How To Interview Java Developers

Q 42 Why Are Generics Used In Java Programming

Compile-time type safety is provided by using generics. Compile-time type safety allows users to catch unnecessary invalid types at compile time. Generic methods and classes help programmers specify a single method declaration, a set of related methods, or related types with an available class declaration.

Describe The Use Of The Finalize Method

This method is called by the Java garbage collector when there are no references to an object. Actually, the finalize method of the Object class doesnt do anything, but allows to override it to do clean up tasks like breaking I/O connections or dispose of system resources. Using the finalize method is a good indication of efficient programming and clean code.

Q11 What Is Encapsulation In Java

Encapsulation is a mechanism where you bind your data and code together as a single unit. Here, the data is hidden from the outer world and can be accessed only via current class methods. This helps in protecting the data from any unnecessary modification. We can achieve encapsulation in Java by:

• Providing public setter and getter methods to modify and view the values of the variables.

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About Java Certification Course

This Java certification course online is designed for students and professionals who want to be Java Developer. This 42-hour Java training will cover core and advanced Java concepts like Java Array, Collections, Database connectivity, Threads, Exception Handling, JSP, Servlets, XML handling, etc. You will also learn various Java frameworks like Hibernate and Spring.

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What Is The Is

IS-A relationship is another name for inheritance. When we inherit the base class from the derived class, then it forms a relationship between the classes. So that relationship is termed an IS-A Relationship.

Example – Consider a Television . Now another Smart TV that is inherited from television class. So we can say that the Smart iv is also a TV. Because CRT TV things can also be done in the Smart TV.

So here IS-A Relationship formed. .

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Q12 What Are The Important Methods Of Java Exception Class

Exception and all of its subclasses doesnt provide any specific methods and all of the methods are defined in the base class Throwable.

How Do You Remove Leading And Trailing Spaces From A String In Java

The String class contains two methods to remove leading and trailing whitespaces: trim and strip. The strip method was added to the String class in Java 11. The strip method uses the Character.isWhitespace method to check if the character is a whitespace. This method uses Unicode code points, while the trim method identifies any character with a codepoint value less than or equal to U+0020 as a whitespace character.

The strip method is the recommended way to remove whitespaces because it uses the Unicode standard. The following example code shows how to use the strip method to remove whitespaces:

String s ="  abc  def\t" s = s.strip System.out.println 

Because String is immutable, you have to assign the strip output to the string.

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Java Engineer Hiring Process

Companies are giving extra effort to optimize the hiring process to find the perfect fit. Working with different companies, we witnessed the best and the worst practices when it comes to the selection process. Typically, the steps would be:

Prescreening

Prescreening is a video or phone call to collect the necessary information about the candidates background. A recruiter may ask you about education, previous experience, motivation to change job, and salary expectations. This step is also essential to candidates. By asking the right questions, you can decide if this opportunity is right for you. It will save you time if you learn something about the company or the project thats not on your plan.

On-site interview

Once you passed the prescreening, the company wants to learn more about your technical and soft skills. The most common practice is to combine technical and HR interviews into one day, saving both your and the companys time. If this is the case, prepare for both sides of the coin. Having a strong technical background is essential, but companies want to make sure that you can fit with the rest of the team well. Communication is a vital part of any software engineering team. You should pay attention to demonstrate your willingness to listen and provide feedback accurately during the whole process. Just as on any job interview, you will go through a few phases.

Technical interview

Final interview

The Offer

How Do You Check Whether A String Is A Palindrome In Java

A palindrome string is the same string backwards or forwards. To check for a palindrome, you can reverse the input string and check if the result is equal to the input. The following example code shows how to use the String charAt method to check for palindrome strings:

booleancheckPalindromeString}return result }

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Q 57 What Is Jca In Java

Java Cryptography Architecture gives a platform and provides architecture and application programming interfaces that enable decryption and encryption.

Developers use Java Cryptography Architecture to combine the application with the security applications. Java Cryptography Architecture helps in implementing third party security rules and regulations.

Java Cryptography Architecture uses the hash table, encryption message digest, etc. to implement the security.

