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10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Cracking Java Interview in 2024 30 Curated Questions to Sharpen Your Programming Edge! Vahe Aslanyan · Follow...

10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Cracking Java Interview in 2024 30 Curated Questions to Sharpen Your Programming Edge! Vahe Aslanyan · Follow Published in LunarTech 18 min read · Oct 31, 2023 Listen Share Cracking Java Interview https://lunartech.ai/ and https://www.vaheaslanyan.com/ In today’s dynamic corporate landscape, where technology is at the heart of innovation and progress, Java remains a cornerstone of software development. Its versatility, robustness, and scalability have rendered it indispensable, making Java interviews a critical gateway for aspiring and seasoned developers alike. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 1/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Java has consistently maintained its prominence across industries, with over 95% of enterprise desktops worldwide running Java. This ubiquity extends to server-side applications, where Java enjoys a staggering 90% market share. The demand for skilled Java developers has surged, reflected in a substantial increase in job postings seeking Java expertise. Excelling in these interviews not only secures a coveted position but also offers the opportunity to contribute to groundbreaking projects. This guide, “Cracking Java Interview: 30 Curated Questions to Sharpen Your Programming Edge,” is designed to empower Java enthusiasts. It’s not just a compilation of questions and answers; it’s a comprehensive resource meticulously curated to equip you with the essential knowledge needed to excel in Java interviews. Within these pages, you will find a carefully curated selection of 30 crucial Java interview questions, frequently encountered in interviews, and delving into core Java concepts. More than mere questions, this guide offers concise, answers, meticulously crafted to provide you with the depth and clarity needed to grasp the concepts thoroughly. Outline: 1. What is Java? 2. Explain the difference between JDK, JRE, and JVM. 3. How does the ‘public static void main(String[] args)’ method work? 4. What is bytecode in Java? 5. Differentiate between overloading and overriding. 6. What is the Java ClassLoader? 7. Can we override the static method in Java? 8. Describe the different access modifiers in Java. 9. What is the difference between an abstract class and an interface? 10. How does the ‘finally’ block differ from the ‘finalize’ method in Java? https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 2/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech 11. Explain the concept of Java packages. 12. What are Java annotations? 13. How does multi-threading work in Java? 14. Explain the difference between throw and throws in Java. 15. What is the significance of the transient keyword? 16. How do you ensure thread safety in Java? 17. Explain the Singleton pattern. 18. What are Java Streams? 19. What are the primary differences between ArrayList and LinkedList ? 20. How do HashSet , LinkedHashSet , and TreeSet differ? 21. Differentiate between HashMap and ConcurrentHashMap. 22. Describe the contract between hashCode() and equals() methods. 23. What is Java reflection? 24. How do you create a custom exception in Java? 25. What is the difference between a checked and unchecked exception? 26. What are generics? Why are they used? 27. Explain the concept of Java Lambda Expressions. 28. What is the diamond problem in inheritance? 29. Describe the difference between fail-fast and fail-safe iterators. 30. What is type erasure in Java generics? https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 3/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech What is Java https://lunartech.ai/ and https://www.vaheaslanyan.com/ What is Java? Java is a high-level, object-oriented programming language known for its platform independence. It allows developers to write code once and run it anywhere using the Java Virtual Machine (JVM). Explain the difference between JDK, JRE, and JVM. JDK (Java Development Kit): This is a software package that provides developers with the tools and utilities necessary to develop, compile, and run Java applications. JRE (Java Runtime Environment): A subset of the JDK, the JRE contains the essential components, including the JVM, to run Java applications but not to develop them. JVM (Java Virtual Machine): An abstract computing machine, the JVM enables Java bytecode to be executed, providing the platform independence Java is known for. How does the ‘public static void main(String[] args)’ method work? This method is the entry point for Java applications. The public modifier means it’s accessible from other classes, static denotes it’s a class-level method, and void indicates it doesn’t return any value. The argument String[] args allows command- line arguments to be passed to the application. What is bytecode in Java? https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 4/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Bytecode is an intermediate, platform-independent code that Java source code is compiled into. It is executed by the JVM, enabling the “write once, run anywhere” capability. Differentiate between overloading and overriding. Overloading: This occurs when two or more methods in the same class share the same name but have different parameters. It’s a compile-time concept. Overriding: In this case, a subclass provides a specific implementation for a method already defined in its superclass. It’s a runtime concept. Java ClassLoader https://lunartech.ai/ and https://www.vaheaslanyan.com/ What is the Java ClassLoader? The Java ClassLoader is a part of the JRE that dynamically loads Java classes into the JVM during runtime. It plays a crucial role in Java’s runtime environment by extending the core Java classes. Can we override the static method in Java? No, we cannot override static methods. While a subclass can declare a method with the same name as a static method in its superclass, this is considered method hiding, not overriding. Describe the different access modifiers in Java. Private: Accessible only within the class. