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Top 50 Java Interviews Questions | Tutort Academy - Course for Working Professional

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The document contains a curated list of important Java interview questions and answers, covering topics such as platform independence, object-oriented concepts, exception handling, and multithreading. It explains key features of Java, including JDK, JRE, JVM, and concepts like static methods, synchronization, and the Java Collections Framework. The document also highlights testimonials from students who have successfully transitioned their careers after undergoing training at Tutort Academy.

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Top 50 tutortacademy Curated by INTERVIEW QUESTIONS JAVA JAVA
tutort academy Curated by 1 2 Question Question What is Java? What is the difference between JDK, JRE, and JVM? Java is a high-level, object-oriented programming language developed by Sun Microsystems. It is known for its platform independence, as Java code can run on any platform with a Java Virtual Machine (JVM). JDK JRE JVM (Java Development Kit) is used for Java application development, (Java Runtime Environment) is used to run Java applications, and (Java Virtual Machine) executes Java bytecode. public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } // JDK contains the tools needed for development // JRE is used to run Java applications public class Main { public static void main(String[] args) { System.out.println("JDK vs. JRE"); } }
tutort academy Curated by 3 Question Explain the main features of Java. Java features include platform independence, object-oriented, robust, secure, multithreaded, and high-performance. // Example of platform independence public class PlatformIndependent { public static void main(String[] args) { System.out.println("Hello, World!"); } } Courses Offered by Tutort Academy Full Stack Data Science (AI & ML) Data Science & Machine Learning Learn more Learn more Full Stack with MERN Learn more DSA with System Design Learn more
tutort academy Curated by 4 Question What are the differences between abstract classes and interfaces? Abstract classes can have constructors, fields, and method implementations, while interfaces only define method signatures. A class can extend only one abstract class but implement multiple interfaces. abstract class Animal { String name;   Animal(String name) { this.name = name; }   abstract void sound(); }   interface Flyable { void fly(); } Subhadip Chowdhury From To Placed with 100% Hike Subhadip Chowdhury From To Placed with 100% Hike
tutort academy Curated by 5 6 Question Question How does Java achieve platform independence? Explain the 'final' keyword in Java. Java achieves platform independence by compiling source code into bytecode, which is then executed by the JVM specific to the platform. The 'final' keyword is used to declare variables, methods, or classes as unchangeable. A 'final' variable cannot be reassigned, a 'final' method cannot be overridden, and a 'final' class cannot be extended. // Java source code public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } final class FinalClass { final int constantValue = 42;   final void doSomething() { // Implementation } }
tutort academy Curated by 7 Question 8 Question What is the difference between 'equals()' and '==' in Java? What is a constructor, and why is it used in Java? '==' compares object references, while 'equals()' compares the content (values) of objects. You can override 'equals()' to provide custom comparison logic. A constructor is a special method used to initialize objects. It is called when an object is created and ensures that the object is in a valid state. String str1 = new String("Hello"); String str2 = new String("Hello");   boolean referenceComparison = (str1 == str2); // false (different objects) boolean contentComparison = str1.equals(str2); // true (same content) class Person { String name;   // Constructor Person(String name) { this.name = name; } }
tutort academy Curated by 9 10 Question Question What is the 'this' keyword in Java? Explain method overloading and method overriding in Java. 'this' refers to the current object within a class. It is often used to distinguish between instance variables and method parameters with the same name. Method overloading is when multiple methods in the same class have the same name but different parameters. Method overriding occurs when a subclass provides a specific implementation for a method defined in its superclass. class MyClass { int value; MyClass(int value) { this.value = value; // 'this' refers to the instance variable } } class MathOperations { int add(int a, int b) { return a + b; } double add(double a, double b) { return a + b; } }
tutort academy Curated by 11 12 Question Question What is a static method and when is it used? What is the 'super' keyword in Java? A static method belongs to the class rather than an instance. It can be called using the class name and is often used for utility functions that don't require instance-specific data. 'super' is used to call a superclass's constructor or refer to a superclass's method or variable in the context of method overriding. class MathUtils { static int add(int a, int b) { return a + b; } } class Parent { void show() { System.out.println("Parent class"); } } class Child extends Parent { void show() { super.show(); // Calls the parent's 'show' method System.out.println("Child class"); } }
tutort academy Curated by 13 6 Question Explain the 'try-catch-finally' block in Java for exception handling. 'try' is used to enclose code that might throw an exception, 'catch' is used to handle exceptions, and 'finally' is used to specify code that will always execute, whether an exception occurs or not. try { // Code that might throw an exception int result = 10 / 0; } catch (ArithmeticException e) { // Handle the exception System.out.println("Error: " + e.getMessage()); } finally { // Cleanup code (always executed) System.out.println("Cleanup code"); } So far, the best course. This was the best decision I've ever made. When I started, I knew the very basics of simple data structures, but after finishing the course, I was confident that I could solve most problems. Because of Tutort Academy I am working with top tech company AMD. Sweta Verma
