Saturday, June 15, 2024

How To Prepare For Java Developer Interview

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Topics To Prepare For Full Stack Developer Interview

JAVA DEVELOPER Interview Questions And Answers! (JAVA Interview Questions, TIPS and ANSWERS!)

Irrespective of whether the job role is front-end framework intrinsic or backend, you should be well-versed with the basics. Topics you must prepare for include:


  • Data Structures
  • Character Encoding
  • In addition to this, knowing about the company, the job role, what the organization expects from you is an integral part of your stack developer interview preparation.

    What Are Static Initializers And When Would You Use Them

    A static initializer gives you the opportunity to run code during the initial loading of a class and it guarantees that this code will only run once and will finish running before your class can be accessed in any way.

    They are useful for performing initialization of complex static objects or to register a type with a static registry, as JDBC drivers do.

    Suppose you want to create a static, immutable Map containing some feature flags. Java doesnt have a good one-liner for initializing maps, so you can use static initializers instead:

            public static final Map< String, Boolean>  FEATURE_FLAGS         static 

    Within the same class, you can repeat this pattern of declaring a static field and immediately initializing it, since multiple static initializers are allowed.

    Other Intermediate Interview Questions For Java Developers

    Be sure you are well-versed and able to speak about multithreading, as its one of Javas most important features.

    Here are a few Java multithreading questions you might be asked:

    • How does multithreading work?
    • How to implement a thread in Java?
    • How to create daemon threads?
    • What is thread starvation?
    • What is the ExecutorService interface and how does it work?

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    Prepare For Your Next Java Interview With Interview Kickstart

    Itâs time to crack your next Java interview! Register for IKâs webinar today to learn how to take advantage of exclusive interview preparation courses and mock interviews with experts.

    Interview Kickstart has helped over 9,000 engineers land coveted offers from FAANG and tier-1 companies. Our instructors are technical leads and hiring managers at FAANG and know what it takes to crack Java interviews. Talk to our career counselors, or register for our webinar to learn more!

    Why Is Java A Platform Independent Language

    25 Java Developer Interview Questions &  Answers

    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.

    Also Check: Prepare For System Design Interview

    What Are The Different Ways Of Threads Usage

    • We can define and implement a thread in java using two ways:
    • Extending the Thread class
    classInterviewBitThreadExampleextendsThread  publicstaticvoidmain  }
    • Implementing the Runnable interface
    classInterviewBitThreadExampleimplementsRunnable  publicstaticvoidmain  }
    • Implementing a thread using the method of Runnable interface is more preferred and advantageous as Java does not have support for multiple inheritances of classes.
    • start method is used for creating a separate call stack for the thread execution. Once the call stack is created, JVM calls the run method for executing the thread in that call stack.

    Prepare For Specific Roles And Companies

    All interviews vary! In addition to studying industry-standard interview questions, you should tailor your interview preparation for your unique circumstances:

    • The level of the role: Expectations differ based on the level of the role youre applying to. Its difficult to provide a template, since every company is different, but a ballpark of the topics you could expect based on your level of experience include:
    • Java interview questions for junior developers will assess your general programming knowledge, OOP knowledge, and your understanding of Java basics.
    • Java interview questions for experienced developers are more likely to expect your knowledge of multithreading, concurrency, JVM internals, and Java collections.
  • The individual job description: This is the most important aspect to consider. Your job description gives you a rubric for all the qualifications your interviewers hope to see in you. You should prepare to highlight and justify the qualifications you meet. If there are qualifications you cant meet, dont sweat it. The deal-breaker qualifications are already addressed during the phone screening.
  • The company you apply for: Each company conducts interviews differently. Spend some time on forums and Glassdoor to explore what others have said about interviewing with the company. If youre interviewing at a top tech company such as FAANG, youll be able to find many company-specific interview guides, such as Netflix coding interview guides and .
  • Don’t Miss: Top 10 Behavioral Questions

    What Are The Differences Between Jvm Jre And Jdk In Java

    Java Virtual Machine
    Definition JDK is a complete software development kit for developing Java applications. It comprises JRE, JavaDoc, compiler, debuggers, etc. JRE is a software package providing Java class libraries, JVM and all the required components to run the Java applications. JVM is a platform-dependent, abstract machine comprising of 3 specifications – document describing the JVM implementation requirements, computer program meeting the JVM requirements and instance object for executing the Java byte code and provide the runtime environment for execution.
    Main Purpose JDK is mainly used for code development and execution. JRE is mainly used for environment creation to execute the code. JVM provides specifications for all the implementations to JRE.
    Tools provided JDK provides tools like compiler, debuggers, etc for code development JRE provides libraries and classes required by JVM to run the program. JVM does not include any tools, but instead, it provides the specification for implementation.
    Summary JRE = + Libraries to execute the application JVM = Runtime environment to execute Java byte code.