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 5/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Default (no modifier): Accessible within the same package. Protected: Accessible within the same package and by subclasses. Public: Accessible from any other class. What is the difference between an abstract class and an interface? Abstract Class: Can have both abstract (unimplemented) and concrete (implemented) methods. It can also have instance variables. A class can extend only one abstract class. Interface: Contains only abstract methods (though default and static methods are allowed since Java 8). A class can implement multiple interfaces. How does the ‘finally’ block differ from the ‘finalize’ method in Java? Finally Block: Used in exception handling, the finally block always executes, whether an exception is thrown or not. It's typically used for resource cleanup. Finalize Method: This is a protected method of the Object class, called by the garbage collector before an object is discarded to allow resource release. Explain the concept of Java packages. Java packages are a way of organizing and structuring classes and interfaces in Java applications. They provide a means to group related code together. Packages help prevent naming conflicts, enhance code readability, and facilitate code reusability. For example, consider a banking application. You might have packages like com.bank.accounts , com.bank.customers , and com.bank.transactions. These packages contain classes and interfaces specific to their respective functionalities. In essence, Java packages are like directories or folders in a file system, organizing code and making it more manageable. What are Java annotations? Java annotations are metadata that can be added to Java source code. They provide information about the code to the compiler or runtime environment. Annotations do not directly affect the program’s functionality; instead, they convey instructions to tools or frameworks. A common use of annotations is for marking classes or methods as belonging to a specific framework or for providing additional information to tools like code analyzers, build tools, or even custom code generators. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 6/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech For example, the @Override annotation indicates that a method is intended to override a method from a superclass, helping catch coding errors during compilation. Another example is @Deprecated , which indicates that a method or class is no longer recommended for use. How does multi-threading work in Java? Multi-threading in Java allows a program to execute multiple threads concurrently. Threads are lightweight processes within a program that can run independently. Java provides a rich set of APIs and built-in support for multi-threading. Threads in Java are typically created by either extending the Thread class or implementing the Runnable interface. Once created, threads can be started using the start() method, causing them to run concurrently. Java’s multi-threading model ensures that threads share resources like memory and CPU time efficiently while providing mechanisms like synchronization and locks to control access to shared data. Multi-threading is useful for tasks such as improving application responsiveness, utilizing multi-core processors, and handling concurrent operations, as often seen in server applications. Explain the difference between throw and throws in Java. Throw: throw is used within a method to explicitly throw an exception when a certain condition is met. It is used to indicate that an exceptional situation has occurred within the method, and the program should exit the normal execution flow and transfer control to an appropriate exception-handling block (such as a try-catch block). You typically use throw to create and throw custom exceptions or to propagate exceptions that have occurred within your code. public void doSomething(int value) { if (value < 0) { throw new IllegalArgumentException("Value cannot be negative"); } https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 7/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech // Rest of the code } Throws: throws is used in the method signature to declare that a method may throw one or more exceptions. It informs the caller of the method about the potential exceptions that need to be handled when invoking the method. It doesn’t actually throw exceptions; instead, it documents the exceptions that the method might throw. This is important for the caller, as it allows them to be aware of and handle any exceptions that could occur when using the method. public void someMethod() throws IOException, InterruptedException { // Method code that may throw IOException or InterruptedException } In summary, throw is used inside a method to raise an exception, while throws is used in the method signature to declare which exceptions might be thrown by that method. These keywords play complementary roles in Java's exception handling mechanism, helping to make code more robust and maintainable by properly handling exceptional situations. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 8/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Java Transient Keyword https://lunartech.ai/ and https://www.vaheaslanyan.com/ What is the significance of the transient keyword? The transient keyword in Java is used to indicate that a field should not be serialized when an object of a class is converted to a byte stream (for example, when using Java Object Serialization). This is significant when you have fields in a class that you do not want to include in the serialized form, perhaps because they are temporary, derived, or contain sensitive information. Example: import java.io.Serializable; public class Person implements Serializable { private String name; private transient String temporaryData; // This field won't be serialized // Constructors, getters, setters... } How do you ensure thread safety in Java? https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 9/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Thread safety in Java is achieved by synchronizing access to shared resources, ensuring that multiple threads can’t simultaneously modify data in a way that leads to inconsistencies or errors. You can ensure thread safety through synchronization mechanisms like synchronized blocks, using thread-safe data structures, or utilizing concurrent utilities from the java.util.concurrent package. public class SharedCounter { private int count = 0; // Synchronized method ensures thread safety public synchronized void increment() { count++; } public int getCount() { return count; } public static void main(String[] args) { final SharedCounter counter = new SharedCounter(); Runnable task = () -> { for (int i = 0; i < 10000; i++) { counter.increment(); } }; Thread thread1 = new Thread(task); Thread thread2 = new Thread(task); thread1.start(); thread2.start(); try { thread1.join(); thread2.join(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } System.out.println("Final Count: " + counter.getCount()); } } https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 10/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech In the code above, we have a SharedCounter class with a synchronized increment method, ensuring that only one thread can increment the count variable at a time. This synchronization mechanism prevents data inconsistencies when multiple threads access and modify the shared count variable. We create two threads ( thread1 and thread2 ) that concurrently increment the counter. By using synchronized methods or blocks, we guarantee thread safety, and the final count will be accurate, regardless of thread interleaving. Explain the Singleton pattern. The Singleton pattern is a design pattern that ensures a class has only one instance and provides a global point of access to that instance. It is achieved by making the constructor of the class private, creating a static method to provide a single point of access to the instance, and lazily initializing the instance when needed. Implementation without Singleton: Let’s imagine a scenario where you want to establish a database connection. Without the Singleton pattern, every time you’d need a connection, you might end up creating a new one. public class DatabaseConnectionWithoutSingleton { public DatabaseConnectionWithoutSingleton() { System.out.println("Establishing a new database connection..."); } public void query(String SQL) { System.out.println("Executing query: " + SQL); } } Now, imagine initializing this connection multiple times in different parts of your application: DatabaseConnectionWithoutSingleton connection1 = new DatabaseConnectionWithoutS https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 11/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech DatabaseConnectionWithoutSingleton connection2 = new DatabaseConnectionWithoutS For the above code, “Establishing a new database connection…” would be printed twice, implying two separate connections were created. This is redundant and can be resource-intensive. Implementation with Singleton: With the Singleton pattern, even if you attempt to get the connection multiple times, you’d be working with the same instance. public class DatabaseConnectionWithSingleton { private static DatabaseConnectionWithSingleton instance; private DatabaseConnectionWithSingleton() { System.out.println("Establishing a single database connection..."); } public static synchronized DatabaseConnectionWithSingleton getInstance() { if (instance == null) { instance = new DatabaseConnectionWithSingleton(); } return instance; } public void query(String SQL) { System.out.println("Executing query: " + SQL); } } Initializing this connection multiple times: DatabaseConnectionWithSingleton connection1 = DatabaseConnectionWithSingleton.g DatabaseConnectionWithSingleton connection2 = DatabaseConnectionWithSingleton.g https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 12/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech For the above code, “Establishing a single database connection…” would be printed just once, even though we’ve called getInstance() twice. What are Java Streams? Java Streams are a powerful abstraction for processing sequences of elements, such as collections, arrays, or I/O channels, in a functional and declarative style. They provide methods for filtering, mapping, reducing, and performing various transformations on data. Streams can significantly simplify code and improve readability when working with data collections. Difference between ArrayList and LinkedList https://lunartech.ai/ and https://www.vaheaslanyan.com/ What are the primary differences between ArrayList and LinkedList? ArrayList and LinkedList are both implementations of the List interface. The primary differences between them lie in their internal data structures. ArrayList uses a dynamic array to store elements, offering fast random access but slower insertions and deletions. LinkedList uses a doubly-linked list, which provides efficient insertions and deletions but slower random access. How do HashSet, LinkedHashSet, and TreeSet differ? HashSet stores elements in an unordered manner, offering constant-time complexity for basic operations. LinkedHashSet maintains the order of insertion, providing ordered iteration of elements. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 13/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech TreeSet stores elements in a sorted order (natural or custom), offering log(n) time complexity for basic operations. import java.util.HashSet; import java.util.LinkedHashSet; import java.util.TreeSet; public class SetPerformanceExample { public static void main(String[] args) { int numElements = 1000000; long startTime = System.nanoTime(); HashSet hashSet = new HashSet(); for (int i = 0; i < numElements; i++) { hashSet.add(i); } long endTime = System.nanoTime(); long hashSetTime = endTime - startTime; startTime = System.nanoTime(); LinkedHashSet linkedHashSet = new LinkedHashSet(); for (int i = 0; i < numElements; i++) { linkedHashSet.add(i); } endTime = System.nanoTime(); long linkedHashSetTime = endTime - startTime; startTime = System.nanoTime(); TreeSet treeSet = new TreeSet(); for (int i = 0; i < numElements; i++) { treeSet.add(i); } endTime = System.nanoTime(); long treeSetTime = endTime - startTime; System.out.println("HashSet Time (ns): " + hashSetTime); System.out.println("LinkedHashSet Time (ns): " + linkedHashSetTime); System.out.println("TreeSet Time (ns): " + treeSetTime); } } In this code, we add a large number of elements to each type of set (HashSet, LinkedHashSet, and TreeSet) and measure the time it takes to perform this operation. This demonstrates the performance characteristics of each set type. Typically, you will observe that HashSet performs the fastest for adding elements https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 14/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech since it doesn’t maintain any specific order, followed by LinkedHashSet, and TreeSet, which maintains a sorted order. HashSet Time (ns): 968226 LinkedHashSet Time (ns): 1499057 TreeSet Time (ns): 2384328 This output demonstrates the time taken (in nanoseconds) to add one million elements to each of the three sets: HashSet, LinkedHashSet, and TreeSet. As you can see, HashSet is the fastest, followed by LinkedHashSet, and TreeSet is the slowest due to its need to maintain elements in sorted order. Differentiate between HashMap and ConcurrentHashMap. HashMap is not thread-safe and is suitable for single-threaded applications. ConcurrentHashMap, on the other hand, is designed for concurrent access and supports multiple threads without external synchronization. It provides high concurrency and performance for read and write operations. Describe the contract between hashCode() and equals() methods. The contract between hashCode() and equals() methods states that if two objects are equal (equals() returns true), their hash codes (hashCode()) must also be equal. However, the reverse is not necessarily true: objects with equal hash codes may not be equal. Adhering to this contract is crucial when using objects as keys in hash- based collections like HashMap. What is Java reflection? Java reflection is a feature that allows you to inspect and manipulate the metadata of classes, methods, fields, and other program elements at runtime. It enables you to perform tasks such as dynamically creating objects, invoking methods, and accessing fields, even for classes that were not known at compile time. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 15/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Custom Exception in Java https://lunartech.ai/ and https://www.vaheaslanyan.com/ How do you create a custom exception in Java? You can create a custom exception in Java by extending the Exception class or one of its subclasses. By doing so, you can define your exception with specific attributes and behaviors tailored to your application’s needs. Example: public class CustomException extends Exception { public CustomException(String message) { super(message); } } What is the difference between a checked and unchecked exception? Checked exceptions are exceptions that must be either caught using a try-catch block or declared in the method signature using the throws keyword. Unchecked exceptions (usually subclasses of RuntimeException) do not require such handling. Checked exceptions are typically used for recoverable errors, while unchecked exceptions represent programming errors or runtime issues. Here is a code to illustrate checked and unchecked exceptions. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 16/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech // Checked Exception (IOException) import java.io.File; import java.io.FileReader; import java.io.IOException; public class CheckedExceptionExample { public static void main(String[] args) { try { File file = new File("example.txt"); FileReader reader = new FileReader(file); // Perform file reading operations reader.close(); } catch (IOException e) { // Handle the checked exception System.err.println("An IOException occurred: " + e.getMessage()); } } } In this code, we attempt to read a file using FileReader, which may throw a checked exception called IOException. To handle this exception, we enclose the file reading code in a try-catch block specifically catching IOException. This is an example of how you handle checked exceptions, which are typically used for recoverable errors like file not found or I/O issues. Now, let’s take a look at an example of an unchecked exception: // Unchecked Exception (ArithmeticException) public class UncheckedExceptionExample { public static void