tutort academy Curated by 14 6 Question What is the difference between checked and unchecked exceptions? Checked exceptions are checked at compile-time and must be either caught or declared in the method signature using 'throws.' Unchecked exceptions (RuntimeExceptions) are not checked at compile-time. // Checked exception (must be handled or declared) try { FileInputStream file = new FileInputStream("file.txt"); } catch (FileNotFoundException e) { System.out.println("File not found."); } // Unchecked exception (no need to declare or catch) int result = 10 / 0; // ArithmeticException Avishkar Dalvi From To Placed with 245% Hike Avishkar Dalvi From To Placed with 245% Hike
tutort academy Curated by 15 Question Describe the 'NullPointerException' and how to prevent it. 'NullPointerException' occurs when trying to access methods or fields of a null object. To prevent it, ensure that object references are not null before accessing them. String name = null; if (name != null) { int length = name.length(); // Check for null before accessing } Guaranteed Job Referrals Highest CTC 100% Hiring Partners 250+ 2.1CR Why Tutort Academy? I got rejected in the Amazon interview. After that, I joined Tutort Academy for DSA concepts as a working professional. They fulfilled my all requirements and that is why I am in Microsoft right now. I highly recommend Tutort Academy for professionals. When I started looking for a software development course, I found Tutort Academy completely matching my requirements. Apart from the content and live classes that they provide, the mentorship program is the cherry on the cake. Akansha Likhdhari Nikesh Bisen
tutort academy Curated by 16 6 Question What is the purpose of the 'finally' block in exception handling? The 'finally' block is used to ensure that essential cleanup code executes, such as closing files or releasing resources, regardless of whether an exception occurs or not. FileInputStream file = null; try { file = new FileInputStream("file.txt"); // Code to read the file } catch (IOException e) { System.out.println("Error reading the file."); } finally { // Close the file, even if an exception occurs try { if (file != null) { file.close(); } } catch (IOException e) { System.out.println("Error closing the file."); } } Sivani yadav From To Switch from Service Based Company Sivani yadav From To Switch from Service Based Company
tutort academy Curated by 17 6 Question What is the Java Collections Framework, and why is it important? The Java Collections Framework provides a set of classes and interfaces for working with collections of objects. It's essential for efficient data manipulation and storage in Java applications. // Example of using ArrayList from the Collections Framework import java.util.ArrayList; import java.util.List; public class CollectionExample { public static void main(String[] args) { List<String> names = new ArrayList<>(); names.add("Alice"); names.add("Bob"); names.add("Charlie"); System.out.println(names); } } Ammar Shareef From To Placed with 100% Hike Ammar Shareef From To Placed with 100% Hike
tutort academy Curated by 18 6 Question Explain the difference between ArrayList and LinkedList. ArrayList is a dynamic array that allows fast random access, while LinkedList is a doubly-linked list that is better suited for frequent insertions and deletions. import java.util.ArrayList; import java.util.LinkedList; import java.util.List; public class ListExample { public static void main(String[] args) { List<String> arrayList = new ArrayList<>(); List<String> linkedList = new LinkedList<>();   // ArrayList is good for random access arrayList.add("A"); arrayList.add("B"); arrayList.add("C"); System.out.println(arrayList.get(1)); // Output: B   // LinkedList is good for insertions and deletions linkedList.add("X"); linkedList.add("Y"); linkedList.add("Z"); linkedList.remove(1); // Removes "Y" } }
tutort academy Curated by 19 Question What is the 'hashCode()' method used for in Java? 'hashCode()' is used to calculate the hash code of an object, primarily used in data structures like HashMap and HashSet for efficient storage and retrieval. class Student { String name; int id;   // Override hashCode() method @Override public int hashCode() { return Objects.hash(name, id); } } Tutort Benefits 24x7 Live 1:1 Video based doubt support 1:1 Mentorship from Industry experts Resume building & Mock Interview Preparations Special support for foreign students
tutort academy Curated by 20 Question How does Java handle multiple threads, and what are the potential issues with multithreading? Java supports multithreading through the 'Thread' class and the 'Runnable' interface. Potential issues include race conditions, deadlocks, and thread interference, which must be managed using synchronization. class MyThread extends Thread { public void run() { // Thread's logic } } class MyRunnable implements Runnable { public void run() { // Runnable's logic } } Vikhil Krishna From To Switch from Service Based Company Vikhil Krishna From To Switch from Service Based Company
tutort academy Curated by 21 6 Question What is synchronization in Java, and how is it achieved? Synchronization is used to ensure that only one thread accesses a block of code or a method at a time. It can be achieved using the 'synchronized' keyword or by using synchronized blocks. class SynchronizedExample { private int count = 0;   // Synchronized method synchronized void increment() { count++; }   // Synchronized block void performTask() { synchronized (this) { // Code that needs synchronization } } }
