally, when a class is declared final, other classes cannot inherit from or extend it.

To put it another way, other classes are unable to inherit from the final classes. The major goal of utilising a class that has been marked as final is to avoid subclassing. No class may inherit any features from a class that has been declared final.

A final class cannot be extended. You receive a build time error if you try it.

6. What are some of the common classes in Java?

Some of the common classes that are frequently used in Java are final, static, concrete, abstract,POJO and inner.

7. What are checked and unchecked exceptions in Java? Provide examples of each.

  • A runtime or undeclared exception occurs at runtime as opposed to a checked exception, which is detected at compile time.
  • While an unchecked exception doesn’t need to be handled, a checked exception has to be managed either by rethrowing or by using a try catch block.
  • A checked exception is typically an exception state within the code’s logic, whereas a runtime exception is an error in programming that is deadly and cannot be retrieved from.

Unchecked exception handling example: NullPointerException, ClassCastException, ArithmeticException.

Checked exception handling: ClassNotFoundException, SocketException, SQLException

8. How does garbage collection work in Java? Explain the different generations of the garbage collector.

Java programmes automatically manage memory using a process called garbage collection. Java programmes can be executed on a Java Virtual Machine, or JVM, by compiling to bytecode. Objects are formed on the heap, a section of memory reserved for the programme, when Java programmes are launched on the JVM. Some things will eventually become obsolete. To free up memory, the garbage collector discovers these useless objects and deletes them.

The managed heap is split into three generations—0, 1, and 2—to help the garbage collector function as efficiently as possible and manage long-lived or short-lived objects individually.

Learn More: Top 100 Java Interview Questions with Detailed Answers

9. What is the static keyword used for in Java? How does it affect variables and methods?

The static keyword in Java is mostly used for memory management. Variables, methods, blocks, and nested classes can all be utilized with it. It is a keyword used for distributing a variable or method across other classes. In general, static refers to a variable or method which remains the same for each instance of a class.

10. Can you explain the concept of multithreading in Java? How do you create and synchronize threads?

Java’s multithreading capability enables simultaneous execution of two or more programme components for maximum CPU efficiency.When many threads attempt to use an item at the same time, thread synchronization is the mechanism that limits access to the object to only one thread. The “synchronized” keyword or modifier has to be used to achieve thread synchronization.

11. What is the purpose of the synchronized keyword? How does it ensure thread safety?

In order to ensure that only one thread is running the synchronized code, the Java  synchronized keyword employs locks on objects or classes internally.

12. How does Java handle memory management? Explain the difference between stack and heap memory.

Memory management in Java refers to the process of allocating and freeing up space for objects. Java automatically manages memory. The garbage collector is an autonomous memory management technique used by Java. As a result, our programme does not need to include memory management logic.

JVM’s memory space is separated into two sections: Stack space and Heap space. Local variables and the execution order of methods are often stored on the stack space.

While heap memory use dynamic allocation to allocate and deallocate memory blocks, stack consistently kept blocks in LIFO order. 

Items with a very limited lifespan, such as local variables and object reference variables, are stored in stack memory. For the storage of objects and JRE classes, heap memory is allocated.

Also Read: Top Core Java Interview Questions and Answers

13. What is the Java Virtual Machine (JVM)? How does it execute Java programs?

Java Virtual Machine is an abstract machine and execution of java bytecode occurs during the runtime environment.

The Java Virtual Machine (JVM) executes the bytecode created by the Java compiler from the source code. The JVM receives the loaded bytecode, interprets it, and then runs the programme. 

14. What are the different access modifiers in Java (e.g., public, private, protected, default)? Explain their visibility and usage.

Modifier Visibility
Default Declarations can be visible only within the package (package private)
Private Declarations can be visible within the class only
Protected Declarations are visible within the subclasses or packages
Public Declarations can be visible everywhere

15. How do you handle exceptions in Java? What are the best practices for exception handling?

Reacting to undesirable or unexpected events that occur while a computer programme is running is known as exception handling. Without this process, exceptions would interfere with a program’s regular functioning and cause it to crash. 

Here are some best practices to be followed while doing exception handling and they are:

  • Try block encloses code can helps to throw an exception
  • Using one or more catch code blocks can handle exception 
  • Block which gets executed after try block can be executed to carry out exception handling process

16. Can you explain the concept of serialization in Java? How do you serialize and deserialize objects?

The idea of encoding an object’s state to a byte stream is known as serialisation in Java. 

Read More: If you want to uplift your career from basic level to next level, try our Top Java Developer Interview Questions

When an object is serialised, its state is transformed into a byte stream, which can then be transformed back into a duplicate of the original object. If the class or one of its super classes supports anyone of the Java IO interfaces, then the Java object becomes serializable. 

We use the writeObject() function of the ObjectOutputStream class to serialise the object, and the readObject() function of the ObjectInputStream class to deserialize it. 

17. What is the difference between a StringBuilder and a StringBuffer in Java? When would you use each?

StringBuilder  StringBuffer 
StringBuffer can be synchronized i.e. thread will be safe.  StringBuilder is non-synchronized i.e. thread is not safe. 
StringBuffer is less efficient than StringBuilder  StringBuilder is more efficient than StringBuffer
StringBuffer released in Java 1.0 StringBuilder released in Java 1.5

StringBuilder class is required when you want to alter a string without the usage of a new object. 

A string buffer does the same operation like String , but it can be modified. 

18. Explain the concept of polymorphism in Java. How does it relate to inheritance and method overriding?

When there are numerous classes that are connected to one another by inheritance, a phenomenon known as polymorphism which means “many forms”—occurs. We can inherit methods and attributes from a different class through inheritance. These techniques are used by polymorphism to carry out various tasks.

19. Can you explain the concept of Java annotations? Provide examples of built-in annotations and their usage.

Java annotations represent metadata for the software source code. Although they are not a part of the programme itself, they give the compiler more information about the programme. These annotations have no impact on how the compiled programme runs. Let’s look at a example: @Override annotation.

The @Override annotation shows that the indicated method overrides the superclass method by having the identical method name, return type, and argument list.

20. How do you handle concurrent modification exceptions when working with collections in Java?

There are two fundamental approaches can be used for handling concurrent modification exception and they are:

When an iterator is looping across a collection, do not alter it. If you can’t prevent the iteration from changing the underlying collection, make a copy of the desired data structure and iterate over the copy instead.

Conclusion

Hope this article comes up with Java interview questions for 5 years experienced individuals or more to get well prepared for the interview phase. Preparing for a Java interview with 5 years of experience requires a solid understanding of fundamental concepts, practical experience with Java development, and knowledge of more advanced topics. 

Apart from technical questions, interviewers might also evaluate your problem-solving skills, teamwork abilities, and your approach to software development. Be prepared to discuss your past projects, challenges you faced, and solutions you implemented.

If you have any questions on this blog, please feel free to comment us!

About Dharmendra Digari

Dharmendra Digari carries years of experience as a product manager. He pursued his MBA, which honed his skills of seeing products differently than others perceive. He specialises in products from the information technology and services domain, with a proven history of expertise. His skills include AWS, Google Cloud Platform, Customer Relationship Management, IT Business Analysis and Customer Service Operations. He has specifically helped many companies in the e-commerce domain establish themselves with refined and well-developed products, carving a niche for themselves.

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