What are the Benefits of Obtaining an Oracle Java Certification for My Career?

In today’s competitive job market, professionals constantly seek ways to stand out and enhance their skills. One significant way to achieve this is through certifications, and Oracle Java Certification is one of the most sought-after credentials in the IT industry. This article delves into the myriad benefits of obtaining an Oracle Java Certification and how it can propel your career to new heights.

1. Enhanced Job Opportunities

Obtaining an Oracle Java Certification opens doors to a plethora of job opportunities. Companies across the globe recognize and value the certification as it demonstrates a strong foundation in Java programming and related technologies. Certified professionals are often preferred over non-certified candidates for roles such as Java Developer, Software Engineer, and Application Developer. The certification acts as a testament to your commitment to mastering Java, thereby enhancing your employability.

2. Increased Earning Potential

One of the most compelling reasons to pursue an Oracle Java Certification is the potential for higher earnings. Certified Java professionals typically command higher salaries compared to their non-certified counterparts. According to industry surveys, individuals with an Oracle Java Certification can expect a significant increase in their annual salary. This financial benefit makes the certification a worthwhile investment in your career.

3. Comprehensive Knowledge and Skill Development

The process of preparing for Oracle Java Certification exams is rigorous and thorough. It ensures that candidates gain an in-depth understanding of Java programming and its various components. This comprehensive knowledge includes learning about Java SE (Standard Edition), Java EE (Enterprise Edition), and various Java frameworks and libraries. The certification process also enhances your problem-solving and coding skills, making you a more proficient developer.

4. Recognition and Credibility

Being Oracle certified gives you a badge of credibility in the IT industry. Oracle is a globally recognized and respected organization, and its certifications are synonymous with high standards of expertise. When you obtain an Oracle Java Certification, you join an elite group of professionals who are acknowledged for their technical proficiency and dedication to continuous learning. This recognition can be a significant boost to your professional reputation.

5. Career Advancement and Promotion

Certification often acts as a catalyst for career advancement. Many organizations have policies that favor the promotion of certified employees. An Oracle Java Certification can be a decisive factor when it comes to climbing the corporate ladder. It showcases your commitment to professional growth and your ability to handle advanced Java-related projects, making you a prime candidate for senior positions and leadership roles.

6. Networking Opportunities

Being part of the Oracle certified community provides excellent networking opportunities. You can connect with other certified professionals, attend exclusive events, and participate in forums and discussions. Networking can lead to valuable insights, job leads, and collaborations that can further your career. The community support can also be beneficial in staying updated with the latest industry trends and best practices.

7. Access to Oracle Resources and Updates

Certified professionals gain access to exclusive Oracle resources, including software updates, technical support, and training materials. This access ensures that you stay at the forefront of technological advancements and can continuously upgrade your skills. Being up-to-date with the latest Java developments can give you a competitive edge in the job market.

8. Improved Job Performance

The skills and knowledge gained through Oracle Java Certification can directly translate to improved job performance. Certified professionals are equipped to handle complex Java projects more efficiently and effectively. This proficiency can lead to higher productivity, better quality of work, and ultimately, career success. Employers value employees who can contribute significantly to the success of their projects and the organization.

9. Confidence Boost

Achieving certification can be a significant confidence booster. The rigorous preparation and successful completion of the exam validate your expertise and abilities. This confidence can positively impact your job performance and career trajectory. It empowers you to take on challenging projects and positions you as a knowledgeable and skilled professional in your field.

10. Enhanced Problem-Solving Skills

Oracle Java Certification exams are designed to test not just theoretical knowledge but also practical problem-solving skills. Preparing for these exams hones your ability to think critically and solve real-world programming issues efficiently. These enhanced problem-solving skills are invaluable in a fast-paced and ever-evolving IT landscape.

11. Employer Benefits

Employers also benefit from having Oracle certified professionals on their team. Certified employees bring a higher level of expertise and efficiency to their roles, which can lead to better project outcomes and overall organizational success. Companies often support their employees in obtaining certifications by providing resources and incentives, recognizing the value it brings to their workforce.

12. Staying Competitive in the Job Market

In the highly competitive IT job market, staying relevant and competitive is crucial. Oracle Java Certification helps you stay ahead of the curve by validating your skills and knowledge. It distinguishes you from other candidates and demonstrates your commitment to staying current with industry standards and practices.

Conclusion

Obtaining an Oracle Java Certification is a strategic career move that offers numerous benefits, from enhanced job opportunities and increased earning potential to improved job performance and professional recognition. The certification process equips you with comprehensive knowledge, advanced skills, and a network of peers and resources that can significantly boost your career. As the IT industry continues to evolve, staying certified and updated with the latest advancements is essential for sustained career growth and success.

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Oracle Java Time Range Check: Comprehensive Guide

Oracle Java offers a multitude of functionalities for time and date manipulation, essential for developing robust and reliable applications. Among these functionalities, time range checks are pivotal for ensuring that events occur within specified boundaries. This comprehensive guide delves into the intricacies of implementing time range checks in Oracle Java, providing detailed insights and practical examples to help developers master this essential task.

Understanding Time in Oracle Java

Java's time and date API has evolved significantly, especially with the introduction of the java.time package in Java 8, also known as the new Date-Time API. This package addresses many of the issues present in the previous versions and provides a more comprehensive and flexible framework for handling time.

The Importance of the java.time Package

The java.time package simplifies time operations by offering clear and intuitive classes like LocalTime, LocalDate, LocalDateTime, and ZonedDateTime. These classes provide methods to easily manipulate and compare time values.

Key Classes for Time Range Checks:

• LocalTime: Represents a time without a date, such as 10:15:30.
• LocalDate: Represents a date without a time, such as 2024-05-17.
• LocalDateTime: Combines date and time, such as 2024-05-17T10:15:30.
• ZonedDateTime: A date-time with a time-zone in the ISO-8601 calendar system, such as 2024-05-17T10:15:30+01:00[Europe/Paris].