tutort academy Curated by 22 23 Question Question Explain the 'volatile' keyword in Java. What is the 'thread-safe' concept in Java, and how can you make a class thread-safe? 'volatile' is used to declare a variable as "volatile," meaning its value can be modified by multiple threads. It ensures that the variable's value is always read from and written to the main memory, avoiding thread caching. A thread-safe class ensures that its methods can be safely used by multiple threads without causing data corruption or inconsistencies. You can make a class thread-safe by using synchronization, locks, or concurrent data structures. class SharedResource { volatile int value = 0; } import java.util.concurrent.atomic.AtomicInteger; class Counter { private AtomicInteger count = new AtomicInteger(0);   // Thread-safe increment void increment() { count.incrementAndGet(); } }
tutort academy Curated by 24 6 Question Explain the 'wait' and 'notify' methods in Java for thread synchronization. 'wait' is used to make a thread pause execution until another thread invokes 'notify' or 'notifyAll' on the same object, waking up the waiting thread(s). class SharedResource { synchronized void produce() { // Produce some data notify(); // Notify waiting threads }   synchronized void consume() throws InterruptedException { wait(); // Wait for data to be available // Consume the data } } Saumya Mishra From To Switch from Service Based Company Saumya Mishra From To Switch from Service Based Company
tutort academy Curated by 25 26 Question Question What is the Java Memory Model (JMM), and how does it relate to multithreading? What is the 'garbage collection' in Java, and how does it work? JMM defines how threads interact with memory and how changes to variables are visible to other threads. It ensures that the JVM respects the memory visibility guarantees. Answer: Garbage collection is the automatic process of identifying and reclaiming memory occupied by objects that are no longer referenced. Java uses different garbage collection algorithms like generational, mark-and-sweep, and G1. class SharedResource { private volatile int value = 0; void increment() { value++; } int getValue() { return value; } } class MyClass { // Object creation public void createObject() { SomeObject obj = new SomeObject(); // obj goes out of scope and becomes eligible for garbage collection } }
tutort academy Curated by 27 28 Question Question Explain the 'finalize()' method in Java. What is the purpose of the 'assert' statement in Java ? 'finalize()' is a method called by the garbage collector before an object is reclaimed. It allows you to perform cleanup operations on resources like files or sockets. The 'assert' statement is used to test assumptions about program behavior. It throws an AssertionError if the condition specified is false. class Resource { // Clean up resources in the finalize() method protected void finalize() { // Close files, release resources, etc. } } int value = 10; assert value > 0 : "Value must be positive"; // Throws AssertionError if false
tutort academy Curated by 29 30 Question Question Describe the 'enum' type in Java and its advantages. What is the 'autoboxing' and 'unboxing' feature in Java? An 'enum' is a special data type that defines a set of constant values. It provides type safety, readability, and can be used in switch statements. Autoboxing is the automatic conversion of a primitive type to its corresponding wrapper class, and unboxing is the reverse process. For example, converting 'int' to 'Integer' and vice versa. enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY } Integer num = 42; // Autoboxing int value = num; // Unboxing
tutort academy Curated by 31 32 Question Question What are Java annotations, and how are they used? Explain the 'try-with-resources' statement in Java for resource management. Annotations provide metadata about the code and can be used to add information to classes, methods, or variables. They are commonly used for configuration, documentation, and code generation. 'try-with-resources' is used to automatically close resources like files, sockets, or database connections when they are no longer needed. It simplifies resource management and prevents resource leaks. @Override public void performTask() { // Method implementation } @Deprecated public void oldMethod() { // Deprecated method } try (FileInputStream file = new FileInputStream("file.txt")) { // Read and process the file } catch (IOException e) { // Handle exceptions }
tutort academy Curated by 33 34 Question Question How does Java support functional programming, and what are lambda expressions? What is the 'Stream' API in Java, and how is it used for data manipulation? Java supports functional programming through lambda expressions, which allow you to define and pass functions as arguments to methods. They are used for writing more concise and expressive code. The 'Stream' API is used for processing sequences of data in a functional style. It provides methods for filtering, mapping, reducing, and collecting data efficiently. // Using a lambda expression to define a function Function<Integer, Integer> square = (x) -> x * x; int result = square.apply(5); // Result is 25 List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); int sum = numbers.stream() .filter(n -> n % 2 == 0) .mapToInt(Integer::intValue) .sum();
tutort academy Curated by 35 36 Question Question Explain the 'Optional' class in Java and its purpose. What is the 'StringBuilder' class, and how does it differ from 'String'? 'Optional' is a container class that can contain either a non-null value or be empty. It is used to avoid null pointer exceptions and indicate that a value may or may not be present. 'StringBuilder' is a mutable sequence of characters, while 'String' is immutable. 'StringBuilder' is used for efficient string manipulation without creating new objects. Optional<String> optionalName = Optional.ofNullable(getName()); String result = optionalName.orElse("Default Name"); StringBuilder sb = new StringBuilder(); sb.append("Hello, "); sb.append("World!"); String result = sb.toString(); // "Hello, World!"
