"use strict"; const {Fragment: _Fragment, jsx: _jsx, jsxs: _jsxs} = arguments[0]; const {useMDXComponents: _provideComponents} = arguments[0]; function _createMdxContent(props) { const _components = { code: "code", h3: "h3", li: "li", ol: "ol", p: "p", pre: "pre", strong: "strong", table: "table", tbody: "tbody", td: "td", th: "th", thead: "thead", tr: "tr", ul: "ul", ..._provideComponents(), ...props.components }, {Analogy, CodeBlock, ComparisonTable, DefinitionEntry, DefinitionGroup, English, Explanation, Hinglish, HowItWorks, ImportantQA, KeyPoints, MCQ, Remember, SubTopicHeader, TopicOverview} = _components; if (!Analogy) _missingMdxReference("Analogy", true); if (!CodeBlock) _missingMdxReference("CodeBlock", true); if (!ComparisonTable) _missingMdxReference("ComparisonTable", true); if (!DefinitionEntry) _missingMdxReference("DefinitionEntry", true); if (!DefinitionGroup) _missingMdxReference("DefinitionGroup", true); if (!English) _missingMdxReference("English", true); if (!Explanation) _missingMdxReference("Explanation", true); if (!Hinglish) _missingMdxReference("Hinglish", true); if (!HowItWorks) _missingMdxReference("HowItWorks", true); if (!ImportantQA) _missingMdxReference("ImportantQA", true); if (!KeyPoints) _missingMdxReference("KeyPoints", true); if (!MCQ) _missingMdxReference("MCQ", true); if (!Remember) _missingMdxReference("Remember", true); if (!SubTopicHeader) _missingMdxReference("SubTopicHeader", true); if (!TopicOverview) _missingMdxReference("TopicOverview", true); return _jsxs(_Fragment, { children: [_jsx(SubTopicHeader, { id: "1.2", title: "Defining a Class, Creating Object, Accessing Class Members" }), "\n", _jsxs(TopicOverview, { title: "Defining a Class, Creating Object, Accessing Class Members", topicId: "1.2", readingTime: "8 min read", difficulty: "Easy", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["Classes and objects are the heart of Java programming. Everything in Java revolves around classes — they are the blueprints from which objects are created. In this subtopic, we learn how to define a class with fields and methods, how to create objects from that class using the ", _jsx(_components.code, { children: "new" }), " keyword, and how to access an object's members using the dot operator. Mastering these basics is essential because every Java program you write will use classes and objects."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: ["Classes aur objects Java programming ka dil hain. Java mein sab kuch classes ke around ghumta hai — yeh woh blueprints hain jin se objects banaye jaate hain. Is subtopic mein hum seekhenge ki class kaise define karte hain fields aur methods ke saath, ", _jsx(_components.code, { children: "new" }), " keyword se us class se objects kaise create karte hain, aur dot operator se object ke members ko kaise access karte hain. In basics ko master karna zaroori hai kyunki tumhara har Java program classes aur objects use karega."] }) })] }), "\n", _jsxs(DefinitionGroup, { children: [_jsxs(DefinitionEntry, { term: "Class", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["A ", _jsx(_components.strong, { children: "class" }), " is a user-defined blueprint or template in Java that defines the structure (fields) and behavior (methods) of objects. It is like a cookie cutter — the cutter itself isn't a cookie, but it defines the shape of every cookie you make from it."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Class" }), " Java mein ek user-defined blueprint ya template hota hai jo objects ki structure (fields) aur behavior (methods) define karta hai. Yeh cookie cutter jaisa hai — cutter khud cookie nahi hai, lekin yeh har cookie ka shape define karta hai jo tum usse banaoge."] }) })] }), _jsxs(DefinitionEntry, { term: "Object", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["An ", _jsx(_components.strong, { children: "object" }), " is a runtime instance of a class. When you create an object, memory is allocated for it and it can hold its own data and perform actions defined in its class. If the class is the blueprint, the object is the actual house built from it."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Object" }), " class ka ek runtime instance hota hai. Jab tum object create karte ho, toh uske liye memory allocate hoti hai aur woh apna data store kar sakta hai aur apni class mein defined actions perform kar sakta hai. Agar class blueprint hai, toh object usse bana hua actual ghar hai."] }) })] }), _jsxs(DefinitionEntry, { term: "Instance Variable (Field)", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["An ", _jsx(_components.strong, { children: "instance variable" }), " (also called a field) is a variable declared inside a class but outside any method. Each object has its own copy of instance variables, which means different objects can hold different values for the same fields."