    Why Hire A Java Developer

    How to Prepare Java Full Stack Developer Interview for 1-5 YOE | Full Stack web Developer Interview

    For many, 2020 is known as the quarantine year. Most companies who had to lock their doors started strengthening their online presence. Some of them use LinkedIn strategies or any type of social media to connect with their customers. Others opt for a more significant digital presence by building business applications and websites. The results? More loyal customers and engaged users that turn into potential customers.

    If you hire a Java developer, youll have someone on your team capable of designing, developing, and managing Java-based applications, depending of course if youll be hiring an entry-level java developer or a senior one. Different applications such as:

  • Mobile applications
  • Cloud-based applications
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    Project Manager Round Interview Questions For Java Developer

    Project manager interview round can be as daunting as the second round. Here PMs can ask Java developers the following questions:

  • Questions about technology innovations and trends
  • Specifics of the project/work
  • Questions defining candidates leadership qualities, commitment, and success orientation
  • There are a lot of other things project managers ask. According to the answers of the applicants, PMs analyze how good they fit the job offered. Usually, a conversation may start with a general introduction followed by more specific topics about behavioral aspects and the willingness to be completely involved in a new project. It is important for PMs to understand whether a person is a team player because projects success depends greatly on how a team works closely together. Time management skills can also become a subject of the interview as these skills define how productive a person is at a workplace.

    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.

    Read Also: How To Prepare System Design Interview

    What Are The Different Types Of Inheritance In Java

    Java developers must understand the concept of inheritance to use existing classes to build new ones. So, expect this question at a Java job interview. In your answer, provide a brief explanation of each inheritance type.

    Example answer:”Java can support different types of inheritance, such as single inheritance, multiple inheritances, multilevel inheritance, hierarchical inheritance and hybrid inheritance. In single inheritance, a class can extend to only one other class and confers it with its properties. When one class can extend to several classes, it is multiple inheritances. Java and other Object-Oriented programming languages do not support multiple inheritances. You can only achieve it in Java with interfaces.

    In multilevel inheritance, one class can extend to another, and that class can then extend further to yet another class. Hierarchical inheritance is when one class can extend to many sub-classes. Hybrid inheritance is a combination of single inheritance and multiple inheritances.”

    Related:15 Java 8 Interview Questions

    Whats The Difference Between String Stringbuffer And Stringbuilder

    Java Developer Interview Questions

    String is an immutable class. In older JDKs the recommendation when programmatically building a String was to use StringBuffer since this was optimized to concatenate multiple Strings together.

    However, the methods StringBuffer were marked as synchronized, which meant that there was a performance penalty, hence StringBuilder was introduced to provide a non-synchronized way to efficiently concatenate and modify Strings.

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    Where To Go From Here

    Now that youâve got all of 93 Java interview questions – itâs time to put them to good use. If youâre currently looking to hire a Java Developer you should be putting your company out there. Check out our WeAreDevelopers for Companies page. Here you can get access to a community of over 30,000 top-notch developers, set up a company profile they wonât be able to resist and start firing out those questions in no time!

    Q10 What Is Multiple Inheritance Is It Supported By Java

    If a child class inherits the property from multiple classes is known as multiple inheritance. Java does not allow to extend multiple classes.

    The problem with multiple inheritance is that if multiple parent classes have the same method name, then at runtime it becomes difficult for the compiler to decide which method to execute from the child class.

    Therefore, Java doesnt support multiple inheritance. The problem is commonly referred to as Diamond Problem.

    In case you are facing any challenges with these java interview questions, please comment on your problems in the section below.

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    More Important Basic Questions For Java Developers

    Keep in mind that, although Java is already an object-oriented programming language, you may get interview questions on object-oriented programming that are more theoretical, conceptual, and outside general Java programming.

    To prepare yourself, consider the following additional core Java interview questions on OOP:

    • What are classes / objects / abstractions / inheritances in object-oriented programming?
    • Can you name the 5 SOLID object-oriented programming design principles?
    • How do method overloading and method overriding work in OOP or Java?
    • What is an abstract class in Java?

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    Tips To Keep In Mind During The Full Stack Developer Interview

    How to prepare for experienced java developer interview | how to get selected in amazon interview

    You might spend weeks and months preparing for the interview, but nothing can prepare you for D-day. Here are a couple of pro tips to help you deal with the pressure:

    • Think Out Loud: According to experienced full stack developers, when youâre given a problem, discussing strategies with interviewers can be helpful. It helps interviewers understand your thought process and lets you gather information and ideas quickly to process them and solve the problem.
    • Composure: Maintaining your composure while determining a possible solution is critical. Interviewers want candidates that do not succumb to pressure or stress. The ability to handle difficult situations logically and with a calm mind is desirable in a candidate.

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    Q40 Why Java Strings Are Immutable In Nature

    In Java, string objects are immutable in nature which simply means once the String object is created its state cannot be modified. Whenever you try to update the value of that object instead of updating the values of that particular object, Java creates a new string object. Java String objects are immutable as String objects are generally cached in the String pool. Since String literals are usually shared between multiple clients, action from one client might affect the rest. It enhances security, caching, synchronization, and performance of the application.

