How To Interview Java Developer

Q 2 List The Features Of The Java Programming Language

A few of the significant features of Java Programming Language are:

Easy: Java is a language that is considered easy to learn. One fundamental concept of OOP Java has a catch to understand.

Secured Feature: Java has a secured feature that helps develop a virus-free and tamper-free system for the users.

OOP: OOP stands for Object-Oriented Programming language. OOP signifies that, in Java, everything is considered an object.

Independent Platform: Java is not compiled into a platform-specific machine instead, it is compiled into platform-independent bytecode. This code is interpreted by the Virtual Machine on which the platform runs.

Full Stack Java Developer Course

Tips For Acing Java Developer Roles

You should know and understand basic concepts like loops, arrays, operators, and other basic functionality libraries. Also, focus on implementing OOPs concepts.

• Keep Practicing

After getting a hang of the basics, you can try learning Java EE aka advanced java. This includes technologies like Servlet, WebSocket, Java Server Faces, etc. for web specifications.

This is something that you can add to your resume to showcase your problem-solving and practical coding skills.

• Learn Specific Libraries/Tools

Most Java Development Companies use Spring frameworks such as Spring Boot, Spring MVC, and Spring Cloud for developing web applications. Hibernate is also a very popular framework for mapping a domain object-oriented model to a relational database and the Hibernate Query Language.

What Is Long Polling

Long polling is an effective method for creating a stable server connection without using the WebSocket or Server-Side Events protocols. It operates at the top of the conventional client-server model. Note that Node.js is using the same technique as the next development model.

In this method, the client sends the request and the server responds until the connexon is open as it contains new and unique information. As soon as the server responds, a request to the client can be submitted. When the data is available, the server will return a query. It functions when the client application stops and the server ends requests.

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What Do You Mean By Promise Also Explain Its States

A promise is an object that can be returned synchronously from an asynchronous function. It may be in the following three states:

• Fulfilled: If a promise called the onFulfilled method, a promise will be in fulfilled state.
• Rejected: If a promise called the onRejceted method, a promise will be in rejected state.
• Pending: If a promise is not yet fulfilled or rejected, a promise will be in pending state.

A promise will be settled if and only if it is not pending.

Can You Prove That A String Object In Java Is Immutable Programmatically

The following example code shows how to prove that a String object is immutable and the comments in the code explain each step:

String s1 ="Java" // "Java" String created in pool and reference assigned to s1String s2 = s1 //s2 also has the same reference to "Java" in the poolSystem.out.println // proof that s1 and s2 have the same references1 ="Python" //s1 value got changed above, so how String is immutable?//in the above case a new String "Python" got created in the pool//s1 is now referring to the new String in the pool //BUT, the original String "Java" is still unchanged and remains in the pool//s2 is still referring to the original String "Java" in the pool// proof that s1 and s2 have different referenceSystem.out.println System.out.println // prints "Java" supporting the fact that original String value is unchanged, hence String is immutable

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Q18 What Is A Constructor Overloading In Java

In Java, constructor overloading is a technique of adding any number of constructors to a class each having a different parameter list. The compiler uses the number of parameters and their types in the list to differentiate the overloaded constructors.

class Demopublic Demo}

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Why Is Java A Platform Independent Language

Java language was developed in such a way that it does not depend on any hardware or software due to the fact that the compiler compiles the code and then converts it to platform-independent byte code which can be run on multiple systems.

• The only condition to run that byte code is for the machine to have a runtime environment installed in it.

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How Do You Write An Interface With Default And Static Method

Java 8 introduced default and static methods in interfaces. This bridged the gap between interfaces and abstract classes. The following example code shows one way to write an interface with the default and static method:

publicinterfaceInterface1staticbooleanisNull}

Learn more about about default and static methods in interfaces in Java 8 interface changes.

What Motivated You To Become A Java Developer

Golden Technology had a vision over twenty years ago.

We wanted technology that was people-inspired. One that would conquer new horizons. We wanted to build a family of IT professionals that would develop the world.

You can follow in our footsteps by asking your potential employee what motivated them to become a Java developer.

If you see passion flowing as they talk then take notice. Programming isnt for everyone and some see it as a 9 to 5 job.

Those who understand that developing isnt just about code are worth their weight in gold. Software can change the world do they share that vision?

Candidates should also discuss other languages and expertise they possess.