tutort academy Curated by 37 38 Question Question What is a Java annotation processor, and how does it work? What is serialization in Java, and how is it implemented? An annotation processor is a tool that reads and processes annotations at compile-time. It can generate code, perform validation, or enhance classes based on annotations. Serialization is the process of converting an object into a stream of bytes to store it or transmit it over a network. It is implemented by making a class implement the 'Serializable' interface. @MyAnnotation public class MyClass { // Annotation-processed code } class Student implements Serializable { String name; int rollNumber; // ... }
tutort academy Curated by 39 40 Question Question Explain the 'Reflection' API in Java. What is the difference between an 'inner class' and a 'nested class'? The 'Reflection' API allows you to inspect and manipulate classes, methods, fields, and objects at runtime. It is often used for dynamic code generation and testing. An inner class is a non-static class defined within another class, while a nested class is any class defined within another class. Inner classes have access to the enclosing class's members. Class<?> clazz = Class.forName("com.example.MyClass"); Field[] fields = clazz.getDeclaredFields(); // Use reflection to inspect or modify fields/ methods class Outer { int outerValue;   class Inner { int innerValue = outerValue; } }
tutort academy Curated by 41 42 Question Question What is the 'Executor' framework in Java, and how does it simplify thread management? What are the 'Comparable' and 'Comparator' interfaces, and when are they used? The 'Executor' framework provides a higher-level abstraction for managing threads. It decouples the task submission from the thread creation and management, making it easier to control thread execution. 'Comparable' is used to define the natural ordering of objects within a class, while 'Comparator' allows you to define custom comparison logic for classes not under your control. Executor executor = Executors.newFixedThreadPool(2); executor.execute(() -> System.out.println("Task executed.")); class Student implements Comparable<Student> { String name; int rollNumber; @Override public int compareTo(Student other) { return this.rollNumber - other.rollNumber; } }
tutort academy Curated by 43 44 Question Question Explain the 'fork-join' framework in Java for parallel processing. What is 'Project Loom,' and how does it impact Java's concurrency model? The 'fork-join' framework is used for parallelism in Java, particularly for divide-and-conquer algorithms. It uses a pool of worker threads to execute tasks concurrently. Project Loom aims to simplify and improve concurrency in Java by introducing lightweight, user-mode threads called 'Fibers.' It promises more efficient and scalable concurrency. ForkJoinPool pool = new ForkJoinPool(); long result = pool.invoke(new MyRecursiveTask(1, 1000)); import java.util.concurrent.Executors; import java.util.concurrent.ExecutorService; import java.util.concurrent.ForkJoinPool; import java.util.concurrent.Future;   public class FiberExample { public static void main(String[] args) { ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor(); Future<String> future = executor.submit(() -> "Hello from a Fiber!"); } }
tutort academy Curated by 45 46 Question Question What is 'Project Valhalla,' and how does it aim to enhance Java's performance? Explain 'Project Panama' and how it improves Java's interaction with native code. Project Valhalla aims to introduce value types and reified generics to Java, improving memory efficiency and performance for certain data structures. Project Panama focuses on improving the connection between Java and native code, making it easier to interoperate with libraries written in other languages like C and C++. value class Point { int x; int y; } // Example of Java Native Interface (JNI) with native C code public class NativeExample { native void nativeMethod(); }
tutort academy Curated by 47 48 49 Question Question Question What is 'Project Metropolis,' and how does it aim to improve Java's memory management and performance? What is 'Project Valhalla,' and how does it aim to enhance Java's performance? What is 'Project Panama,' and how does it improve Java's interaction with native code? As of my last update in September 2021, Project Metropolis was not a well- known project. Please refer to the latest Java documentation or resources for any updates regarding this project. Project Valhalla aims to introduce value types and reified generics to Java, improving memory efficiency and performance for certain data structures. Project Panama focuses on improving the connection between Java and native code, making it easier to interoperate with libraries written in other languages like C and C++.