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Instance variable" }), " (ise field bhi kehte hain) ek variable hota hai jo class ke andar declare kiya jaata hai lekin kisi method ke bahar. Har object ki instance variables ki apni alag copy hoti hai, iska matlab alag objects same fields ke liye alag values store kar sakte hain."] }) })] }), _jsxs(DefinitionEntry, { term: "Method", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["A ", _jsx(_components.strong, { children: "method" }), " is a block of code defined inside a class that performs a specific task. Methods describe the behavior of objects — what actions they can perform. For example, a ", _jsx(_components.code, { children: "display()" }), " method might print an object's data."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Method" }), " class ke andar defined ek code block hota hai jo ek specific task perform karta hai. Methods objects ki behavior describe karte hain — ki woh kya actions perform kar sakte hain. For example, ", _jsx(_components.code, { children: "display()" }), " method object ka data print kar sakta hai."] }) })] }), _jsxs(DefinitionEntry, { term: "Reference Variable", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["A ", _jsx(_components.strong, { children: "reference variable" }), " is a variable that holds the memory address (reference) of an object, not the object itself. When you write ", _jsx(_components.code, { children: "Student s1 = new Student();" }), ", ", _jsx(_components.code, { children: "s1" }), " is the reference variable that points to the actual object in memory."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Reference variable" }), " ek variable hota hai jo object ki memory address (reference) store karta hai, object khud nahi. Jab tum ", _jsx(_components.code, { children: "Student s1 = new Student();" }), " likhte ho, toh ", _jsx(_components.code, { children: "s1" }), " woh reference variable hai jo memory mein actual object ko point karta hai."] }) })] }), _jsxs(DefinitionEntry, { term: "new keyword", children: [_jsx(English, { children: _jsxs(_components.p, { children: ["The ", _jsxs(_components.strong, { children: [_jsx(_components.code, { children: "new" }), " keyword"] }), " in Java is used to create a new object. It allocates memory on the heap for the object and calls the constructor to initialize it. Without ", _jsx(_components.code, { children: "new" }), ", you only have a reference variable that does not point to any object."] }) }), _jsx(Hinglish, { children: _jsxs(_components.p, { children: ["Java mein ", _jsxs(_components.strong, { children: [_jsx(_components.code, { children: "new" }), " keyword"] }), " naya object create karne ke liye use hota hai. Yeh heap pe object ke liye memory allocate karta hai aur constructor call karke usse initialize karta hai. ", _jsx(_components.code, { children: "new" }), " ke bina tumhare paas sirf ek reference variable hota hai jo kisi object ko point nahi karta."] }) })] })] }), "\n", _jsxs(Explanation, { children: [_jsxs(English, { children: [_jsx(_components.h3, { children: "🏗️ Anatomy of a Class" }), _jsxs(_components.p, { children: ["Let us understand the structure of a Java class with a real example. Consider a ", _jsx(_components.code, { children: "Student" }), " class that models student data:"] })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "🏗️ Class ki Structure samajhte hain" }), _jsxs(_components.p, { children: ["Ek real example se Java class ki structure samajhte hain. Maan lo ek ", _jsx(_components.code, { children: "Student" }), " class hai jo student data ko model karta hai:"] })] }), _jsx(CodeBlock, { language: "java", children: `class Student { // Instance Variables (Fields) String name; int rollNo; // Method void display() { System.out.println("Name: " + name); System.out.println("Roll No: " + rollNo); } }` }), _jsxs(English, { children: [_jsx(_components.p, { children: "Here is what each part does:" }), _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: _jsx(_components.code, { children: "class Student" }) }), " — This declares a class named ", _jsx(_components.code, { children: "Student" }), ". The ", _jsx(_components.code, { children: "class" }), " keyword tells Java that you are defining a new class, and ", _jsx(_components.code, { children: "Student" }), " is the name you have given it."] }), "\n", _jsxs(_components.li, { children: [_jsxs(_components.strong, { children: [_jsx(_components.code, { children: "String name;" }), " and ", _jsx(_components.code, { children: "int rollNo;" })] }), " — These are instance variables (fields). Every ", _jsx(_components.code, { children: "Student" }), " object will have its own ", _jsx(_components.code, { children: "name" }), " and ", _jsx(_components.code, { children: "rollNo" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: _jsx(_components.code, { children: "void display()" }) }), " — This is