In Java, abstraction is the process of hiding the implementation details of a class or method and exposing only the essential features to the outside world.It lets you focus on what an object does rather than how it does it. Why Abstraction? Reduces complexity by hiding unnecessary details. Increases flexibility — implementation can change…
1. What is Inheritance? Inheritance is a mechanism in Java by which one class (child/subclass) can acquire the properties (fields) and behaviors (methods) of another class (parent/superclass). It promotes code reusability and method overriding. 2. Types of Inheritance in Java Java supports several types of inheritance: Single Inheritance A class inherits from one parent…
1. What is Encapsulation? Encapsulation is a mechanism of wrapping data (variables) and methods (functions) together into a single unit, typically a class, and restricting direct access to some of the object's components. This is done to protect the internal state of the object and ensure controlled access. Think of it as a capsule:…
1. static Purpose: Makes a member (variable or method) belong to the class rather than an instance. Usage: Static variable: shared across all instances of the class. Static method: can be called without creating an object. Example: class Example { static int count = 0; // shared by all objects static void showCount() {…
In Java, operators are special symbols that perform operations on variables and values.They can be grouped into several categories: 1. Arithmetic Operators Used for basic mathematical operations. OperatorDescriptionExample (a=10, b=3)Result+Additiona + b13-Subtractiona - b7*Multiplicationa * b30/Divisiona / b3%Modulus (remainder)a % b1++Increment (by 1)a++11--Decrement (by 1)a--9 2. Relational Operators Used to compare two values (result…
In Java, enums (short for enumerations) are a special type of class used to define a fixed set of constants. They’re type-safe, more powerful than just using final static constants, and can even have methods, fields, and constructors. 1. Basic Syntax enum Day { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY } enum Day…
In Java, the Arrays class is a utility class from the java.util package that provides a collection of static methods for working with arrays. It helps you perform common tasks like sorting, searching, comparing, filling, and converting arrays to strings without writing all the low-level loops yourself. Importing import java.util.Arrays; import java.util.Arrays; Common Methods…
1. Object Class Package: java.lang Role: The root class of all classes in Java. Every class inherits from Object. Key Methods: toString() Returns a string representation of the object. equals(Object obj) Checks if two objects are equal. hashCode() Returns a hash code for the object. getClass() Returns the runtime Class object of the object.…
Common Interfaces in java.lang InterfacePurposeKey MethodsAppendableAllows an object to receive appended character sequences. Implemented by classes like StringBuilder, StringBuffer, Writer.append(CharSequence csq), append(char c)CharSequenceRepresents a readable sequence of char values. Implemented by String, StringBuilder, StringBuffer, CharBuffer.length(), charAt(int index), subSequence(int start, int end)CloneableMarks classes whose objects can be cloned using Object.clone(). (Marker interface — no methods).(No…
StringBuffer and StringBuilder are both Java classes for creating and manipulating mutable sequences of characters, but they differ in thread safety and performance. Here’s a breakdown: FeatureStringBufferStringBuilderMutabilityMutable (like StringBuilder)Mutable (like StringBuffer)Thread SafetyYes — methods are synchronized, so multiple threads can use the same object without corrupting dataNo — methods are not synchronized, so unsafe…