    Can The Static Methods Be Overridden

    • No! Declaration of static methods having the same signature can be done in the subclass but run time polymorphism can not take place in such cases.
    • Overriding or dynamic polymorphism occurs during the runtime, but the static methods are loaded and looked up at the compile time statically. Hence, these methods cant be overridden.

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    What Are The Advantages Of Hibernate Over Jdbc

    Some of the important advantages of Hibernate framework over JDBC are:

  • Hibernate removes a lot of boiler-plate code that comes with JDBC API, the code looks cleaner and readable.
  • Hibernate supports inheritance, associations, and collections. These features are not present with JDBC API.
  • Hibernate implicitly provides transaction management, in fact, most of the queries cant be executed outside transaction. In JDBC API, we need to write code for transaction management using commit and rollback.
  • JDBC API throws SQLException that is a checked exception, so we need to write a lot of try-catch block code. Most of the times its redundant in every JDBC call and used for transaction management. Hibernate wraps JDBC exceptions and throw JDBCException or HibernateException un-checked exception, so we dont need to write code to handle it. Hibernate built-in transaction management removes the usage of try-catch blocks.
  • Hibernate Query Language is more object-oriented and close to Java programming language. For JDBC, we need to write native SQL queries.
  • Hibernate supports caching that is better for performance, JDBC queries are not cached hence performance is low.
  • Hibernate provides option through which we can create database tables too, for JDBC tables must exist in the database.
  • Hibernate supports JPA annotations, so the code is independent of the implementation and easily replaceable with other ORM tools. JDBC code is very tightly coupled with the application.
  • Top Interview Questions For A Java Developer

    Java Developer Interview Questions and Answers

    To recruit Java developers you should make a list of the questions that are closely connected to the technology. However, we have prepared standard questions you can ask:

  • Provide a clear introduction about your company and project. Introduce yourself and tell how you see a person go about solving issues.
  • Ask your candidate about previous work experience if available. If you talk to a college graduate student ask about his thesis paper or a major subject. Note that some candidates cant talk about their previous projects in detail as they signed NDA agreements.
  • Give a simple programming problem for your candidate to solve. Let it be a problem that can be solved by a developer who is writing code in any of the existing programming languages.
  • Ask a tricky question that can demonstrate how smart a person is in problem-thinking and solving algorithms.
  • Ask a person if he has any question for you. People who are passionate about what they are doing will always have a lot of brilliant questions to ask.
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    What Is The Difference Between Execute Executequery Executeupdate

    Statement execute is used to execute any SQL query and it returns TRUE if the result is an ResultSet such as running Select queries. The output is FALSE when there is no ResultSet object such as running Insert or Update queries. We can use getResultSet to get the ResultSet and getUpdateCount method to retrieve the update count.

    Statement executeQuery is used to execute Select queries and returns the ResultSet. ResultSet returned is never null even if there are no records matching the query. When executing select queries we should use executeQuery method so that if someone tries to execute insert/update statement it will throw java.sql.SQLException with message executeQuery method can not be used for update.

    Statement executeUpdate is used to execute Insert/Update/Delete statements or DDL statements that returns nothing. The output is int and equals to the row count for SQL Data Manipulation Language statements. For DDL statements, the output is 0.

    You should use execute method only when you are not sure about the type of statement else use executeQuery or executeUpdate method.

    Q7 What Are The Different Types Of Inheritance In Java

    Java supports four types of inheritance which are:

  • Single Inheritance: In single inheritance, one class inherits the properties of another i.e there will be only one parent as well as one child class.
  • Multilevel Inheritance: When a class is derived from a class which is also derived from another class, i.e. a class having more than one parent class but at different levels, such type of inheritance is called Multilevel Inheritance.
  • Hierarchical Inheritance: When a class has more than one child classes or in other words, more than one child classes have the same parent class, then such kind of inheritance is known as hierarchical.
  • Hybrid Inheritance: Hybrid inheritance is a combination of two or more types of inheritance.
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    Apart From The Security Aspect What Are The Reasons Behind Making Strings Immutable In Java

    A String is made immutable due to the following reasons:

    • String Pool: Designers of Java were aware of the fact that String data type is going to be majorly used by the programmers and developers. Thus, they wanted optimization from the beginning. They came up with the notion of using the String pool to store the String literals. They intended to decrease the temporary String object with the help of sharing. An immutable class is needed to facilitate sharing. The sharing of the mutable structures between two unknown parties is not possible. Thus, immutable Java String helps in executing the concept of String Pool.
    • Multithreading: The safety of threads regarding the String objects is an important aspect in Java. No external synchronization is required if the String objects are immutable. Thus, a cleaner code can be written for sharing the String objects across different threads. The complex process of concurrency is facilitated by this method.
    • Collections: In the case of Hashtables and HashMaps, keys are String objects. If the String objects are not immutable, then it can get modified during the period when it resides in the HashMaps. Consequently, the retrieval of the desired data is not possible. Such changing states pose a lot of risks. Therefore, it is quite safe to make the string immutable.

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