Implementing Time Range Checks

Basic Time Range Check with LocalTime

To check if a given time falls within a specific range, LocalTime is typically used. Here’s an example demonstrating a basic time range check:

import java.time.LocalTime;

public class TimeRangeCheck {

    public static void main(String[] args) {

        LocalTime startTime = LocalTime.of(9, 0);

        LocalTime endTime = LocalTime.of(17, 0);

        LocalTime currentTime = LocalTime.now();

        if (currentTime.isAfter(startTime) && currentTime.isBefore(endTime)) {

            System.out.println("Current time is within the range.");

        } else {

            System.out.println("Current time is outside the range.");

        }

    }

}

Time Range Check with LocalDateTime

For scenarios requiring date and time, LocalDateTime is more appropriate. Here’s an example:

import java.time.LocalDateTime;

public class DateTimeRangeCheck {

    public static void main(String[] args) {

        LocalDateTime startDateTime = LocalDateTime.of(2024, 5, 17, 9, 0);

        LocalDateTime endDateTime = LocalDateTime.of(2024, 5, 17, 17, 0);

        LocalDateTime currentDateTime = LocalDateTime.now();

        if (currentDateTime.isAfter(startDateTime) && currentDateTime.isBefore(endDateTime)) {

            System.out.println("Current date and time are within the range.");

        } else {

            System.out.println("Current date and time are outside the range.");

        }

    }

}

Advanced Time Range Check with ZonedDateTime

When dealing with multiple time zones, ZonedDateTime ensures that the checks consider the time zone differences. Below is an example of how to perform a time range check with ZonedDateTime:

import java.time.ZonedDateTime;

import java.time.ZoneId;

public class ZonedDateTimeRangeCheck {

    public static void main(String[] args) {

        ZonedDateTime startZonedDateTime = ZonedDateTime.of(2024, 5, 17, 9, 0, 0, 0, ZoneId.of("Europe/Paris"));

        ZonedDateTime endZonedDateTime = ZonedDateTime.of(2024, 5, 17, 17, 0, 0, 0, ZoneId.of("Europe/Paris"));

        ZonedDateTime currentZonedDateTime = ZonedDateTime.now(ZoneId.of("Europe/Paris"));

        if (currentZonedDateTime.isAfter(startZonedDateTime) && currentZonedDateTime.isBefore(endZonedDateTime)) {

            System.out.println("Current zoned date and time are within the range.");

        } else {

            System.out.println("Current zoned date and time are outside the range.");

        }

    }

}

Handling Edge Cases in Time Range Checks

Midnight Crossings

One common edge case is when the time range crosses midnight, such as from 10 PM to 2 AM. This scenario requires special handling to avoid incorrect range checks:

import java.time.LocalTime;

public class MidnightCrossingCheck {

    public static void main(String[] args) {

        LocalTime startTime = LocalTime.of(22, 0); // 10 PM

        LocalTime endTime = LocalTime.of(2, 0); // 2 AM

        LocalTime currentTime = LocalTime.now();

        boolean isInRange;

        if (startTime.isAfter(endTime)) {

            isInRange = !currentTime.isBefore(startTime) || !currentTime.isAfter(endTime);

        } else {

            isInRange = !currentTime.isBefore(startTime) && !currentTime.isAfter(endTime);

        }

        if (isInRange) {

            System.out.println("Current time is within the midnight-crossing range.");

        } else {

            System.out.println("Current time is outside the midnight-crossing range.");

        }

    }

}

Inclusive vs. Exclusive Range Boundaries

In some applications, the range boundaries might be inclusive or exclusive. Adjusting the check to include or exclude the boundary times ensures the correct behavior:

import java.time.LocalTime;

public class InclusiveExclusiveRangeCheck {

    public static void main(String[] args) {

        LocalTime startTime = LocalTime.of(9, 0);

        LocalTime endTime = LocalTime.of(17, 0);

        LocalTime currentTime = LocalTime.now();

        boolean isInclusive = true;

        boolean isInRange;

        if (isInclusive) {

            isInRange = !currentTime.isBefore(startTime) && !currentTime.isAfter(endTime);

        } else {

            isInRange = currentTime.isAfter(startTime) && currentTime.isBefore(endTime);

        }

        if (isInRange) {

            System.out.println("Current time is within the range.");

        } else {

            System.out.println("Current time is outside the range.");

        }

    }

}

Practical Applications of Time Range Checks

Scheduling Systems

Time range checks are fundamental in scheduling systems to ensure that appointments or tasks are set within acceptable hours. For instance, booking systems often restrict the booking times to business hours:

import java.time.LocalTime;

public class BookingSystem {

    public static void main(String[] args) {

        LocalTime businessStartTime = LocalTime.of(9, 0);

        LocalTime businessEndTime = LocalTime.of(17, 0);

        LocalTime requestedTime = LocalTime.of(15, 0); // Example booking time

        if (requestedTime.isAfter(businessStartTime) && requestedTime.isBefore(businessEndTime)) {

            System.out.println("Booking time is within business hours.");

        } else {

            System.out.println("Booking time is outside business hours.");

        }

    }

}

Access Control

Time-based access control systems use time range checks to grant or deny access based on the current time. For example, employees might have access to a building only during their shift hours:

import java.time.LocalTime;

public class AccessControl {

    public static void main(String[] args) {

        LocalTime shiftStartTime = LocalTime.of(8, 0);

        LocalTime shiftEndTime = LocalTime.of(18, 0);

        LocalTime accessTime = LocalTime.now();

        if (accessTime.isAfter(shiftStartTime) && accessTime.isBefore(shiftEndTime)) {

            System.out.println("Access granted.");

        } else {

            System.out.println("Access denied.");

        }

    }

}

Conclusion

Time range checks in Oracle Java are essential for ensuring that events and operations occur within designated time frames. Utilizing the java.time package, developers can efficiently implement time range checks for various applications, from scheduling systems to access control mechanisms. By understanding and applying the principles and techniques outlined in this guide, you can ensure accurate and reliable time-based operations in your Java applications.

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How to Effectively Use Java Certification Practice Exams to Boost Your Score

Preparing for a Java certification exam can be daunting. Whether you are aiming for certifications like 1Z0-808, 1Z0-809, 1Z0-811, or more advanced ones such as 1Z0-819, 1Z0-900 and 1Z0-829, practice exams serve as an essential tool in your preparation arsenal. These simulated tests not only familiarize you with the format and style of the questions you'll face but also help pinpoint areas where your understanding may be lacking.

Using practice exams effectively can significantly enhance your chances of achieving a passing score and mastering the professional-level curriculum path for Java certification.

Benefits of Java Certification Practice Exams

Using Java certification practice exams can significantly elevate your preparedness for the actual test day. This preparation not only enhances your understanding of Java but also gives you a hands-on approach to tackling exam-style questions. Here, we will delve into several benefits these practice exams offer to candidates aiming to achieve certification.

Familiarizing Yourself with Exam Format

One of the primary advantages of engaging with Java certification practice exams is they familiarize you with the testing format.