tutort academy Curated by 50 Question How does 'Project Metropolis' aim to improve Java's memory management and performance? As of my last update in September 2021, Project Metropolis was not a well- known project. Please refer to the latest Java documentation or resources for any updates regarding this project. Guaranteed Job Referrals Highest CTC 100% Hiring Partners 250+ 2.1CR Why Tutort Academy? I took the Advanced DSA Course at Tutort Academy. Nishant Sir's explanation of the concepts was excellent. I thoroughly enjoyed the course. The course is also valid for a lifetime, and new material is added regularly. With their help, I cracked many top product based companies & currently working with Zest Money. Gopal Yadav
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Top 50 Java Interviews Questions | Tutort Academy - Course for Working Professional

  • 2. tutort academy Curated by 1 2 Question Question What is Java? What is the difference between JDK, JRE, and JVM? Java is a high-level, object-oriented programming language developed by Sun Microsystems. It is known for its platform independence, as Java code can run on any platform with a Java Virtual Machine (JVM). JDK JRE JVM (Java Development Kit) is used for Java application development, (Java Runtime Environment) is used to run Java applications, and (Java Virtual Machine) executes Java bytecode. public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } // JDK contains the tools needed for development // JRE is used to run Java applications public class Main { public static void main(String[] args) { System.out.println("JDK vs. JRE"); } }
  • 3. tutort academy Curated by 3 Question Explain the main features of Java. Java features include platform independence, object-oriented, robust, secure, multithreaded, and high-performance. // Example of platform independence public class PlatformIndependent { public static void main(String[] args) { System.out.println("Hello, World!"); } } Courses Offered by Tutort Academy Full Stack Data Science (AI & ML) Data Science & Machine Learning Learn more Learn more Full Stack with MERN Learn more DSA with System Design Learn more
  • 4. tutort academy Curated by 4 Question What are the differences between abstract classes and interfaces? Abstract classes can have constructors, fields, and method implementations, while interfaces only define method signatures. A class can extend only one abstract class but implement multiple interfaces. abstract class Animal { String name;   Animal(String name) { this.name = name; }   abstract void sound(); }   interface Flyable { void fly(); } Subhadip Chowdhury From To Placed with 100% Hike Subhadip Chowdhury From To Placed with 100% Hike
  • 5. tutort academy Curated by 5 6 Question Question How does Java achieve platform independence? Explain the 'final' keyword in Java. Java achieves platform independence by compiling source code into bytecode, which is then executed by the JVM specific to the platform. The 'final' keyword is used to declare variables, methods, or classes as unchangeable. A 'final' variable cannot be reassigned, a 'final' method cannot be overridden, and a 'final' class cannot be extended. // Java source code public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } final class FinalClass { final int constantValue = 42;   final void doSomething() { // Implementation } }
  • 6. tutort academy Curated by 7 Question 8 Question What is the difference between 'equals()' and '==' in Java? What is a constructor, and why is it used in Java? '==' compares object references, while 'equals()' compares the content (values) of objects. You can override 'equals()' to provide custom comparison logic. A constructor is a special method used to initialize objects. It is called when an object is created and ensures that the object is in a valid state. String str1 = new String("Hello"); String str2 = new String("Hello");   boolean referenceComparison = (str1 == str2); // false (different objects) boolean contentComparison = str1.equals(str2); // true (same content) class Person { String name;   // Constructor Person(String name) { this.name = name; } }
  • 7. tutort academy Curated by 9 10 Question Question What is the 'this' keyword in Java? Explain method overloading and method overriding in Java. 'this' refers to the current object within a class. It is often used to distinguish between instance variables and method parameters with the same name. Method overloading is when multiple methods in the same class have the same name but different parameters. Method overriding occurs when a subclass provides a specific implementation for a method defined in its superclass. class MyClass { int value; MyClass(int value) { this.value = value; // 'this' refers to the instance variable } } class MathOperations { int add(int a, int b) { return a + b; } double add(double a, double b) { return a + b; } }
  • 8. tutort academy Curated by 11 12 Question Question What is a static method and when is it used? What is the 'super' keyword in Java? A static method belongs to the class rather than an instance. It can be called using the class name and is often used for utility functions that don't require instance-specific data. 'super' is used to call a superclass's constructor or refer to a superclass's method or variable in the context of method overriding. class MathUtils { static int add(int a, int b) { return a + b; } } class Parent { void show() { System.out.println("Parent class"); } } class Child extends Parent { void show() { super.show(); // Calls the parent's 'show' method System.out.println("Child class"); } }
  • 9. tutort academy Curated by 13 6 Question Explain the 'try-catch-finally' block in Java for exception handling. 'try' is used to enclose code that might throw an exception, 'catch' is used to handle exceptions, and 'finally' is used to specify code that will always execute, whether an exception occurs or not. try { // Code that might throw an exception int result = 10 / 0; } catch (ArithmeticException e) { // Handle the exception System.out.println("Error: " + e.getMessage()); } finally { // Cleanup code (always executed) System.out.println("Cleanup code"); } So far, the best course. This was the best decision I've ever made. When I started, I knew the very basics of simple data structures, but after finishing the course, I was confident that I could solve most problems. Because of Tutort Academy I am working with top tech company AMD. Sweta Verma
