Basic Interview Questions in Java for Freshers with Answer

Here are some basic interview questions and answers for Java:

Q: What is JavaScript and what is it used for?

Ans: JavaScript is a programming language that is mainly used for creating dynamic and interactive web pages. It allows for the manipulation of HTML and CSS, and can also be used for creating web and server-side applications.

Q: What is the difference between let and var in JavaScript?

Ans: var is function scoped, while let is block scoped. let also has a temporal dead zone (TDZ) which means a variable declared with let cannot be accessed before it is declared.

Q: What is hoisting in JavaScript?

Ans: Hoisting is a behavior in JavaScript where variables and function declarations are moved to the top of their scope, regardless of where they are declared.

Q: What is the event loop in JavaScript?

Ans: The event loop is a mechanism that allows JavaScript to perform non-blocking I/O operations by continuously checking the message queue and executing code for the next task.

Q: What is a closure in JavaScript?

Ans: A closure is a function that has access to the variables in its parent scope, even after the parent function has returned.

Q:  What is a callback function in JavaScript?

Ans: A callback function is a function passed as an argument to another function, which is then invoked inside the outer function.

Q: What is the difference between an object and a class in Java?

Ans: An object is an instance of a class, while a class is a blueprint or template for creating objects.

Q: What is the difference between a constructor and a method in Java?

Ans: A constructor is a special type of method that is used to initialize an object when it is created, while a method is a function that performs a specific task and may or may not return a value.

Q: What is the difference between a static method and an instance method in Java?

Ans: A static method belongs to a class and can be called without creating an object, while an instance method belongs to an object and can only be called on a specific instance of a class.

Q: What is the purpose of the main() method in Java?

Ans: The main() method is the entry point of a Java program and is where the program starts executing.

Q: What is the difference between the equals() method and the == operator in Java?

Ans: The equals() method is used to compare the contents of two objects, while the == operator is used to compare the memory addresses of two objects.

Q: What is the purpose of an interface in Java?

Ans: An interface is a collection of abstract methods that a class can implement. It is used to define a contract for the behavior of a class, but does not provide any implementation details.

Q: What is the difference between an Array List and a LinkedList in Java?

Ans: An ArrayList is backed by an array and provides constant-time performance for the basic operations (get and set), while a LinkedList is backed by a linked list and provides constant-time performance for insertion and deletion operations.

Q: What is the difference between synchronous and asynchronous code in JavaScript?

Ans: Synchronous code is executed in the order in which it is called, while asynchronous code is executed at a later time, independent of the main execution thread.

Q: What is the difference between a forEach loop and a for loop in JavaScript?

Ans: A forEach loop is used to iterate over an array and execute a callback function for each element, while a for loop is more general and can be used to iterate over arrays, as well as other types of data