Java certification exams, such as 1Z0-809 or 1Z0-819, have specific structures, often consisting of multiple-choice questions.

By taking practice exams, you get accustomed to the timing, the types of questions, and the overall pacing of the exam. This practice helps minimize any surprises on the actual exam day, allowing you to manage your time efficiently and increase your performance confidence.

Familiarity with the exam format translates directly into reduced exam anxiety and a more strategic approach to answering questions.

Identifying Weak Areas for Improvement

Practice exams serve as a diagnostic tool to highlight your strengths and weaknesses. As you encounter various questions, particularly those you find challenging or get wrong, you begin to see patterns in your knowledge gaps.

Whether it's concepts in Java Standard Edition such as lambdas and streams in the 1Z0-829 exam or debugging and exception handling scenarios in the 1Z0-808 specification, identifying these weak areas provides a focused framework for your study plan.

You can then allocate more time to revise and practice these specific topics, which maximizes the efficiency of your study sessions. This targeted preparation ensures that you bolster your understanding in weaker areas, making you more adept across all areas of the Java platform.

Types of Java Certification Practice Exams

Java certification candidates have access to a variety of practice tests, each designed to cater to different aspects of the learning process. These resources mimic the content and structure of the actual certification exams and can be a pivotal part of your preparation.

Understanding the types of practice exams available can help you choose the right tools to boost your readiness.

Mock Exams

Mock exams are comprehensive practice tests that closely simulate the real certification exam environment. They are designed to be as similar as possible to the actual exam, both in format and difficulty level. Taking mock exams offers several benefits:

• Real Exam Feel: By replicating the pressure and timing of the real exam, mock exams give you a taste of what to expect, helping to ease nerves on exam day.
• Performance Tracking: Many platforms offering mock exams provide detailed performance tracking. This feedback is crucial as it shows your progress and highlights areas that still need improvement.
• Conditioning: Regularly scheduled mock exams can condition your mind and body, getting you used to the exam’s duration and mental stamina required.

A notable strategy is to start taking these mock exams early in your study plan and periodically retake them to track your improvement and adjust your study tactics accordingly.

Exam Simulators

Exam simulators are interactive tools that create a dynamic testing experience. These platforms not only feature a set of questions but also mimic the exam’s technology-based environment. Here's how they can be beneficial:

• Interactive Experience: Simulators often use technology that mirrors the actual exam’s interface, which can be invaluable for becoming comfortable with the navigation and tools you will use on the real exam day.
• Adaptability: Some simulators adjust the difficulty of the questions based on your answers, providing a customized difficulty level that can challenge your knowledge more effectively.
• Immediate Feedback: Unlike some mock exams, simulators usually provide immediate feedback for each question, helping to reinforce learning or correct misunderstandings on the spot.

Utilizing exam simulators can dramatically increase your familiarity with the exam’s digital environment, which is crucial for those who may not be as comfortable with computer-based tests.

Strategies to Maximize Your Score with Java Certification Practice Exams Practice Exams

Utilizing practice exams for Java certification can significantly enhance your preparedness and boost your confidence. Following strategic approaches to leveraging these resources can greatly improve your chances of achieving a high score.

Java Certification Practice Exams: Time Management Techniques

Effective time management is crucial during both your preparation and the actual exam. Here’s how you can optimize your time management skills through practice exams:

• Simulate Real Exam Conditions: Always time yourself as if you are in the actual exam. This helps you get used to the pressure of completing within the allotted time.
• Sectional Timing Practice: Divide the practice exam into sections and allocate specific times to each. This strategy will help you to not spend too much time on one section at the expense of another.
• Analyze Time Spent on Each Question: Post-exam, review how much time you spent on different types of questions. Identify the questions that took the longest time and focus on improving your speed and efficiency in those areas.
• Speed and Accuracy Balance: Work on striking a balance between speed and accuracy. Concentrating solely on speed can lead to mistakes, whereas focusing only on accuracy might cause you to run out of time.

Reviewing and Understanding Correct Answers

Merely taking practice exams is not enough. The real benefit comes from thoroughly reviewing and understanding every answer, particularly the incorrect ones. Here’s how to do this effectively:

• Detailed Review Session: After completing each practice exam, go through each question carefully. For every wrong answer, understand why your chosen answer was incorrect and learn the correct reasoning.
• Cross-Reference with Study Materials: For questions you found challenging, cross-reference the concepts with your study materials. This can help reinforce learning and clarify doubts.
• Keep a Mistake Journal: Maintain a journal to record common mistakes or challenging topics. This helps in identifying patterns and areas needing more focus.
• Discuss with Peers or Mentors: Sometimes discussing complex questions with peers or a mentor can offer new insights and simplifies complicated concepts.

Creating a Study Plan Incorporating Java Certification Practice Exams

A structured study plan integrating practice exams can systematically prepare you for the Java certification test. Here’s how to create one:

• Set Specific Goals: Determine what score you are aiming for and set regular milestones to achieve it.
• Regular Practice Exams: Schedule regular practice exams into your study routine. Start with wider intervals and increase the frequency as you get closer to the exam date.
• Incorporate Different Resources: Utilize a variety of practice exams from different sources to cover a broader range of topics and question formats.
• Allocate Time for Review: Ensure your study plan includes ample time for in-depth review of practice exam results. Adjust your study plan based on these reviews to focus on weaker areas.

Tips for Using Practice Exams Effectively

Using practice exams effectively can transform your preparation and significantly enhance your performance on the actual certification test. The key to utilizing these tools efficiently is to adopt smart strategies that simulate the real exam environment and provide actionable insights into your knowledge and preparation level.

Setting Realistic Goals

To make the most out of Java certification practice exams, start by setting realistic and specific goals for each practice session. This involves understanding what each exam covers and designing your goals to match these topics.

For example, if you are preparing for the 1Z0-809 Java SE 8 Programmer II exam, set goals around mastering specific objectives such as Lambda expressions and using java.util.stream to perform complex data processing.

Break down your study sessions into manageable segments, aiming to improve incrementally with each practice exam taken. For instance:

• -In your first practice session, you might aim to understand the overall exam format and question styles.
• -In subsequent sessions, narrow your focus to improve in areas where your previous scores were weak.

Furthermore, use your practice exam results to set quantitative goals, like aiming to improve your score by a certain percentage with each attempt, ensuring that your study efforts are yielding measurable improvements over time.

Balancing Practice Exams with Other Study Material

While practice exams are invaluable tools for exam preparation, they should not be your only study resource. Balancing practice tests with other study materials such as textbooks, video tutorials, and hands-on projects is vital. This balanced approach ensures that you have a robust understanding of Java and are not just learning to pass the test.

