Top 50 Java Interview Questions for Beginners and Junior Developers by javinpaul

It also reduces the number of times our OS needs to interact with the network or the disk. Buffering allows programs to write a big amount of data instead of writing it in small chunks. This also reduces the overhead of accessing the network or the disk. Java brings various Streams with its I/O package that helps the user to perform all the input-output operations.

The index of the first element is coming 0, and the last element index is coming 4, which is the size of the array minus 1. In this code, we pass the value of num to the changeValue() method. However, when we change the value of x inside the method, it does not affect the value of num outside the method. This is because Java passes a copy of the value of num, not the actual object. This means that when we pass an object to a method, a copy of the reference to that object is passed, not the actual object. The main difference between a final method and an abstract method in Java is that a final method cannot be overridden in a subclass, while an abstract method must be overridden in a subclass.

What will happen if we declare don’t declare the main as static?

They are keen to know if you can troubleshoot potential issues and leverage the benefits of multithreading to enhance user experience. As a lead Java developer, you’ll be expected to understand the inner workings of applications and be able to identify and troubleshoot any issues that arise. Knowing which tools to use to monitor performance and identify potential issues is key to successful development and maintaining good user experience. This question will give the interviewer an idea of your technical skills and understanding of the Java ecosystem.

  • The best way to answer this question is by providing examples of how you have used OOP concepts in past projects.
  • Additionally, discuss any strategies you have for ensuring that all code is properly documented and reviewed before being committed.
  • This question is important for lead developers because it shows that you understand the importance of writing code that is maintainable and can be modified or extended as needed.
  • Refactoring code can lead to better performance, fewer bugs, and easier collaboration with other developers.

Calling the `binarySearch` function triggers the `binarySearchRecursive` function. The `binarySearchRecursive` function executes the binary search algorithm through the utilization of recursion. Write a Java program to rotate arrays 90 degrees clockwise by taking matrices from user input. In case you attended any Java interview java 7 certifications recently, or have additional questions beyond what we covered, we encourage you to post them in our Java community questions. While it might seem like this question is about the order of execution of the mathematical operators, the question is really about noticing that the main method wasn’t declared static.

ii). finally

A jagged Array in Java is just a two-dimensional array in which each row of the array can have a different length. Since all the rows in a 2-d Array have the same length but a jagged array allows more flexibility in the size of each row. This feature is very useful in conditions where the data has varying lengths or when memory usage needs to be optimized. Both int array[] and int[] array are used to declare an array of integers in java. The only difference between them is on their syntax no functionality difference is present between them.

It’s crucial to log meaningful messages and include relevant information like class name or method where the issue occurred. Additionally, I leverage automated testing tools and continuous integration systems to catch bugs early and ensure the code works as expected across different environments. I also make use of comments to explain complex parts of the code, which aids in understanding during code reviews or future modifications. Then, provide specific examples of projects that demonstrate how you used Java in different ways.

Disadvantages of Arrays are:

A FailFast iterator is an iterator that throws a ConcurrentModificationException if it detects that the underlying collection has been modified while the iterator is being used. This is the default behavior of iterators in the Java Collections Framework. Implemented frequently in the API by Calendar, Wrapper classes, Date, and String. The logic of sorting must be in the same class whose object you are going to sort. The Iterator can traverse both legacies as well as non-legacy elements.

  • A Java developer should have a strong understanding of core Java concepts such as object-oriented programming, data types, control structures, and exception handling.
  • I have also shared some useful resources for further learning and improvement like The Complete Java MasterClass to brush up and fill gaps in your Java skills.
  • C++ is a good choice for developing high-performance applications that require direct access to the operating system.
  • Instance variables are initialized automatically by default values if not initialized explicitly, while local variables must be initialized explicitly before they can be used.
  • ResultSet returned is never null even if there are no records matching the query.
  • Are you learning Java and looking for exercises to test your new skills?
  • FileInputStream in Java is used to read data from a file as a stream of bytes.

If the function of the subclass depends on the superclass’s action, it suddenly becomes vulnerable. Sub-class functionality may be broken without any alteration on the part of the super-class when its behaviour changes. The first addAll() method accepts a single argument of type Collection, which is the collection of elements to be added to the list. The add() and addAll() methods      are the main methods at the List interface. The add() method is used to add an element to the list, while the addAll() method is used to add a collection of elements to the list.