Q45 What Is Collection Class In Java List Down Its Methods And Interfaces

In Java, the collection is a framework that acts as an architecture for storing and manipulating a group of objects. Using Collections you can perform various tasks like searching, sorting, insertion, manipulation, deletion, etc. Java collection framework includes the following:

The below image shows the complete hierarchy of the Java Collection.

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Q7 Can You Explain The Java Thread Lifecycle

The java thread lifecycle has the following states-

New-

When a thread is created, and before the program starts the thread, it is in the new state. It is also referred to as a born thread.

Runnable

When a thread is started, it is in the Runnable state. In this state, the thread is executing its task.

Waiting

Sometimes, a thread goes to the waiting state, where it remains idle because another thread is executing. When the other thread has finished, the waiting thread again comes into the running state.

Timed Waiting

In timed waiting, the thread goes to waiting state. But, it remains in waiting state for only a specified interval of time after which it starts executing.It remains waiting either till the time interval ends or till the other thread has finished.

Terminated

A thread is said to be in this state once it terminates. It may be because the thread has completed its task or due to any other reason.

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Which Developer Methodologies Are They Familiar With

The most significant change in software development has been the shift in methodologies. Updates to methodologies can enable developers to create applications faster, but they can also lead to delays if your developers arent up to speed with the latest practices.

There are many methodologies available for a business to use, many of which can be combined, so asking a developer about their experience during an interview is a big telling point in whether theyre right for you.

Currently, the most favoured methodology is Agile, which promotes cross-collaboration between everyone involved in the development process. It also encourages businesses to develop in sprints, that, once completed, will enable the work to be tested and evaluated before deployment.

Discovering a developer who has this expertise can help you uncover a developer who matches the job description. But to find out their experience of Agile, Waterfall or Scrum, youll need to ask the questions that focus on their experience.

Agile isnt the only methodology commonly used today, however. Waterfall development, combined with scrum and the use of regular stand-ups, is now becoming more popular, as it allows for quick and controlled app production.

Having a developer who is experienced in more than one primary methodology can be beneficial, so ask a developer to explain their knowledge of both.

Salary Based On Company

Here is a list of top companies and their average salary for the role of a Java Developer in India.

Senior Java developers are experienced in writing code, dealing with bad code, and knowing how to fix the issues up. They are aware of the functions and tasks an application performs and mentors junior developers and trainees. They can debug complicated problems and provide the fastest and efficient way possible.

They possess strong communication skills as they should not just offer the best solution but also convince a customer why the solution is best. To reach this position, one must have 5-10 years of experience.

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What Do You Understand By An Instance Variable And A Local Variable

Instance variables are those variables that are accessible by all the methods in the class. They are declared outside the methods and inside the class. These variables describe the properties of an object and remain bound to it at any cost.

All the objects of the class will have their copy of the variables for utilization. If any modification is done on these variables, then only that instance will be impacted by it, and all other class instances continue to remain unaffected.

Example:

classAthlete

Local variables are those variables present within a block, function, or constructor and can be accessed only inside them. The utilization of the variable is restricted to the block scope. Whenever a local variable is declared inside a method, the other class methods dont have any knowledge about the local variable.

Example:

publicvoidathlete

Can Java Be Said To Be The Complete Object

It is not wrong if we claim that java is the complete object-oriented programming language. Because Everything in Java is under the classes. And we can access that by creating the objects.

But also if we say that java is not a completely object-oriented programming language because it has the support of primitive data types like int, float, char, boolean, double, etc.

Now for the question: Is java a completely object-oriented programming language? We can say that – Java is not a pure object-oriented programming language, because it has direct access to primitive data types. And these primitive data types don’t directly belong to the Integer classes.

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What Platforms Does The Java Programming Language Support

This question tests your basic knowledge of Java. The interviewer may use it to determine which environments you’ve used for Java development. To answer this question, you can give a simple list of supported platforms that demonstrate your knowledge of the types available to Java users.

Example: “Java runs on several platforms. Some of these are Windows, macOS and popular instances of Linux/UNIX. The choice of a running environment may depend on the programming task. For instance, UNIX environments may be suitable when programming UNIX applications.”