Incorporate these elements into your study plan:

• Use textbooks or online resources to deepen your conceptual understanding of Java.
• Watch video tutorials to visually reinforce complex concepts and procedures.
• Engage with online forums or study groups to interact with fellow test-takers and share insights.
• Work on real Java projects or exercises to apply what you've learned practically.

Such a comprehensive approach helps to solidify your knowledge and provides confidence that goes beyond the practice exams.

Utilizing Retake Opportunities Wisely

Most exam simulators and practice tests offer options to retake the exams multiple times. Use these opportunities wisely to maximize your learning. Initially, use the first few attempts to get familiar with the exam’s format and timing. This can help in adjusting your pace and strategy during the exam without the pressure of having to score well.

After you are comfortable with the format, focus on the following during your retakes:

• Identify patterns in the questions and topics that are often emphasized.
• Understand and analyze your mistakes deeply. Rather than just noting the correct answers, spend time understanding why your answers were wrong and how to think about such questions correctly.
• Experiment with different time management strategies to find what best suits you during the exam condition.

Each retake should be viewed as a learning experience rather than just another attempt. This perspective shifts focus from merely answering questions to actively learning and adapting strategies that will help in the real certification exam.

Using practice exams effectively is crucial in a well-rounded preparation strategy. By setting realistic goals, balancing various forms of study materials, and utilizing retakes productively, you are setting the stage not just for passing but excelling at your Java Certification examination. Remember, the goal is both a deep understanding of Java and an excellent performance on the exam day.

Conclusion

In conclusion, effectively leveraging Java certification practice exams, such as those for 1Z0-829, 1Z0-819, and other similar certifications, is pivotal for not only enhancing your Java skills but also for ensuring you are thoroughly prepared on exam day. By following the structured approach of understanding the exam format, practicing consistently, using quality resources, and simulating real exam scenarios, you can significantly boost your chances of achieving a passing score. Remember, consistency and perseverance are your best tools on this journey. Good luck on your path to Java certification success!

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Benefits You Can Expect From Getting an Oracle Java Certification

The best thing is the Oracle Java certification process is industry recognized. Over the past years, we have seen that certifications have earned the credential for candidates in the industry. It helps software developers improve their skills and allows them to stand out in front of the crowd.

Several vendors provide certifications, like Oracle, Google, Axelon, and many more. Among them, Oracle is well known for giving certificates in varied domains, and one of the most industry-wide recognized certifications is Oracle’s certification in the Java Programming Language.

What Is an Oracle Java Certification?

Oracle Certifies Programmers based on their skill set and knowledge based on the Java Programming Language. When Oracle consents you as a Java professional, it officially declares that you carry the experience set to develop software using Java Programming Language.

Oracle Java Certification is a good benchmark for all experienced Java Professionals and to-be Java Professionals in the US. It certifies that you have the capability and knowledge to develop Java programs.

An Oracle Java certificate is an official recognition from Oracle Corporation - the company that maintains and develops Java technologies - it certifies that you acquired comprehensive, quality, industry-standard knowledge on a specific Java technology: Core Java, Java SE, Java EE, etc. An Oracle Java certification acknowledges your excellence in developing Java applications using that technology. Imagine that your Java programming expertise is like a warranty seal of a high-quality product.

Who Requires to Take Oracle Certification on Java?

Oracle certifies you as a Java programmer means that you hold all the capabilities of developing software. But, it just recognizes your skills; it does not confirm that you will. You require to demonstrate your caliber yourself.

By getting the Oracle Java certification, you are ready to step into this competitive world by learning a new language and applying it as a fresher. Or you are updating your existing skills. Utilizing your current experience and updated skills, you are making credibility to stand in front of the crowd. You are increasing your caliber in front of your team members who are not certified.

If you are a fresher taking Oracle Java certification, you will find a boost in your career. And if you are an experienced professional, you might find new interesting aspects and concepts that you might apply in your practical programming work. You will see a gradual growth in your knowledge.

Benefits of Oracle Java Certification in the Job World

1. Improves Your Knowledge of the Programming Language

The organization where you work always aims to see its employees reach the top professional credits. Oracle Java certification in Java is one such credit. You might be amazed to know that, at times, organizations themselves sponsor your certification as they require more qualified professionals to suffice the client requirements.

In general, certification gives you an add-on to your career and resume. Oracle Java certification improves your existing knowledge base, introduces new aspects of the programming world, and makes you familiar with new concepts that the working world demands. Make it a point to take this Oracle Java certification when you feel your existing knowledge is becoming outdated.

2. Increased Job Opportunities

First, taking OCA or OCP certification does not ensure a new job for you; it certifies you as a professional familiar with all the latest concepts. Rest relies on you how you attain it during your interview. Managers and recruiters are always looking out for Oracle Java Certified Professionals in the market.

It adds to the credibility of the candidate. And adds a good point in the employee’s resume and LinkedIn profile. So, opportunities are many; it relies on how well you grasp the opinions and how well you can use your knowledge to serve the practical requirements.

3. Chance to Become a Better Java Programmer

You earn better knowledge about Java Programming Language by getting the Oracle Java certification. It means that you have a brighter chance of becoming a better developer. It ensures you give all the latest and most updated information about the programming language. It depends on how you adapt and utilize the latest updates in practical coding.

Conclusion

Now at least knowing Oracle Java certifications and their benefits, you would not fall into the rumors of getting a job with the certificate. It just adds a credit to your profile. We do accept that there are brighter opportunities of receiving a hike in your salaries. But even that relies on your caliber and how well you adapt the updates.

There is always cutthroat competition in the market to secure a job. The smart way to land a job is to distinguish yourself from other candidates as much as possible. Oracle Java certifications will give you an edge over the other candidates in the resume shortlist process or during interview rounds. It is like investing in yourself for a better career.

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Quiz yourself: Creating records within a Java sealed-type hierarchy

A record type is always implicitly final, so it cannot be extended by either a regular class or a record.

You’re designing an IoT device controlled by Java. The device has two modes, one for day and one for night. The modes differ in terms of configuration data, and that data should be constant, so you have decided to use Java records for the implementation. Further, since no other mode types are permitted, you have decided to seal the mode hierarchy something like this, but have not decided what the type of should be used to implement the parent of the sealed Mode hierarchy:

Read More: 1Z0-829: Oracle Java SE 17 Developer

public sealed <type> Mode permits DayModeRecord, NightModeRecord {

}

Which statement is true? Choose one.