a method. It does not return any value (", _jsx(_components.code, { children: "void" }), "), and it prints the student's details when called."] }), "\n"] }), _jsx(_components.p, { children: "Notice that the class itself does not print anything or do anything on its own — it is just a definition. The actual work happens when we create objects from it." })] }), _jsxs(Hinglish, { children: [_jsx(_components.p, { children: "Har part kya karta hai yeh samajhte hain:" }), _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: _jsx(_components.code, { children: "class Student" }) }), " — Yeh ek ", _jsx(_components.code, { children: "Student" }), " naam ki class declare karta hai. ", _jsx(_components.code, { children: "class" }), " keyword Java ko batata hai ki tum ek nayi class define kar rahe ho, aur ", _jsx(_components.code, { children: "Student" }), " uska naam hai."] }), "\n", _jsxs(_components.li, { children: [_jsxs(_components.strong, { children: [_jsx(_components.code, { children: "String name;" }), " aur ", _jsx(_components.code, { children: "int rollNo;" })] }), " — Yeh instance variables (fields) hain. Har ", _jsx(_components.code, { children: "Student" }), " object ka apna ", _jsx(_components.code, { children: "name" }), " aur ", _jsx(_components.code, { children: "rollNo" }), " hoga."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: _jsx(_components.code, { children: "void display()" }) }), " — Yeh ek method hai. Yeh koi value return nahi karta (", _jsx(_components.code, { children: "void" }), "), aur jab isse call kiya jaata hai toh student ka details print karta hai."] }), "\n"] }), _jsx(_components.p, { children: "Dekho, class khud kuch print nahi karti ya kuch karti nahi — yeh sirf ek definition hai. Actual work tab hota hai jab hum isse objects banate hain." })] }), _jsxs(Analogy, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "The Blueprint Analogy 🏠" }) }), _jsxs(_components.p, { children: ["Think of a class as an ", _jsx(_components.strong, { children: "architectural blueprint" }), " of a house. The blueprint describes where the rooms are, how big they are, and where the doors and windows go. But the blueprint itself is not a house — you cannot live in it!"] }), _jsxs(_components.p, { children: ["An ", _jsx(_components.strong, { children: "object" }), " is the actual house built from that blueprint. You can build multiple houses (objects) from the same blueprint (class), and each house can have different paint colors, furniture, and occupants — just like each object can have different values for its fields."] })] }), _jsxs(English, { children: [_jsx(_components.h3, { children: "⚖️ Class vs Object — What is the Difference?" }), _jsx(_components.p, { children: "It is easy to confuse classes and objects, especially when you are starting out. Here is a clear comparison:" })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "⚖️ Class aur Object — Kya farq hai?" }), _jsx(_components.p, { children: "Classes aur objects ko confuse karna aam baat hai, especially jab tum start kar rahe ho. Yeh raha ek clear comparison:" })] }), _jsx(ComparisonTable, { title: "Class vs Object", children: _jsxs(_components.table, { children: [_jsx(_components.thead, { children: _jsxs(_components.tr, { children: [_jsx(_components.th, { children: "Aspect" }), _jsx(_components.th, { children: "Class" }), _jsx(_components.th, { children: "Object" })] }) }), _jsxs(_components.tbody, { children: [_jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "What is it?" }) }), _jsx(_components.td, { children: "Blueprint / Template" }), _jsx(_components.td, { children: "Instance of a class" })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "Memory" }) }), _jsx(_components.td, { children: "No memory allocated" }), _jsx(_components.td, { children: "Memory allocated on heap" })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "Created using" }) }), _jsxs(_components.td, { children: [_jsx(_components.code, { children: "class" }), " keyword"] }), _jsxs(_components.td, { children: [_jsx(_components.code, { children: "new" }), " keyword"] })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "How many?" }) }), _jsx(_components.td, { children: "Defined once" }), _jsx(_components.td, { children: "Multiple objects from one class" })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "Contains" }) }), _jsx(_components.td, { children: "Field declarations and method definitions" }), _jsx(_components.td, { children: "Actual data values and method behavior" })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.strong, { children: "Example" }) }), _jsx(_components.td, { children: _jsx(_components.code, { children: "class Student { int rollNo; }" }) }), _jsx(_components.td, { children: _jsx(_components.code, { children: "Student s1 = new Student();" }) })] })] })] }) }), _jsxs(English, { children: [_jsx(_components.h3, { children: "🔨 