Updated Java interview questions 2022

1. What is the current version of java?

Topic: core-java

Answer:

Java 19

Java has the following version and history

Java 8

Java 11

Java 17

Java 18

Java 19

Complexity: beginner

2. What is the difference between interface and abstract class in Java?

Topic: core-java

Answer:

Complexity: beginner

3. What is method overriding and method overloading in Java

Topic: core-java

Answer:

Complexity: beginner

4. What is the Exception handling mechanism available in Java

Topic: core-java

Answer:

Complexity: beginner

5. What is meant by the OOPS Concepts?

Topic: core-java

Answer:

Complexity: beginner

6. What is meant by inheritance

Topic: core-java

Answer:

Complexity: beginner

7. What is a final class?

Topic: core-java

Answer:

Complexity: beginner

8. Can we inherit a final method from super class in Java

Topic: core-java

Answer:

Complexity: beginner

9. How to prevent the subclass getting inherited the superclass methods?

Topic: core-java

Answer:

Complexity: beginner

10. What is a UML diagram? Which one are you familiar with?

Topic: core-java

Answer:

Complexity: beginner

11. What are the new features provided by Java8?

Topic: core-java

Answer:

Complexity: beginner

12. Do you know collection classes in Java?

Topic: core-java

Answer:

Collection is the way to store multiple items in a single unit.

Complexity: beginner

13. What is difference between String Buffer and String Builder?

Topic: core-java

Answer:

Complexity: beginner

14. What are the collection libraries you are familiar with?

Topic: core-java

Answer:

Complexity: beginner

15. How to print contents of an Array List using Stream API?

Topic: programming

Answer:

We can print the contents of an ArrayList, See the code below

import java.io.*;
import java.util.*;
public class TestClass {
    public static void main(String[] args) {
        ArrayList<String> arrList= new ArrayList();
        arrList.add("India");
        arrList.add("Brazil");
        arrList.add("Peru");
        arrList.stream().forEach(System.out::println);
    }
}

Complexity: beginner

16. How to retrieve the contents of an Array List?

Topic: core-java

Answer:

Complexity: beginner

17. What is a HashMap?

Topic: core-java

Answer:

Complexity: beginner

18. What is the superclass of any class?

Topic: oops-concepts

Answer:

Object class is the superclass of all classes in Java.

Complexity: beginner

19. What are the methods available in the Object class?

Topic: core-java

Answer:

Complexity: beginner

20. How to retrieve a value from a HashMap?

Topic: core-java

Answer:

Complexity: beginner

21. What is meant by design pattern?

Topic: core-java

Answer:

Complexity: beginner

22. What is a Singleton Design Pattern?

Topic: core-java

Answer:

Complexity: beginner

23. What are the design patterns you are familiar with?

Topic: core-java

Answer:

Complexity: beginner

24. What is meant by Null Pointer Exception? How you avoid them?

Topic: core-java

Answer:

Complexity: beginner

25. How can you avoid unchecked exceptions?

Topic: core-java

Answer:

Complexity: beginner

26. Can you write a code to print the content of the Array list using steam API

Topic: core-java

Answer:

Complexity: beginner

27. Can you write a code to declare a HashMap and print its contents?

Topic: core-java

Answer:

Complexity: beginner

28. How do you inherit class A to class B, which keyword do you use?

Topic: core-java

Answer:

Complexity: beginner

29. What are the differences between Checked Exception Vs Unchecked Exception?

Topic: exception-handling

Answer:

Complexity: beginner

30. Can you write a code to declare an array list and print its contents?

Topic: programming

Answer:

Complexity: beginner

31. What is the difference between List and Set in Java

Topic: collection

Answer:

Complexity: beginner

32. Which one is faster List or Set

Topic: collection

Answer:

Complexity: intermediate

33. How to sort an array list with stream.sorted() in Java 8

Topic: collection

Answer:

In this post, we will discuss how to sort a ArrayList with steam API. We consider normal List<String> and List of the custom object in the example.

Complexity: intermediate

34. How to sort an array list of custom object with stream.sorted() in Java 8

Topic: collection

Answer:

Sorting using stream required very less coding. see the sample below

List<CompanyTableEntity> companyTableEntities =      companies.stream().sorted(Comparator.comparing(CompanyTableEntity::getName)).collect(Collectors.toList());

If you watch closely the sorted method in the stream API does the task, and The stream is running on the first list. There is a comparator defined inside the sorted method that defines on what basis the Company object needs to sort. Once sorted it is collected as a list and passed back to a new list

Complexity: intermediate