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How Do You Check If A List Of Integers Contains Only Odd Numbers In Java

You can use a for loop and check whether each element is odd:

publicstaticbooleanonlyOddNumbersreturntrue }

If the list is large, you can use parallel stream for faster processing, as shown in the following example code:

publicstaticbooleanonlyOddNumbers

To learn more about the math behind determining if an integer is odd, refer to the Modulo operation on Wikipedia.

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How Do You Illustrate A Try Catch Example In Java

The following example code shows an example of try-catch:

trycatch

From Java 7 onwards, you can also catch multiple exceptions in a single catch block, as shown in the following example. Itâs useful when you have the same code in all the catch blocks.

publicstaticvoidfoothrowsIllegalArgumentException,NullPointerExceptionpublicstaticvoidmaincatch}

What Is Method Overriding In Java

Method overriding in Java stands for a feature that allows a subclass or child class to complete a specific implementation of a method that has been done by one of its superclasses or parent classes. One of the benefits of this method is that it assists in defining a specific class type behavior so that a subclass can use a parent class method based on its type.

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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 itâs helpful in Java.

Example: âAn 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 objectâs state to facilitate communication between objects.â

Q36 What Is Java String Pool

Java String pool refers to a collection of Strings which are stored in heap memory. In this, whenever a new object is created, String pool first checks whether the object is already present in the pool or not. If it is present, then the same reference is returned to the variable else new object will be created in the String pool and the respective reference will be returned.

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Do You Use Github Or Another Vcs Tool

A Version Control System or VCS records changes to files that you can retrieve at a later date.

Most Java developers use a VCS to store all changes made to their source code. They can revert to working code if the current source breaks functionality. That could include reverting an entire project to just one page of code.

An online distributed VCS offers an even bigger advantage: code branching.

Other developers can mirror or clone the existing code then branch off on their own to develop it. Many popular open-source apps get developed this way. Changes get combined into the main branch and everyone benefits.

VCS is all about safeguarding code and promoting development in a team.

A candidates response should demonstrate these concepts. It should outline how versioning control works and why its important.

As Github powers the majority of VCS, the candidate should underline the platforms importance.

Preferably, they will have experience in Github versioning control. That includes setting up repositories and checking in/out code. Command-line experience is a bonus but GUI is fine too.

Key Java Interview Questions For Entry Level Java Junior Developers

Many managers avoid entry-level java developers because they think they dont have time to teach them things. Or they are scared that juniors will screw things. Yet, entry-level employees have all the new ideas, and information seniors sometimes are lacking. If you have an upcoming interview with an entry-level Java developer, you should know that identifying talented ones is not easy.

Thats why we made a list with the 8 best junior Java developer interview questions:

1. How does Java achieve platform independence?

Java platform independency means that the Java program can run on any platform or operating system without suffering any changes. This is possible because of the bytecode.

When the Java program runs in a particular machine it is sent to the Java compiler. The result of this is the conversion of the original code into an intermediate code called bytecode. This bytecode is sent to Java Virtual Machine which resides in the RAM of any operating system. JVM recognizes the platform and converts the bytecodes into native machine code.

2. What are the various access specifiers for Java classes?

Access specifiers are the keywords used before a class name that defines the access scope.

There are four types of access specifiers:

3. What is the Difference Between ArrayList and HashSet in Java?

The following ones are the main differences between ArrayList and HashSet:

Implementation

HashSet set=new HashSet  

4. What is a Java ClassLoader?

1.For Loops

2.While Loops

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What Are The Different Types Of Thread Priorities In Java And What Is The Default Priority Of A Thread Assigned By Jvm

There are a total of 3 different types of priority available in Java.

MIN_PRIORITY: It has an integer value assigned with 1.MAX_PRIORITY: It has an integer value assigned with 10.NORM_PRIORITY: It has an integer value assigned with 5.

In Java, Thread with MAX_PRIORITY gets the first chance to execute. But the default priority for any thread is NORM_PRIORITY assigned by JVM.