Creating an Object — Step by Step" }), _jsx(_components.p, { children: "Creating an object in Java involves three steps that often get combined into a single line. Let us break it down:" })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "🔨 Object banana — Step by Step" }), _jsx(_components.p, { children: "Java mein object create karna teen steps involve karta hai jo aksar ek single line mein combine ho jaate hain. Isko break down karte hain:" })] }), _jsxs(HowItWorks, { title: "How Object Creation Works", children: [_jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Step 1: Declare a Reference Variable" }), "\nFirst, you declare a variable of the class type. At this point, no object exists — you just have a variable that can hold a reference to a Student object.\n", _jsx(_components.code, { children: "Student s1;" })] }), _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Step 2: Create the Object with new" }), "\nThe ", _jsx(_components.code, { children: "new" }), " keyword allocates memory on the heap for a new Student object and calls the default constructor to initialize it."] }), _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Step 3: Assign the Reference" }), "\nThe reference returned by ", _jsx(_components.code, { children: "new" }), " is stored in the variable ", _jsx(_components.code, { children: "s1" }), ". Now ", _jsx(_components.code, { children: "s1" }), " points to the actual object in memory.\n", _jsx(_components.code, { children: "s1 = new Student();" })] }), _jsxs(_components.p, { children: [_jsx(_components.strong, { children: "Combined (Most Common Way)" }), "\nIn practice, all three steps are written in one line:\n", _jsx(_components.code, { children: "Student s1 = new Student();" })] })] }), _jsxs(English, { children: [_jsx(_components.h3, { children: "🔗 Accessing Class Members — The Dot Operator" }), _jsxs(_components.p, { children: ["Once an object is created, you access its fields and methods using the ", _jsxs(_components.strong, { children: ["dot operator (", _jsx(_components.code, { children: "." }), ")"] }), ". The dot basically says: \"Hey object, give me this field\" or \"Hey object, run this method.\" Let us see this with a complete example:"] })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "🔗 Class Members access karna — Dot Operator" }), _jsxs(_components.p, { children: ["Jab object ban jaata hai, toh tum uske fields aur methods ko ", _jsxs(_components.strong, { children: ["dot operator (", _jsx(_components.code, { children: "." }), ")"] }), " se access karte ho. Dot basically yeh kehta hai: \"Hey object, mujhe yeh field do\" ya \"Hey object, yeh method run karo.\" Isko ek complete example se dekhte hain:"] })] }), _jsx(CodeBlock, { language: "java", children: `class Student { String name; int rollNo; void display() { System.out.println("Name: " + name); System.out.println("Roll No: " + rollNo); } public static void main(String[] args) { // Creating an object Student s1 = new Student(); // Accessing fields using dot operator s1.name = "Rahul"; s1.rollNo = 101; // Calling a method using dot operator s1.display(); } }` }), _jsxs(English, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\n" }) }), _jsx(_components.p, { children: "Here is what happened step by step:" }), _jsxs(_components.ol, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "Student s1 = new Student();" }), " — Created a new ", _jsx(_components.code, { children: "Student" }), " object and stored its reference in ", _jsx(_components.code, { children: "s1" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.name = \"Rahul\";" }), " — Accessed the ", _jsx(_components.code, { children: "name" }), " field of ", _jsx(_components.code, { children: "s1" }), " and assigned it the value ", _jsx(_components.code, { children: "\"Rahul\"" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.rollNo = 101;" }), " — Accessed the ", _jsx(_components.code, { children: "rollNo" }), " field of ", _jsx(_components.code, { children: "s1" }), " and assigned it the value ", _jsx(_components.code, { children: "101" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.display();" }), " — Called the ", _jsx(_components.code, { children: "display()" }), " method of ", _jsx(_components.code, { children: "s1" }), ", which printed the student's details."] }), "\n"] })] }), _jsxs(Hinglish, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\n" }) }), _jsx(_components.p, { children: "Yeh hua kya step by step:" }), _jsxs(_components.ol, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "Student s1 = new Student();" }), " — Naya ", _jsx(_components.code, { children: "Student" }), " object create kiya aur uska reference ", _jsx(_components.code, { children: "s1" }), " mein store kiya."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.name = \"Rahul\";" }), " — ", _jsx(_components.code, { children: "s1" }), " ka ", _jsx(_components.code, { children: "name" }), " field access kiya aur ", _jsx(_components.code, { children: "\"Rahul\"" }), " value assign ki."