Give extra credit for each coding language and experience developing with it. If theyve worked with Cloud technologies and modern infrastructures give bonus points.

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How Can You Find A String In A Text File In Java

The following example code shows how to use the Scanner class to read the file contents line by line and then use the String contains method to check if the string is present in the file:

booleanfindStringInFilethrowsFileNotFoundException}scanner.close returnfalse }

Note that the example code assumes that the string that youâre searching for in the file doesnât contain newline characters.

What Is Cors In Mvc And How It Works

CORS stands for Cross-Origin Resource Sharing. It is a W3C standard and HTTP-header-based mechanism. It permits a server to indicate any other origins instead of the requested one. In other words, it enables one website to access the resources of another website using JavaScript.

It supports secure cross-origin requests and transfers data between servers and browsers. Advanced browsers use CORS in APIs. It is flexible and safe in comparison to JSONP . It provides better web service integration.

While using the MVC to enable CORS, the same CORS service can be used but we cannot use the same CORS middleware. We can use a particular CORS for a particular action, for a particular controller, and globally for all controllers.

A pre-flight check is sent by the browser to the server which ensures that the server will permit the actual request or not. For example, invoking the URL through .

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Q14 What Is Composition In Java

Composition is again a specialized form of Aggregation and we can call this as a death relationship. It is a strong type of Aggregation. Child object does not have their lifecycle and if parent object deletes all child object will also be deleted. Lets take again an example of a relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different houses if we delete the house room will automatically delete.

Q15. What is a marker interface?

A Marker interface can be defined as the interface having no data member and member functions. In simpler terms, an empty interface is called the Marker interface. The most common examples of Marker interface in Java are Serializable, Cloneable etc. The marker interface can be declared as follows.

public interface Serializable

Q16. What is object cloning in Java?

What Is A Final Class

This question may test your understanding of different Java classes. Understanding a final class can allow you to decide when to use it. You can respond by explaining a final class in Java and how it’s useful.

Example: “The final keyword in java finalizes the implementation of classes and other variables. This finalization means the variables are unalterable. In a final class, a method the class implements is constant, meaning it ensures the behavior and implementation of the class are immutable.”

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What Distinguishes A Great Software Engineer From A Good One Do You Feel You Have Those Qualities

Well, you dont want to brag, but Just be honest, where are you when it comes to your skills, and where you want to be. Show a recruiter that you want to learn about the new technologies every day, that youre aware that the learning process never ends. Be positive about your knowledge, but aware of your lack of expertise. Applicants should showcase their enthusiasm for development and talk about any projects theyre working on outside of a job.

Q 68 Could You Provide Some Implementation Of A Dictionary Having A Large Number Of Words

The simplest implementation that can be given is that of a List wherein one can place ordered words and perform a Binary search. The other implementation with a better search performance is HashMap where the key is used as the first character of the word and the value as a LinkedList.

Up another level, there are HashMaps like:

hashmap {

a -> hashmap

b -> hashmap

z -> hashmap

Up to n levels where n is the average size of the word in the dictionary.

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What Variance Is Imposed On Generic Type Parameters How Much Control Does Java Give You Over This

Javas generic type parameters are invariant. This means for any distinct types A and B, G< A> is not a subtype or supertype of G< B> . As a real world example, List< String> is not a supertype or subtype of List< Object> . So even though String extends Object, both of the following assignments will fail to compile:

        List< String>  strings = Arrays.< Object> asList         List< Object>  objects = Arrays.< String> asList 

Java does give you some control over this in the form of use-site variance. On individual methods, we can use ? extends Type to create a covariant parameter. Heres an example:

        public double sum             return sum         }        List< Long>  longs = Arrays.asList         double sumOfLongs = sum 

Even though longs is a List< Long> and not List< Number> , it can be passed to sum.

Similarly, ? super Type lets a method parameter be contravariant. Consider a function with a callback parameter:

        public void forEachNumber 

forEachNumber allows Callback< Object> to be a subtype of Callback < Number> , which means any callback that handles a supertype of Number will do:

        forEachNumber         }) 

Note, however, that attempting to provide a callback that handles only Long will rightly fail:

        // fails to compile!        forEachNumber ) 

Liberal application of use-site variance can prevent many of the unsafe casts that often appear in Java code and is crucial when designing interfaces used by multiple developers.

        onShutdown ->  service.stop) 

Question : What Are Access Specifiers In Java

There are four access specifiers which the candidate should understand. There are the following qualifiers: public, private, protected and standard.