main(String[] args) { int dividend = 10; int divisor = 0; try { int result = dividend / divisor; // This will throw an ArithmeticEx System.out.println("Result: " + result); } catch (ArithmeticException e) { // Handle the unchecked exception System.err.println("An ArithmeticException occurred: " + e.getMessa } } https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 17/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech } In this code, we attempt to divide an integer by zero, which leads to an unchecked exception called ArithmeticException. Unchecked exceptions do not require explicit handling using a try-catch block. However, it’s good practice to catch and handle them when you anticipate such issues. These exceptions often represent programming errors or runtime issues. What are generics? Why are they used? Generics in Java are a powerful feature that allows you to create classes, interfaces, and methods that operate on types. They provide a way to define classes or methods with a placeholder for the data type that will be used when an instance of the class is created or when a method is called. Generics are used to make your code more reusable, type-safe, and less error-prone by allowing you to write generic algorithms that work with different data types. They help eliminate the need for typecasting and enable compile-time type checking. For example, consider the use of a generic class to create a List of integers: List numbers = new ArrayList(); numbers.add(1); numbers.add(2); int sum = numbers.get(0) + numbers.get(1); Generics ensure that you can only add integers to the list and that you don’t need to perform explicit typecasting when retrieving elements from the list. Explain the concept of Java Lambda Expressions. Lambda expressions in Java are a concise way to express instances of single-method interfaces (functional interfaces) using a more compact syntax. They facilitate functional programming by allowing you to treat functions as first-class citizens. Lambda expressions consist of a parameter list, an arrow (->), and a body. They provide a way to define and use anonymous functions. https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 18/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech For example, consider a functional interface Runnable that represents a task to be executed. With a lambda expression, you can define and execute a runnable task as follows: Runnable task = () -> { System.out.println("Executing a runnable task."); }; task.run(); // Executes the task We will talk about a more practical example later down the post. What is the diamond problem in inheritance? The diamond problem in inheritance is a common issue in object-oriented programming languages that support multiple inheritance. It occurs when a class inherits from two classes that have a common ancestor class, resulting in ambiguity about which superclass’s method or attribute to use. Java solves the diamond problem by not supporting multiple inheritance of classes (i.e., a class cannot inherit from more than one class). However, Java allows multiple inheritance of interfaces, which doesn’t lead to the diamond problem because interfaces only declare method signatures, and the implementing class must provide concrete implementations. In case of method conflicts, the implementing class must explicitly choose which method to use. Here’s a simplified example to illustrate the diamond problem (even though Java doesn’t directly encounter it): class A { void display() { System.out.println("Class A"); } } interface B { default void display() { System.out.println("Interface B"); } } https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 19/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech interface C { default void display() { System.out.println("Interface C"); } } // This would lead to a diamond problem if Java supported multiple inheritance // class D extends B, C { } // To solve this issue in Java with interfaces, you must provide an explicit im class D implements B, C { @Override public void display() { // Choose which method to use B.super.display(); // Using B's method C.super.display(); // Using C's method } } In Java, the diamond problem is avoided through interface implementation and explicit method choice when conflicts arise. Describe the difference between fail-fast and fail-safe iterators. In Java, fail-fast and fail-safe are two strategies for handling concurrent modification of collections during iteration. Fail-fast iterators throw a ConcurrentModificationException if a collection is modified while being iterated. Fail-safe iterators, on the other hand, do not throw exceptions and allow safe iteration even if the collection is modified concurrently. Fail-Fast Iterator Example: import java.util.ArrayList; import java.util.Iterator; import java.util.List; public class FailFastExample { public static void main(String[] args) { List list = new ArrayList(); list.add("Alice"); list.add("Bob"); list.add("Charlie"); // Create an iterator https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 20/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Iterator iterator = list.iterator(); while (iterator.hasNext()) { String name = iterator.next(); System.out.println(name); // Simulate concurrent modification if (name.equals("Bob")) { list.remove(name); // This will throw ConcurrentModificationExc } } } } In this example, when we attempt to remove an element from the list while iterating, it leads to a ConcurrentModificationException, which is characteristic of fail-fast behavior. Fail-fast iterators immediately detect and throw an exception when they detect that the collection has been modified during iteration. Fail-Safe Iterator Example: import java.util.Iterator; import