  • 10. tutort academy Curated by 14 6 Question What is the difference between checked and unchecked exceptions? Checked exceptions are checked at compile-time and must be either caught or declared in the method signature using 'throws.' Unchecked exceptions (RuntimeExceptions) are not checked at compile-time. // Checked exception (must be handled or declared) try { FileInputStream file = new FileInputStream("file.txt"); } catch (FileNotFoundException e) { System.out.println("File not found."); } // Unchecked exception (no need to declare or catch) int result = 10 / 0; // ArithmeticException Avishkar Dalvi From To Placed with 245% Hike Avishkar Dalvi From To Placed with 245% Hike
  • 11. tutort academy Curated by 15 Question Describe the 'NullPointerException' and how to prevent it. 'NullPointerException' occurs when trying to access methods or fields of a null object. To prevent it, ensure that object references are not null before accessing them. String name = null; if (name != null) { int length = name.length(); // Check for null before accessing } Guaranteed Job Referrals Highest CTC 100% Hiring Partners 250+ 2.1CR Why Tutort Academy? I got rejected in the Amazon interview. After that, I joined Tutort Academy for DSA concepts as a working professional. They fulfilled my all requirements and that is why I am in Microsoft right now. I highly recommend Tutort Academy for professionals. When I started looking for a software development course, I found Tutort Academy completely matching my requirements. Apart from the content and live classes that they provide, the mentorship program is the cherry on the cake. Akansha Likhdhari Nikesh Bisen
  • 12. tutort academy Curated by 16 6 Question What is the purpose of the 'finally' block in exception handling? The 'finally' block is used to ensure that essential cleanup code executes, such as closing files or releasing resources, regardless of whether an exception occurs or not. FileInputStream file = null; try { file = new FileInputStream("file.txt"); // Code to read the file } catch (IOException e) { System.out.println("Error reading the file."); } finally { // Close the file, even if an exception occurs try { if (file != null) { file.close(); } } catch (IOException e) { System.out.println("Error closing the file."); } } Sivani yadav From To Switch from Service Based Company Sivani yadav From To Switch from Service Based Company
  • 13. tutort academy Curated by 17 6 Question What is the Java Collections Framework, and why is it important? The Java Collections Framework provides a set of classes and interfaces for working with collections of objects. It's essential for efficient data manipulation and storage in Java applications. // Example of using ArrayList from the Collections Framework import java.util.ArrayList; import java.util.List; public class CollectionExample { public static void main(String[] args) { List<String> names = new ArrayList<>(); names.add("Alice"); names.add("Bob"); names.add("Charlie"); System.out.println(names); } } Ammar Shareef From To Placed with 100% Hike Ammar Shareef From To Placed with 100% Hike
  • 14. tutort academy Curated by 18 6 Question Explain the difference between ArrayList and LinkedList. ArrayList is a dynamic array that allows fast random access, while LinkedList is a doubly-linked list that is better suited for frequent insertions and deletions. import java.util.ArrayList; import java.util.LinkedList; import java.util.List; public class ListExample { public static void main(String[] args) { List<String> arrayList = new ArrayList<>(); List<String> linkedList = new LinkedList<>();   // ArrayList is good for random access arrayList.add("A"); arrayList.add("B"); arrayList.add("C"); System.out.println(arrayList.get(1)); // Output: B   // LinkedList is good for insertions and deletions linkedList.add("X"); linkedList.add("Y"); linkedList.add("Z"); linkedList.remove(1); // Removes "Y" } }
  • 15. tutort academy Curated by 19 Question What is the 'hashCode()' method used for in Java? 'hashCode()' is used to calculate the hash code of an object, primarily used in data structures like HashMap and HashSet for efficient storage and retrieval. class Student { String name; int id;   // Override hashCode() method @Override public int hashCode() { return Objects.hash(name, id); } } Tutort Benefits 24x7 Live 1:1 Video based doubt support 1:1 Mentorship from Industry experts Resume building & Mock Interview Preparations Special support for foreign students
  • 16. tutort academy Curated by 20 Question How does Java handle multiple threads, and what are the potential issues with multithreading? Java supports multithreading through the 'Thread' class and the 'Runnable' interface. Potential issues include race conditions, deadlocks, and thread interference, which must be managed using synchronization. class MyThread extends Thread { public void run() { // Thread's logic } } class MyRunnable implements Runnable { public void run() { // Runnable's logic } } Vikhil Krishna From To Switch from Service Based Company Vikhil Krishna From To Switch from Service Based Company
  • 17. tutort academy Curated by 21 6 Question What is synchronization in Java, and how is it achieved? Synchronization is used to ensure that only one thread accesses a block of code or a method at a time. It can be achieved using the 'synchronized' keyword or by using synchronized blocks. class SynchronizedExample { private int count = 0;   // Synchronized method synchronized void increment() { count++; }   // Synchronized block void performTask() { synchronized (this) { // Code that needs synchronization } } }