A. The Mode type must be a class.

B. The Mode type must be a record.

C. The Mode type must be an interface.

D. The Mode may be either a class or an interface.

Answer. Generally, a sealed-type hierarchy can have a class or an interface as its root. The remainder of the hierarchy can contain classes or interfaces, provided all leaf nodes of the hierarchy are either final concrete classes or are non-sealed.

If a leaf element is non-sealed, it can be either a class or an interface.

However, a record is prohibited from using an extends clause, because all record types have java.lang.Record as their parent, and this cannot be made explicit. Consequently, a record cannot inherit from any user-selected class. Therefore, making Mode a class would prevent the two mode records from inheriting from the base. From this, you know that the Mode type must not be a class; therefore, option A and option D are incorrect.

Option B suggests that the Mode type should be a record. However, a record type is always implicitly final, so it cannot be extended by either a regular class or a record. Because of this, option B must be incorrect.

You’ve seen that an interface is permitted for the root (and potentially some further elements) in a sealed-type hierarchy, and although a record is prohibited from explicitly extending anything, records are permitted to implement interfaces. Option C proposes making the Mode type an interface, and it’s clearly not only a valid approach, but it’s the only valid way to create a sealed-type hierarchy where a leaf node in the sealed hierarchy is a record. From this, you can see that option C is correct.

Conclusion. The correct answer is option C.

Source: oracle.com

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It’s time to move your applications to Java 17. Here’s why—and how.

What you need to know about code migration from the previous Long-Term-Support versions of the platform: Java 11 and Java 8

Java 17, the next Long-Term-Support (LTS) version of the Java language and runtime platform, will be officially released on September 14. Unfortunately, many applications still run on old versions of Java, such as the previous LTS versions: Java 11 and Java 8. This article explains why you should upgrade your application and helps you with the actual upgrade to Java 17.

But first, here’s the question many of you may be asking: “Why upgrade?”

Why would anyone even care to upgrade to the latest Java version? It’s reasonable to wonder, especially if your applications run perfectly well on Java 8, Java 11, Java 14, or whatever version you are using. Upgrading to Java 17 requires effort, especially if the goal is to truly leverage the new language features and functionality within the JVM.

Yes, it might require some effort to upgrade depending on the environment and the application. Developers and other team members need to update their local environment. Then the build environments and runtime environments, such as those for production, require an upgrade as well.

Fortunately, many projects and organizations use Docker, which helps a lot in this effort. In my own organization, teams define their own continuous integration/continuous deployment (CI/CD) pipelines, and they run everything in Docker images. Teams can upgrade to the latest Java version by simply specifying that version in their Docker image—and this doesn’t impact other teams who might be running on older Java versions, because those teams can use older Docker images.

The same goes for test and production environments running on Kubernetes. Whenever a team wants to upgrade to a newer Java release, they can change the Docker images themselves and then deploy everything. (Of course, if you still have shared build environments, or other teams who manage your environments, the process might be a bit more challenging.)

Applications might require some changes as well. I’ve noticed that teams find it challenging to estimate that amount of work, resulting in estimates of weeks to months for upgrading one application from Java 8 to Java 11. Those high estimates often result in the company postponing the upgrade because of other priorities.

I managed to upgrade one application, which was estimated to take several weeks, in only a matter of days, mainly due to waiting for builds to complete. That was partly due to years of upgrade experience, but it’s also a matter of just getting started and trying to fix issues along the way. It’s a nice job for a Friday afternoon; seeing how far you get and what challenges are left makes it easier to estimate the remaining work.

However, even after years of experience, I cannot estimate how long an upgrade will take without having in-depth information about the project. A lot depends on how many dependencies your application has. Often, upgrading your dependencies to the latest version resolves many of the issues that would occur during a Java upgrade.

LTS releases

This article keeps referring to Java 8, Java 11, and Java 17 as LTS releases. What does that mean? Here’s a quote from the Oracle Java SE support roadmap:

For product releases after Java SE 8, Oracle will designate a release, every three years, as a Long-Term-Support (LTS) release. Java SE 11 is an LTS release. For the purposes of Oracle Premier Support, non-LTS releases are considered a cumulative set of implementation enhancements of the most recent LTS release. Once a new feature release is made available, any previous non-LTS release will be considered superseded. For example, Java SE 9 was a non-LTS release and immediately superseded by Java SE 10 (also non-LTS), Java SE 10 in turn is immediately superseded by Java SE 11. Java SE 11 however is an LTS release, and therefore Oracle Customers will receive Oracle Premier Support and periodic update releases, even though Java SE 12 was released.

What needs to change during a Java upgrade?

Your application contains code you and your team wrote, and it probably contains dependencies also. If something is removed from the JDK, that might break the code, the dependencies, or both. It often helps to make sure those dependencies are up to date to resolve these issues. Sometimes you might have to wait until a framework releases a new version that is compatible with the latest Java version before you begin the upgrade process. This means that you have a good knowledge of the dependencies as part of the preupgrade evaluation process.

Most functionality isn’t removed all at once from the JDK. First, functionality is marked for deprecation. For instance, Java Architecture for XML Binding (JAXB) was marked for deprecation in Java 9 before being removed in Java 11. If you continuously update, then you see the deprecations and you can resolve any use of those features before the functionality is removed. However, if you are jumping straight from Java 8 to Java 17, this feature removal will hit you all at once.

To view the API changes and, for instance, see which methods are removed or added to the String API in a specific Java version, look at The Java Version Almanac, by Marc Hoffmann and Cay Horstmann.

Multirelease JAR functionality

What if your application is used by customers who still use an old JDK and an upgrade at their site is out of your control? Multirelease JAR functionality, introduced in Java 9 with JEP 238, might be useful because it allows you to package code for multiple Java versions (including versions older than Java 9) inside one JAR file.

As an example, create an Application class (Listing 1) and a Student class (Listing 2) and place them in the folder src/main/java/com/example. The Student class is a class that runs on Java 8.

Listing 1. The Application class

public class Application {

   public static void main(String[] args) {

       Student student = new Student("James ");

       System.out.println("Implementation " + student.implementation());

       System.out.println("Student name James contains a blank: " + student.isBlankName());

   }

}

Listing 2. The Student class written for Java 8

public class Student {

   final private String firstName;

   public Student(String firstName) {

       this.firstName = firstName;

   }

   boolean isBlankName() {

       return firstName == null || firstName.trim().isEmpty();

   }

   static String implementation() { return "class"; }

}

Next to that, create a Student record (Listing 3) that uses not only records (introduced in Java 14) but also the String.isBlank() method (introduced in Java 11), and place it in the folder src/main/java17/com/example.