Public qualifiers allow access to any class or through any method . In contrast, private specifiers only allow access within the specified class itself. Protected ones open access that somehow correlates with the class – either from within the class, from a subclass, or simply from the same package. Finally, default denotes a standard area and allows access from only one package.

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Write A Java Program To Print A Fibonacci Sequence Using Recursion

A Fibonacci sequence is one in which each number is the sum of the two previous numbers. In this example, the sequence begins with 0 and 1. The following example code shows how to use a for loop to print a Fibonacci sequence:

publicclassPrintFibonacci}publicstaticvoidmain}

Output0, 1, 1, 2, 3, 5, 8, 13, 21, 34,

You can also use recursion to print a Fibonacci sequence, because the Fibonacci number is generated by adding the previous two numbers in the sequence:

F = F + F

The following example class shows how to use recursion to calculate a Fibonacci sequence that is 10 numbers long:

publicclassPrintFibonacciRecursivepublicstaticvoidmain}}

OutputA Fibonacci sequence of 10 numbers: 0 1 1 2 3 5 8 13 21 34

If You Find A Bug In A Complex System What Would You Do To Fix It

Any software developer can debug as one of his basic skills. But the right approach is to break down the problem rather than finding small errors in code snippets. If your answer contains the following key phrases, you will ace this question:

• Asking for help from other Java coders
• Breaking down the problem into smaller parts
• Checking the code for similar errors
• Expressing and testing assumptions
• Turn problems into learning experiences
• Using a measured, scientific approach
• Writing tests to ensure that the bug does not returns

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Which Software Development Process Are They Familiar With

When committing to the development of any piece of software, youll need to choose a Java developer who is not only familiar with your development methodology but can also navigate the process you follow.

Creating, testing and deploying any software will take time, and if one element is missing or behind schedule, itll mean delays or unfinished projects.

Finding out which development processes a candidate is familiar with should be a key part of the interview scenario. Most will only have used one during their career. By discovering whether they favour TDD or BDD early in the process, it will help you decide whether theyre the suit the current development style of your business.

The two common processes, BDD and TDD, work equally as well as the other, but your business will probably favour one. Youll need a developer who has previously worked with your chosen process in a practical environment.

Question a developer on whether they prefer to test, fix and then run a deployment, or alternatively, if they prefer to create, run and then fix a piece of software.

Q4 What Are The Differences Between Forward Method And Sendredirect Methods

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Can You Tell The Difference Between Equals Method And Equality Operator In Java

Note:

• In the cases where the equals method is not overridden in a class, then the class uses the default implementation of the equals method that is closest to the parent class.
• Object class is considered as the parent class of all the java classes. The implementation of the equals method in the Object class uses the == operator to compare two objects. This default implementation can be overridden as per the business logic.

Q1 What Is The Difference Between Error And Exception

An error is an irrecoverable condition occurring at runtime. Such as OutOfMemory error. These JVM errors you cannot repair them at runtime. Though error can be caught in the catch block but the execution of application will come to a halt and is not recoverable.

While exceptions are conditions that occur because of bad input or human error etc. e.g. FileNotFoundException will be thrown if the specified file does not exist. Or a NullPointerException will take place if you try using a null reference. In most of the cases it is possible to recover from an exception (probably by giving the user feedback for entering proper values etc.

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Top 10 Java Developer Interview Questions

Are you struggling to find a good Java developer? Worse yet, have you hired Java developers who ended up being a poor fit? Maybe you need to step up your interview process. We curated a list of Java developer interview questions that can help you find the best developers for your company.

The resume is an important item in job applications. If you are hiring a tech professional, the first thing you would want to look at is their resume. There youll find their claimed skills, work experience, educational background, and others. However, this document is not everything.

During the interview, the hiring manager asks questions that can help them gain insight into the candidates professional and practical experience, accomplishments, and qualifications. Furthermore, this highlights the importance of a well-crafted list of interview questions.

What Is An Object In Java

An object is a standard Java component that has several uses. The hiring manager may use this question to test your familiarity with object-oriented programming. You can respond by explaining what an object is and how it’s helpful in Java.

Example: “An object in Java is a standard runtime entity. It has a state, which is present in the object fields and a defined behavior. Methods work with the object’s state to facilitate communication between objects.”

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