  • 18. tutort academy Curated by 22 23 Question Question Explain the 'volatile' keyword in Java. What is the 'thread-safe' concept in Java, and how can you make a class thread-safe? 'volatile' is used to declare a variable as "volatile," meaning its value can be modified by multiple threads. It ensures that the variable's value is always read from and written to the main memory, avoiding thread caching. A thread-safe class ensures that its methods can be safely used by multiple threads without causing data corruption or inconsistencies. You can make a class thread-safe by using synchronization, locks, or concurrent data structures. class SharedResource { volatile int value = 0; } import java.util.concurrent.atomic.AtomicInteger; class Counter { private AtomicInteger count = new AtomicInteger(0);   // Thread-safe increment void increment() { count.incrementAndGet(); } }
  • 19. tutort academy Curated by 24 6 Question Explain the 'wait' and 'notify' methods in Java for thread synchronization. 'wait' is used to make a thread pause execution until another thread invokes 'notify' or 'notifyAll' on the same object, waking up the waiting thread(s). class SharedResource { synchronized void produce() { // Produce some data notify(); // Notify waiting threads }   synchronized void consume() throws InterruptedException { wait(); // Wait for data to be available // Consume the data } } Saumya Mishra From To Switch from Service Based Company Saumya Mishra From To Switch from Service Based Company
  • 20. tutort academy Curated by 25 26 Question Question What is the Java Memory Model (JMM), and how does it relate to multithreading? What is the 'garbage collection' in Java, and how does it work? JMM defines how threads interact with memory and how changes to variables are visible to other threads. It ensures that the JVM respects the memory visibility guarantees. Answer: Garbage collection is the automatic process of identifying and reclaiming memory occupied by objects that are no longer referenced. Java uses different garbage collection algorithms like generational, mark-and-sweep, and G1. class SharedResource { private volatile int value = 0; void increment() { value++; } int getValue() { return value; } } class MyClass { // Object creation public void createObject() { SomeObject obj = new SomeObject(); // obj goes out of scope and becomes eligible for garbage collection } }
  • 21. tutort academy Curated by 27 28 Question Question Explain the 'finalize()' method in Java. What is the purpose of the 'assert' statement in Java ? 'finalize()' is a method called by the garbage collector before an object is reclaimed. It allows you to perform cleanup operations on resources like files or sockets. The 'assert' statement is used to test assumptions about program behavior. It throws an AssertionError if the condition specified is false. class Resource { // Clean up resources in the finalize() method protected void finalize() { // Close files, release resources, etc. } } int value = 10; assert value > 0 : "Value must be positive"; // Throws AssertionError if false
  • 22. tutort academy Curated by 29 30 Question Question Describe the 'enum' type in Java and its advantages. What is the 'autoboxing' and 'unboxing' feature in Java? An 'enum' is a special data type that defines a set of constant values. It provides type safety, readability, and can be used in switch statements. Autoboxing is the automatic conversion of a primitive type to its corresponding wrapper class, and unboxing is the reverse process. For example, converting 'int' to 'Integer' and vice versa. enum Day { SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY } Integer num = 42; // Autoboxing int value = num; // Unboxing
  • 23. tutort academy Curated by 31 32 Question Question What are Java annotations, and how are they used? Explain the 'try-with-resources' statement in Java for resource management. Annotations provide metadata about the code and can be used to add information to classes, methods, or variables. They are commonly used for configuration, documentation, and code generation. 'try-with-resources' is used to automatically close resources like files, sockets, or database connections when they are no longer needed. It simplifies resource management and prevents resource leaks. @Override public void performTask() { // Method implementation } @Deprecated public void oldMethod() { // Deprecated method } try (FileInputStream file = new FileInputStream("file.txt")) { // Read and process the file } catch (IOException e) { // Handle exceptions }
  • 24. tutort academy Curated by 33 34 Question Question How does Java support functional programming, and what are lambda expressions? What is the 'Stream' API in Java, and how is it used for data manipulation? Java supports functional programming through lambda expressions, which allow you to define and pass functions as arguments to methods. They are used for writing more concise and expressive code. The 'Stream' API is used for processing sequences of data in a functional style. It provides methods for filtering, mapping, reducing, and collecting data efficiently. // Using a lambda expression to define a function Function<Integer, Integer> square = (x) -> x * x; int result = square.apply(5); // Result is 25 List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); int sum = numbers.stream() .filter(n -> n % 2 == 0) .mapToInt(Integer::intValue) .sum();
  • 25. tutort academy Curated by 35 36 Question Question Explain the 'Optional' class in Java and its purpose. What is the 'StringBuilder' class, and how does it differ from 'String'? 'Optional' is a container class that can contain either a non-null value or be empty. It is used to avoid null pointer exceptions and indicate that a value may or may not be present. 'StringBuilder' is a mutable sequence of characters, while 'String' is immutable. 'StringBuilder' is used for efficient string manipulation without creating new objects. Optional<String> optionalName = Optional.ofNullable(getName()); String result = optionalName.orElse("Default Name"); StringBuilder sb = new StringBuilder(); sb.append("Hello, "); sb.append("World!"); String result = sb.toString(); // "Hello, World!"
