Top 20 Interview Questions And Answers On Java For Freshers

Top 20 Interview Questions And Answers On Java For Freshers

1. What is Java?
Java is a high-level, object-oriented programming language developed by Sun Microsystems (now owned by Oracle Corporation).

2. What are the features of Java?
Java has several features, including platform independence, object-oriented design, simple and familiar syntax, robust security, and large community support.

3. What is the difference between Java and C++?
Java and C++ are both object-oriented programming languages, but Java is platform-independent, while C++ is platform-dependent. Java also has automatic memory management through its garbage collector.

4. What is the syntax for declaring variables in Java?
In Java, variables are declared using the syntax “type name = value;”.

5. What is the difference between “==” and “.equals()” in Java?
In Java, “==” checks for reference equality (i.e., whether two objects point to the same memory location), while “.equals()” checks for value equality (i.e., whether two objects have the same value).

6. Can you explain the concept of inheritance in Java?
Inheritance is a mechanism in Java where one class can inherit the properties and behavior of another class. The child class inherits all the fields and methods of the parent class.

7. What is polymorphism in Java, and how is it achieved?
Polymorphism is the ability of an object to take on multiple forms. In Java, polymorphism is achieved through method overriding and method overloading.

Java interview questions

8. Can you describe the difference between static and dynamic binding in Java?
Static binding occurs at compile-time, while dynamic binding occurs at runtime. Static binding is used for private and static methods, while dynamic binding is used for non-private and non-static methods.

9. What is the purpose of the “this” keyword in Java?
The “this” keyword in Java is used to refer to the current object of the class.

10. Can you explain the concept of encapsulation in Java?
Encapsulation is the concept of hiding the implementation details of an object from the outside world and only exposing the necessary information through public methods.

11. What is the difference between abstract classes and interfaces in Java?
Abstract classes can have both abstract and concrete methods, while interfaces can only have abstract methods. Abstract classes can also have state, while interfaces cannot.

12. Can you explain the concept of multithreading in Java?
Multithreading is the ability of a program to execute multiple threads or flows of execution concurrently.

13. How do you synchronize threads in Java?
Threads can be synchronized using the “synchronized” keyword in Java.

14. What is the purpose of the “wait()” and “notify()” methods in Java?
The “wait()” method is used to make a thread wait until it is notified, while the “notify()” method is used to notify a waiting thread.

15. Can you explain the concept of Java Collections Framework?
The Java Collections Framework is a set of classes and interfaces that provide a unified architecture for representing and manipulating collections.

 

Top 20 Interview Questions And Answers On Java

16. What is the difference between ArrayList and LinkedList in Java?
ArrayList is a resizable-array implementation of the List interface, while LinkedList is a doubly-linked list implementation of the List interface.

17. Can you describe the concept of HashMap and its implementation in Java?
HashMap is a hash table implementation of the Map interface. It stores key-value pairs in a way that allows for efficient lookup, insertion, and deletion.

18. What is the purpose of the “hashCode()” and “equals()” methods in Java?
The “hashCode()” method is used to generate a hash code for an object, while the “equals()” method is used to compare two objects for equality.

19. Can you explain the concept of Java Generics?
Java Generics is a feature that allows for the creation of reusable code. It enables types (classes and interfaces) to be parameters when defining classes, interfaces and methods.

20. Can you describe the concept of Java Lambda Expressions?
Java Lambda Expressions are a concise way to represent a function or method. They consist of a set of parameters, a lambda operator (->), and a body.

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