Listing 3. A Student record using newer Java features

public record Student(String firstName) {

   boolean isBlankName() {

       return firstName.isBlank();

   }

   static String implementation() { return "record"; }

}

Some configuration is required depending on the build tool you use. A Maven example can be found in my GitHub repository. The example is built on Java 17 and creates the JAR file. When the JAR file is executed on JDK 17 or newer, the Student record is used. When the JAR file is executed on older versions, the Student class is used.

This feature is quite useful, for instance, if new APIs offer better performance, because you can use make use of those APIs for customers who have a recent Java version. The same JAR file can be used for customers with an older JDK, without the performance improvements.

Please be aware that all the implementations, in this case, the Student, should have the same public API to prevent runtime issues. Unfortunately build tools don’t verify the public APIs, but some IDEs do. Plus, with JDK 17 you can use the jar –validate command to validate the JAR file.

Something to be aware of is the preview functionality present in some versions of the JDK. Some bigger features are first released as previews and might result in a final feature in one of the next JDKs. Those preview features are present in both LTS and non-LTS versions of Java. The features are enabled with the enable-preview flag and are turned off by default. If you use those preview features in production code, be aware that they might change between JDK versions, which could result in the need for some debugging or refactoring.

More about Java deprecations and feature removals

Before upgrading the JDK, make sure your IDE, build tools, and dependencies are up to date. The Maven Versions Plugin and Gradle Versions Plugin show which dependencies you have and list the latest available version.

Be aware that these tools show only the new version for the artifacts you use—but sometimes the artifact names change, forks are made, or the code moves. For instance, JAXB was first available via javax.xml.bind:jaxb-api but changed to jakarta.xml.bind:jakarta.xml.bind-api after its transition to the Eclipse Foundation. To find such changes, you can use Jonathan Lermitage’s Old GroupIds Alerter plugin for Maven or his plugin for Gradle.

JavaFX. Starting with Java 11, the platform no longer contains JavaFX as part of the specification, and most JDK builds have removed it. You can use the separate JavaFX build from Gluon or add the OpenJFX dependencies to your project.

Fonts. Once upon a time, the JDK contained a few fonts, but as of Java 11 they were removed. If you use, for instance, Apache POI (a Java API for Microsoft Office–compatible documents), you will need fonts. The operating system needs to supply the fonts, since they are no longer present in the JDK. However, on operating systems such as Alpine Linux, the fonts must be installed manually using the apt install fontconfig command. Depending on which fonts you use, extra packages might be required.

Java Mission Control. This is a very useful tool for monitoring and profiling your application. I highly recommend looking into it. Java Mission Control was once included in the JDK, but now it’s available as a separate download under the new name: JDK Mission Control.

Java EE. The biggest change in JDK 11 was the removal of Java EE modules. Java EE modules such as JAXB, mentioned earlier, are used by many applications. You should add the relevant dependencies now that these modules are no longer present in the JDK. Table 1 lists the various modules and their dependencies. Please note that both JAXB and JAX-WS require two dependencies: one for the API and one for the implementation. Another change is the naming convention now that Java EE is maintained by the Eclipse Foundation under the name Jakarta EE. Your package imports need to reflect this change, so for instance jakarta.xml.bind.* should be used instead of javax.xml.bind.*.

Table 1. Java EE modules and their current replacements

CORBA. There is no official replacement for Java’s CORBA module, which was removed in Java 11. However, Oracle GlassFish Server includes an implementation of CORBA.

Nashorn. Java 15 removed the Nashorn JavaScript engine. You can use the nashorn-core dependency if you still want to use the engine.

Experimental compilers. Java 17 removes support for GraalVM’s experimental ahead-of-time (AOT) and just-in-time (JIT) compiler, as explained in the documentation for JEP 410.

Look out for unsupported major files

You might see the error Unsupported class file major version 61. I’ve seen it with the JaCoCo code coverage library and various other Maven plugins. The major version 61 part of the message refers to Java 17. So in this case, it means that the version of the framework or tool you’re using doesn’t support Java 17. Therefore, you should upgrade the framework or tool to a new version. (If you see a message that contains major version 60, it relates to Java 16.)

Be aware that some tools such as Kotlin and Gradle don’t support Java 17 yet, at least as of the time I’m writing this (mid-August 2021). Sometimes it’s possible to work around that, for instance, by specifying Java 16 as the JVM target for Kotlin. However, I expect that Java 17 support will be added soon.

Encapsulated JDK internal APIs

Java 16 and Java 17 encapsulate JDK internal APIs, which impacts various frameworks such as Lombok. You might see errors such as module jdk.compiler does not export com.sun.tools.javac.processing to unnamed module, which means your application no longer has access to that part of the JDK.

In general, I recommend upgrading all dependencies that use those internals and making sure your own code no longer uses them.

If that’s not possible, there is a workaround to still enable your application to access the internals. For instance, if you need access to the comp module, use the following:

--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED

However, use this workaround only as a last resort and preferably only temporarily, because you are circumventing important protections added by the Java team.

Source: oracle.com

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[Fixed] Java lang exceptionininitializererror com sun tools javac code typetags

A quick guide to fix java lang exceptionininitializererror com sun tools javac code typetags with maven.

1. Overview

In this tutorial, We’ll learn how to fix the error “Java lang exceptionininitializererror com sun tools javac code typetags” when working with maven build.

2. Fix 1 – Java lang exceptionininitializererror com sun tools javac code typetags

Fixing this issue is by providing the correct java version.

In the pom.xml file, you might be giving the java version as below.

<maven.compiler.source>1.11</maven.compiler.source>

<maven.compiler.target>1.11</maven.compiler.target>

Below is the complete pom.xml file for reference.