java.util.concurrent.ConcurrentHashMap; public class FailSafeExample { public static void main(String[] args) { ConcurrentHashMap map = new ConcurrentHashMap(); map.put(1, "One"); map.put(2, "Two"); map.put(3, "Three"); // Create an iterator Iterator iterator = map.keySet().iterator(); while (iterator.hasNext()) { Integer key = iterator.next(); System.out.println(key); // Simulate concurrent modification (no exception thrown) if (key == 2) { map.put(4, "Four"); } } } https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 21/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech } In this example, a ConcurrentHashMap is used, which supports fail-safe iterators. Even if we modify the map concurrently while iterating, there is no ConcurrentModificationException thrown. Fail-safe iterators continue iterating over the original elements and do not reflect changes made after the iterator is created. What is type erasure in Java generics? Type erasure is a process in Java where type parameters in generic classes or methods are replaced with their upper bound or Object during compilation. This erasure ensures backward compatibility with pre-generic Java code. However, it means that the type information is not available at runtime, which can lead to issues in some cases. FREE MASTERCLASS ALERT! Unlock the secrets to a lucrative Data Science career, absolutely free! As a bonus, you’ll also receive preparation material for Data Science interviews. If you’re truly passionate about elevating your Data Science career, don’t miss out on our exclusive Six Figure Data Science eBook. Dive into this comprehensive guide and take your skills to the next level. Click the link and get started today! Six Figure Data Science eBook Download Six Figure Data Science eBook downloads.tatevaslanyan.com How Can You Dive Deeper? After delving into the intricacies of Java through this article, you might be contemplating the next steps in your journey. If you’re inclined towards a structured approach to deepen your understanding, LunarTech offers just the platform. This program provides not only a thorough grasp of theoretical concepts but also an emphasis on practical application, supplemented with abundant practice resources https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 22/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech and specialized interview preparation, allowing you to progress at your own pace. This course is also a part of The Ultimate Data Science Bootcamp which has earned the recognition of being one of the Best Data Science Bootcamps of 2023, and has been featured in esteemed publications like Forbes, Yahoo, Entrepreneur and more. This is your chance to be a part of a community that thrives on innovation and knowledge. The Ultimate Data Science Bootcamp | LunarTech Become Job-ready Data Scientist with our complete bootcamp covering Statistics, Machine Learning, NLP, A/B Testing… lunartech.ai Best data science bootcamps for 2023 A list of what we believe are the best data science bootcamps around for levelling up your skills and landing a new… www.itpro.com Connect with Me: Vahe Aslanyan - Crafting Code, Shaping Futures Dive into Vahe Aslanyan's digital world, where each endeavor offers new insights and every hurdle paves the way for… www.vaheaslanyan.com Linkedin: https://www.linkedin.com/in/vahe-aslanyan/ Navigating the intricate world of software development, AI, or data science? I’m genuinely interested in your thoughts and insights. If there are aspects of this article you believe could be refined or if you have ideas on related topics, I’d truly value https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 23/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech hearing from you. Feel free to reach out directly on LinkedIn for a more in-depth conversation. Java Java Interview Questions Interview Software Development Open in app Sign up Sign in Follow Search Written by Vahe Aslanyan 321 Followers · Editor for LunarTech Studying Computer Science and experienced with top tech firms, I co-founded LunarTech to revolutionize data science education. Join us for excellence. More from Vahe Aslanyan and LunarTech Vahe Aslanyan https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 24/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech The Java Interview Prep Handbook — 50 Questions Solved + Code Examples If you’re trying to get a job in big tech or you want to refine your skills in software development, a strong grasp of Java is… Jan 10 251 3 Tatev Karen Aslanyan in LunarTech Fundamentals Of Statistics For Data Scientists and Data Analysts Key statistical concepts for your data science or data analytics journey Apr 17, 2021 2.3K 10 https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 25/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Tatev Karen Aslanyan in LunarTech Simple and Complete Guide to A/B Testing End-to-end A/B testing for your Data Science experiments for non-technical and technical specialists with examples and Python… Aug 20, 2021 1.5K 7 Vahe Aslanyan Mastering Java: A Deep Dive into Advanced Techniques and Concepts As we embark on Chapter 5, we delve into the more advanced territories of Java programming, drawing upon the foundational knowledge… https://news.lunartech.ai/cracking-java-interview-bcc73fb75be9 26/31 10/8/24, 2:43 PM Cracking Java Interview in 2024. 30 Curated Questions to Sharpen Your… | by Vahe Aslanyan | LunarTech Jan 4 17 See all from Vahe Aslanyan See all from LunarTech Recommended from Medium Ajay Rathod in Level Up Coding A Comprehensive Journey from Java 8 to Java 21 with Code Examples of Essential API Enhancements” Hello Friends, In this article I would like to talk about various versions of Java. 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