  • 26. tutort academy Curated by 37 38 Question Question What is a Java annotation processor, and how does it work? What is serialization in Java, and how is it implemented? An annotation processor is a tool that reads and processes annotations at compile-time. It can generate code, perform validation, or enhance classes based on annotations. Serialization is the process of converting an object into a stream of bytes to store it or transmit it over a network. It is implemented by making a class implement the 'Serializable' interface. @MyAnnotation public class MyClass { // Annotation-processed code } class Student implements Serializable { String name; int rollNumber; // ... }
  • 27. tutort academy Curated by 39 40 Question Question Explain the 'Reflection' API in Java. What is the difference between an 'inner class' and a 'nested class'? The 'Reflection' API allows you to inspect and manipulate classes, methods, fields, and objects at runtime. It is often used for dynamic code generation and testing. An inner class is a non-static class defined within another class, while a nested class is any class defined within another class. Inner classes have access to the enclosing class's members. Class<?> clazz = Class.forName("com.example.MyClass"); Field[] fields = clazz.getDeclaredFields(); // Use reflection to inspect or modify fields/ methods class Outer { int outerValue;   class Inner { int innerValue = outerValue; } }
  • 28. tutort academy Curated by 41 42 Question Question What is the 'Executor' framework in Java, and how does it simplify thread management? What are the 'Comparable' and 'Comparator' interfaces, and when are they used? The 'Executor' framework provides a higher-level abstraction for managing threads. It decouples the task submission from the thread creation and management, making it easier to control thread execution. 'Comparable' is used to define the natural ordering of objects within a class, while 'Comparator' allows you to define custom comparison logic for classes not under your control. Executor executor = Executors.newFixedThreadPool(2); executor.execute(() -> System.out.println("Task executed.")); class Student implements Comparable<Student> { String name; int rollNumber; @Override public int compareTo(Student other) { return this.rollNumber - other.rollNumber; } }
  • 29. tutort academy Curated by 43 44 Question Question Explain the 'fork-join' framework in Java for parallel processing. What is 'Project Loom,' and how does it impact Java's concurrency model? The 'fork-join' framework is used for parallelism in Java, particularly for divide-and-conquer algorithms. It uses a pool of worker threads to execute tasks concurrently. Project Loom aims to simplify and improve concurrency in Java by introducing lightweight, user-mode threads called 'Fibers.' It promises more efficient and scalable concurrency. ForkJoinPool pool = new ForkJoinPool(); long result = pool.invoke(new MyRecursiveTask(1, 1000)); import java.util.concurrent.Executors; import java.util.concurrent.ExecutorService; import java.util.concurrent.ForkJoinPool; import java.util.concurrent.Future;   public class FiberExample { public static void main(String[] args) { ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor(); Future<String> future = executor.submit(() -> "Hello from a Fiber!"); } }
  • 30. tutort academy Curated by 45 46 Question Question What is 'Project Valhalla,' and how does it aim to enhance Java's performance? Explain 'Project Panama' and how it improves Java's interaction with native code. Project Valhalla aims to introduce value types and reified generics to Java, improving memory efficiency and performance for certain data structures. Project Panama focuses on improving the connection between Java and native code, making it easier to interoperate with libraries written in other languages like C and C++. value class Point { int x; int y; } // Example of Java Native Interface (JNI) with native C code public class NativeExample { native void nativeMethod(); }
  • 31. tutort academy Curated by 47 48 49 Question Question Question What is 'Project Metropolis,' and how does it aim to improve Java's memory management and performance? What is 'Project Valhalla,' and how does it aim to enhance Java's performance? What is 'Project Panama,' and how does it improve Java's interaction with native code? As of my last update in September 2021, Project Metropolis was not a well- known project. Please refer to the latest Java documentation or resources for any updates regarding this project. Project Valhalla aims to introduce value types and reified generics to Java, improving memory efficiency and performance for certain data structures. Project Panama focuses on improving the connection between Java and native code, making it easier to interoperate with libraries written in other languages like C and C++.
  • 32. tutort academy Curated by 50 Question How does 'Project Metropolis' aim to improve Java's memory management and performance? As of my last update in September 2021, Project Metropolis was not a well- known project. Please refer to the latest Java documentation or resources for any updates regarding this project. Guaranteed Job Referrals Highest CTC 100% Hiring Partners 250+ 2.1CR Why Tutort Academy? I took the Advanced DSA Course at Tutort Academy. Nishant Sir's explanation of the concepts was excellent. I thoroughly enjoyed the course. The course is also valid for a lifetime, and new material is added regularly. With their help, I cracked many top product based companies & currently working with Zest Money. Gopal Yadav
  • 33. www.tutort.net Explore More Explore our courses Follow us on Watch us on Youtube Read more on Quora StartYour Upskillingwithus Advanced DSA & System Design Course Full Stack Specialisation in Software Development