<project xmlns="http://maven.apache.org/POM/4.0.0"

         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>

    <artifactId>Deep</artifactId>

    <version>1.0-SNAPSHOT</version>

    <properties>

        <maven.compiler.source>1.11</maven.compiler.source>

        <maven.compiler.target>1.11</maven.compiler.target>

        <dl4j.version>0.9.1</dl4j.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>org.nd4j</groupId>

            <artifactId>nd4j-native-platform</artifactId>

            <version>${dl4j.version}</version>

        </dependency>

        <dependency>

            <groupId>org.deeplearning4j</groupId>

            <artifactId>deeplearning4j-core</artifactId>

            <version>${dl4j.version}</version>

        </dependency>

        <dependency>

            <groupId>org.datavec</groupId>

            <artifactId>datavec-api</artifactId>

            <version>${dl4j.version}</version>

        </dependency>

        <dependency>

            <groupId>org.nd4j</groupId>

            <artifactId>nd4j-api</artifactId>

            <version>1.0.0-beta3</version>

        </dependency>

        <dependency>

            <groupId>org.deeplearning4j</groupId>

            <artifactId>deeplearning4j-play_2.11</artifactId>

            <version>0.9.1</version>

        </dependency>

    </dependencies>

</project>

This error may be appearing from jdk version after 1.9. and version has to be as 10 or 11 or 12 or 14 or 17.

And java versions should not start with “1.xx” after 1.9 versions. So, you provide the java version as 1.XX then you will see mostly “Java lang exceptionininitializererror” error.

To fix this error you need to change the java version as follows.

<maven.compiler.source>11</maven.compiler.source>

<maven.compiler.target>11</maven.compiler.target>

3. Fix 2 – Java lang exceptionininitializererror com sun tools javac code typetags

If the above fix does not work that means any one of the dependencies are needed to have the higher java versions.

You can find all transitive dependencies using “mvn dependency:tree” command 

For example, if you are using deeplearning4j-core.jar file then you may need to get the latest lombak jar file to fix the issue.

Add the below jar as a dependency in pom.xml file.

<dependency>

  <groupId>org.projectlombok</groupId>

  <artifactId>lombok</artifactId>

  <version>1.18.2</version>

  <scope>provided</scope>

</dependency>

4. Fix 3 – Java lang exceptionininitializererror com sun tools javac code typetags

If the above two solutions did not work then you need to change JAVA_HOME to the latest one or you need to change the jdk version in the eclipse.

Source: javacodegeeks.com

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Introduction to Hypermedia REST APIs

Introduction

When browsing the web we typically navigate from one site to another by following Hyperlinks. Those links make the web for humans discoverable.

Hypermedia APIs provide the same discoverability for services. According to Roy Fielding Hypermedia is an essential part of a REST API and the Richardson REST Maturity Model describes Hypermedia as the final step to the glory of REST. So, Hypermedia seems to be quite an important thing for REST. However, in my experience, Hypermedia is used very rarely. This is a bit sad because Hypermedia provides some nice features to APIs.

Resource representations with links

Let's start with a simple example without Hypermedia. Assume we want to create a resource that provides information about an order. It might look like this:

GET /orders/123

{
    "buyer_id": 456,
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "payment_date": null,
    "status": "open",
    "items": [
        {
            "product_id" : 789,
            "quantity": 1,
            "price": 4.99
        }
    ]
}

Note that the fields buyer_id and product_id are references to other resources. If the client wants to get more information about the buyer, it has to construct a new request URI like this:

String buyerUrl = "/customer/" + order.getBuyerId();

Here the client has to know the exact URI format of related resources. This is similar to surfing the web without using hyperlinks. Instead of clicking on links we have to manually update the browser request line for every sub page we want to visit.

To add Hypermedia support to our order representation, we have to replace IDs with links to related resources.

For example:

{
    "buyer_url": "/customers/456",
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "payment_date": null,
    "status": "open",
    "items": [
        {
            "product_url" : "/products/789",
            "quantity": 5,
            "price": 4.99
        }
    ]
}

We now created links between related resources. A client does no longer have to care about IDs and URI construction. To get buyer information the client just has to send a GET request to the value of buyer_url.

Hypermedia response formats typically group links together in a separate JSON object. It is also a good idea to use a JSON object to represent a link. This gives us the option to add more information to links later.

If we apply this to our order representation it might look like this:

{
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "payment_date": null,
    "status": "open",
    "items": [
        {
            "quantity": 5,
            "price": 4.99,
            "links" : [
                { "rel": "product", "href": "/products/789" }
            ]
        }
    ],
    "links" : [
        { "rel": "buyer", "href": "/customers/456" }
    ]
}

With the rel field we describe the type of the resource relation while href contains the actual link (more on this later).

State Transitions (HATEOAS)

So far we only used links to indicate relations to other resources. Links can also be used to indicate possible actions on a resource. For example, orders can be paid and cancelled. We can use links to point to these operations:

{
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "status": "open",
    "payment_date": null,
    "items": [ ... ],
    "links" : [
        { "rel": "buyer", "href": "/customers/456" },
        { "rel": "payment", "href": "/orders/123/payment" },
        { "rel": "cancellation", "href": "/orders/123/cancellation" }
    ]
}

In order to cancel an order we can now simply send a PUT request to the cancellation link. After cancelling the order, the resource representation might look like this:

{
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "status": "cancelled",
    "payment_date": null,
    "items": [ ... ],
    "links" : [
        { "rel": "buyer", "href": "/customers/456" },
    ]
}

Note that the order status has changed and the links for cancellation and payment are gone. Of course a cancelled order cannot be cancelled again and paying for a cancelled order makes no sense. So links do not just point to actions, they also tell us which actions are possible in the current resource status.

This is called Hypermedia as the Engine of Application State (HATEOAS). HATEOAS can transform a REST API into a state machine over HTTP.

More on Links

We used quite a few links so far. So, it's a good point to look into a few details.

The link attributes rel and href come from the attributes of the <a> tag that is used in HTML to represent links. A common set of link relations (like first, next, previous, etc.) has been standardized by IANA. You can find those relations on the IANA website. It is a good idea to take a look at this list before you come up with your own new rel type.

It is also a good practice to include a link to the current resource, named self. For example:

GET /orders/123

{
    ...
    "links" : [
        { "rel": "self", "href": "/orders/123" },
        ...
    ]
}

Links might not always point to exact resources. It is also possible to create links that contain placeholders or optional parameters. For example, the order list might contain a search-by-status link that contains a status request parameter:

GET /orders

{
    ...
    "links" : [
        { "rel": "self", "href": "/orders" },
        { "rel": "search-by-status", "href": "/orders{?status}" },
        ...
    ]
}

Clients can use that link to filter the order list by a specific order status. For example, this might be a valid request:

GET /orders?status=open

These templates are called URI Templates (defined in RFC 6570). The RFC is a good source for more information.

Links are also an important part of your API documentation. Instead of documenting exact resource URIs you should document possible link relations for your resources. The client needs to know what a specific links does and how it should be used (HTTP method, request body if required, etc.)

