- What is JVM Architecture?Answer: JVM architecture consists of ClassLoader, Runtime Data Areas (Heap, Stack, Method Area), Execution Engine, and Native Interface. It loads class files, manages memory, and executes bytecode.
- What is ClassLoader?Answer: ClassLoader loads .class files into JVM memory. Types include Bootstrap, Extension, and Application ClassLoader.
- What is Method Area?Answer: Method Area stores class metadata, static variables, and method information.
- What is Program Counter Register?Answer: It stores the address of the currently executing instruction.
- What is JIT Compiler?Answer: JIT compiler converts bytecode into native machine code to improve performance.
- What is Platform Independent feature?Answer: Java is platform independent because bytecode runs on JVM regardless of OS.
- What is Platform Dependent feature?Answer: Platform dependent programs run only on specific operating systems.
- What is Native Method?Answer: Native methods are written in other languages like C or C++ and accessed in Java.
- What is JNI?Answer: JNI (Java Native Interface) allows Java to interact with native applications.
- What is Bytecode Verifier?Answer: It checks bytecode for security violations.
- What is Class?Answer: Class is a blueprint used to create objects.
- What is Object?Answer: Object is an instance of a class.
- What is Instance Variable?Answer: Instance variable belongs to object and stored in heap memory.
- What is Local Variable?Answer: Local variables are declared inside methods.
- What is Static Variable?Answer: Static variable belongs to class and shared among all objects.
- What is Static Method?Answer: Static methods belong to class and can be called without object.
- What is Instance Method?Answer: Instance method belongs to object.
- What is Method Signature?Answer: Method signature includes method name and parameter list.
- What is Constructor Overloading?Answer: Multiple constructors with different parameters.
- What is Default Constructor?Answer: Constructor provided automatically by compiler if not defined.
- What is Parameterized Constructor?Answer: Constructor with parameters.
- What is Copy Constructor?Answer: Constructor that copies another object.
- What is Access Modifier?Answer: Defines visibility (public, private, protected, default).
- What is Public Modifier?Answer: Accessible everywhere.
- What is Private Modifier?Answer: Accessible only within class.
- What is Protected Modifier?Answer: Accessible within package and subclasses.
- What is Default Modifier?Answer: Accessible within same package.
- What is Encapsulation?Answer: Wrapping data and methods into class.
- What is Abstraction?Answer: Hiding implementation details.
- What is Inheritance?Answer: Acquiring properties of parent class.
- What is Polymorphism?Answer: Ability to perform multiple tasks with same method.
- What is Compile Time Polymorphism?Answer: Method overloading.
- What is Runtime Polymorphism?Answer: Method overriding.
- What is Dynamic Binding?Answer: Method call resolved at runtime.
- What is Static Binding?Answer: Method call resolved at compile time.
- What is Abstract Class?Answer: Class with abstract methods.
- What is Interface?Answer: Blueprint with abstract methods.
- What is Multiple Inheritance?Answer: Java supports via interfaces.
- What is Object Class?Answer: Root class of Java.
- What is toString() method?Answer: Returns string representation of object.
- What is equals() method?Answer: Compares object content.
- What is hashCode() method?Answer: Returns unique integer for object.
- What is finalize() method?Answer: Called before garbage collection.
- What is Garbage Collection?Answer: Automatic memory cleanup.
- What is Exception?Answer: Runtime error.
- What is Checked Exception?Answer: Checked at compile time.
- What is Unchecked Exception?Answer: Checked at runtime.
- What is try block?Answer: Contains risky code.
- What is catch block?Answer: Handles exception.
- What is finally block?Answer: Executes always.
- What is Thread?Answer: Lightweight process.
- What is Multithreading?Answer: Running multiple threads simultaneously.
- What is Runnable interface?Answer: Used to create thread.
- What is Thread class?Answer: Used to create thread.
- What is Synchronization?Answer: Controls thread access.
- What is Deadlock?Answer: Threads waiting for each other.
- What is Collection?Answer: Group of objects.
- What is List?Answer: Ordered collection.
- What is Set?Answer: Unique elements collection.
- What is Map?Answer: Key-value pair collection.
- What is ArrayList?Answer: Dynamic array.
- What is LinkedList?Answer: Doubly linked list.
- What is HashSet?Answer: Unique element set.
- What is TreeSet?Answer: Sorted set.
- What is HashMap?Answer: Key-value pair storage.
- What is TreeMap?Answer: Sorted key-value storage.
- What is Iterator?Answer: Used to traverse collection.
- What is Comparable?Answer: Used for sorting.
- What is Comparator?Answer: Custom sorting logic.
- What is Lambda?Answer: Anonymous function.
- What is Stream?Answer: Used to process collections.
- What is Optional?Answer: Avoid null pointer exception.
- What is Serialization?Answer: Convert object to byte stream.
- What is Deserialization?Answer: Convert byte stream to object.
- What is Enum?Answer: Fixed constants.
- What is Wrapper Class?Answer: Primitive to object conversion.
- What is Autoboxing?Answer: Primitive to wrapper conversion automatically.
- What is Unboxing?Answer: Wrapper to primitive conversion.
- What is Reflection?Answer: Inspect class at runtime.
- What is Singleton?Answer: Single instance class.
- What is Package?Answer: Group of classes.
- What is API?Answer: Predefined classes and methods.
- What is Java SE?Answer: Standard Edition.
- What is Java EE?Answer: Enterprise Edition.
- What is Java ME?Answer: Mobile Edition.
- What is JAR file?Answer: Java Archive file.
- What is WAR file?Answer: Web application archive.
- What is EAR file?Answer: Enterprise archive file.
- What is Classpath?Answer: Path of class files.
- What is JVM stack?Answer: Stores method calls.
- What is Heap area?Answer: Stores objects.
- What is Method overriding rule?Answer: Same signature and inheritance required.
- What is Method overloading rule?Answer: Different parameters required.
- What is Loose Coupling?Answer: Reduced dependency between classes.
- What is Tight Coupling?Answer: Strong dependency between classes.
- What is SOLID principle?Answer: OOP design principles.
- What is Dependency Injection?Answer: Providing dependency externally.
- What is MVC?Answer: Model View Controller architecture.
- Why Java is secure?Answer: JVM security, bytecode verifier, no pointers.
- Why Java is robust?Answer: Strong memory management and exception handling.
- Why Java is portable?Answer: Bytecode runs on any JVM.
- Why Java is object-oriented?Answer: Uses classes and objects.
📢 Join Our WhatsApp Channel
💼 Get Daily IT Job Updates, Interview Preparation Tips & Instant Alerts directly on WhatsApp.
👉 Join WhatsApp Now📢 Join Our Telegram Channel
💼 Get Daily IT Job Updates, Interview Tips & Exclusive Alerts directly on Telegram!
👉 Join Telegram