The API entry point

If clients do not know any resource URIs they need some entry point for an initial request. This initial entry point then provides links to accessible resources. An API entry point for our example API might look like this:

GET /

{
    "version": "1.2.3",
    "description": "Example API to manage orders",
    "links": [
        { "rel": "orders", "href": "/orders" },
        { "rel": "customers", "href": "/customers"},
        { "rel": "customer-by-id", "href": "/customer/{id}"},
        { "rel": "customer-by-email", "href": "/customer{?email}"},
        ...
    ]
}

With URI templates we can make sure clients do not need to browse through large collections in order to find a needed resource.

Hypermedia response formats

So far we just added links elements to our JSON representation. However, it can be a good idea to look at some common Hypermedia response formats before building a Hypermedia REST API. Unfortunately there is no single standard format. Instead, we can choose from a lot of different formats.

Here are some examples:

◉ HAL (Hypertext Application Language)
◉ JSON LD (JSON for Linking Data)
◉ Collection+JSON
◉ Siren
◉ JSON Hyper Schema

I would recommend looking at HAL first. HAL is quite simple and one of the formats that is widely supported by libraries. Besides standard REST clients you can use tools like HAL explorer to interact with APIs that use HAL.

Why is this useful and what are the downsides?

Introducing Hypermedia to REST APIs comes with a lot of benefits. It reduces coupling between the server and clients. Servers are able to refactor and evolve their URI structure without breaking clients. Clients no longer need to construct request URIs.

It also reduces the logic required on the client. Let's recap the previous example with the order that can be cancelled or paid. However, this time without links:

{
    "order_date": "2020-15-08T09:30:00",
    "total_price": 4.99,
    "status": "open",
    "payment_date": null,
    "items": [ ... ],
}

How does the client decide if it is possible to cancel or pay this order? Maybe an order can be cancelled as long as it is in open state? And it is possible to pay an order as long as it is in open state and payment_date is null?

This logic is already present on the server and can be communicated with HATEOAS. So instead of duplicating logic the client has just to check if a specific link is present. For example: If the cancellation link is present, it is possible to cancel the order and therefore the Cancel order button should be shown in the user interface.

The same approach works great for communicating allowed operations. The server already contains the logic to decide what a user is allowed to do based on his permissions/roles. So, if a user has no permission to cancel an order, don't add a cancellation link.

Those points are all great, but what are the downsides?

Adding links for resource relations and state transitions can be a significant effort on the server side. You have to construct links, list possible state transitions and check if the client has the permissions use them. This effort is only useful if clients actually make use of the Hypermedia elements provided by the API and do not use hardcoded URIs.

Using Hypermedia can also significantly increase the response size.

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How to reverse bits of an integer in Java?

In this Java article, you will learn how to reverse bits of an integer in Java. This is one of the common coding problems which is often asked during phone round of technical interviews on companies like Amazon, Google, and Microsoft. If you have appeared in any programming interviews then there is a good chance that you might have already seen this problem before. If you know the solution then you are in a good place but if you don't know the solution then don't disappoint as many experienced Java developers also struggle to solve this problem. There are a couple of reasons for that, first not every Java developer is good with the bitwise operator, also understanding binary is not every programmer's cup of tea.

This is also a popular LeetCode coding problem, which I haven't tried to submit my solution, you can submit it. You may need to make some changes as they also have test cases which is run against the solution.

How to reverse bits of an integer in Java

Anyway, let's focus on the coding problem in the hand, here is the problem statement and sample input  and output given by interviewer:

Statement:  Given an integer, reverse its bit sequence.
Sample Input:  00000000000000001111111111111110
Sample Output: 01111111111111110000000000000000

This is a crucial junction in coding interviews. The interviewer has given you the problem and now either you can start working on them or spend some time thinking about it and ask some relevant questions to the interviewer to show that you pay attention to details and have good knowledge of how things work inside the machine.

In this problem, It is necessary to know whether the decimal number being passed as input is of type byte (8-bit) or short (16-bit) or int (32-bit) or long (64-bit): because Java will discard leading zeroes. Yes, that's the devil in the detail which many Java programmers don't know.

For example, if number = 0011010, Java will trim it to 11010 and then cause the reverse to look like 1011.  Under such cases, your reverse algorithm may not work.  To keep things simple, the presented algorithm treats int (32-bit)  inputs.

Java Program to reverse bits of an Integer in Java

Here is my sample program to reverse bits of an integer in Java. In this program, I have used an interactive algorithm to reverse all the bits of a given integer number. The number is passed as String from the console and that's why I have first converted given String to Integer using Integer.parseInt() method.

In some cases, the Interviewer can also ask why you use that particular method and why not Integer.valueOf() so be prepare for that.  If you need an answer then you can also see this article.  After that, I pass that integer to our method called the reverseBits(int number) which reverse the bits one at a time.

/**
 * Java Program to reverse bit sequence of an integer.
 * input : 11111111111111111111111111111110
 * output : 01111111111111111111111111111111
 *
 * @author WINDOWS 8
 */

public class ReverseBitsDemo {

    public static void main(String args[]) {

        System.out.println("Testing our reverseBits() method by"
                + " reversing ints in Java");
        String number = "000000000000000000000000000001";
        String expected = "10000000000000000000000000000000";
     
        int binary = Integer.parseInt(number, 2);
        int actual = reverseBits(binary);
     
        System.out.println("original number : " + number);
        System.out.println("reversed number : "
                       + Integer.toBinaryString(actual));
     
        System.out.println(expected.equals(Integer.toBinaryString(actual)));

    }

    /*
     * Java method to reverse bits of specified integer
     */
    public static int reverseBits(int number) {
        int sizeOfInt = 32;
        int reverse = 0;
        for (int position = sizeOfInt - 1; position &gt; 0; position--) {
            reverse += ((number &amp; 1) &lt;&lt; position);
            number &gt;&gt;= 1;
        }
        return reverse;
    }

}

Output
Testing our reverseBits() method by reversing ints in Java
original number : 000000000000000000000000000001
reversed number : 10000000000000000000000000000000
true

That's all about how to reverse bits of an integer in Java. This is the brute force solution and there are some clever solutions also possible using a bitwise operator. If you know one, feel free to post into comments, that will help our readers a lot. I'll also be going to update the article with the top 3 clever solutions posted on comments.

This is also a popular LeetCode coding problem, which I haven't tried to submit my solution, you can and if you need more coding problems, particularly based upon bit manipulation then LeetCode has some good ones. If you need some resources to level up your essential skills, the following courses are highly recommended.

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