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.rollNo = 101;" }), " — ", _jsx(_components.code, { children: "s1" }), " ka ", _jsx(_components.code, { children: "rollNo" }), " field access kiya aur ", _jsx(_components.code, { children: "101" }), " value assign ki."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.code, { children: "s1.display();" }), " — ", _jsx(_components.code, { children: "s1" }), " ka ", _jsx(_components.code, { children: "display()" }), " method call kiya, jisne student ka details print kiya."] }), "\n"] })] }), _jsxs(Remember, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "⚠️ Common Mistakes to Avoid" }) }), _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Creating only a reference, not an object:" }), " Writing ", _jsx(_components.code, { children: "Student s1;" }), " only creates a reference variable. It does NOT create an object. If you try ", _jsx(_components.code, { children: "s1.display()" }), " without ", _jsx(_components.code, { children: "s1 = new Student();" }), ", you will get a ", _jsx(_components.strong, { children: "compilation error" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Confusing class name with object name:" }), " ", _jsx(_components.code, { children: "Student" }), " is the class name (the type). ", _jsx(_components.code, { children: "s1" }), " is the object name (the variable). You cannot call ", _jsx(_components.code, { children: "Student.display()" }), " directly — you need an object like ", _jsx(_components.code, { children: "s1.display()" }), "."] }), "\n", _jsxs(_components.li, { children: [_jsx(_components.strong, { children: "Accessing members of wrong object type:" }), " ", _jsx(_components.code, { children: "s1.name = 101;" }), " will cause a compilation error because ", _jsx(_components.code, { children: "name" }), " is a ", _jsx(_components.code, { children: "String" }), ", not an ", _jsx(_components.code, { children: "int" }), ". Always match the data type when assigning values."] }), "\n"] })] }), _jsxs(English, { children: [_jsx(_components.h3, { children: "📦 Multiple Objects from One Class" }), _jsx(_components.p, { children: "One of the most powerful aspects of classes is that you can create as many objects as you want from a single class, and each object maintains its own separate data. Changing one object's data does not affect another object at all." })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "📦 Ek class se Multiple Objects" }), _jsx(_components.p, { children: "Classes ka sabse powerful aspect yeh hai ki tum ek single class se jitne chahe utne objects create kar sakte ho, aur har object apna alag data maintain karta hai. Ek object ka data change karne se doosre object pe bilkul koi effect nahi padta." })] }), _jsx(CodeBlock, { language: "java", children: `public static void main(String[] args) { // Creating first object Student s1 = new Student(); s1.name = "Rahul"; s1.rollNo = 101; // Creating second object Student s2 = new Student(); s2.name = "Priya"; s2.rollNo = 102; // Each object has its own data s1.display(); // Prints Rahul's details s2.display(); // Prints Priya's details }` }), _jsxs(English, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\nName: Priya\nRoll No: 102\n" }) }), _jsxs(_components.p, { children: ["Even though both ", _jsx(_components.code, { children: "s1" }), " and ", _jsx(_components.code, { children: "s2" }), " are created from the same ", _jsx(_components.code, { children: "Student" }), " class, they hold completely different data. Changing ", _jsx(_components.code, { children: "s1.name" }), " does not affect ", _jsx(_components.code, { children: "s2.name" }), " — each object is independent."] })] }), _jsxs(Hinglish, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\nName: Priya\nRoll No: 102\n" }) }), _jsxs(_components.p, { children: ["Chahe ", _jsx(_components.code, { children: "s1" }), " aur ", _jsx(_components.code, { children: "s2" }), " dono same ", _jsx(_components.code, { children: "Student" }), " class se create hue hain, lekin woh completely alag data hold karte hain. ", _jsx(_components.code, { children: "s1.name" }), " change karne se ", _jsx(_components.code, { children: "s2.name" }), " pe koi effect nahi padta — har object independent hai."] })] }), _jsx(_components.pre, { children: _jsx(_components.code, { className: "language-mermaid", children: "flowchart LR\n A[\"class Student
────────
String name
int rollNo
────────
void display()\"]\n B[\"s1: Student
────────
name = Rahul
rollNo = 101\"]\n C[\"s2: Student
────────
name = Priya
rollNo = 102\"]\n A -->|\"new Student()\"| B\n A -->|\"new Student()\"| C\n" }) }), _jsxs(English, { children: [_jsx(_components.h3, { children: "📊 Default Values of Instance Variables" }), _jsxs(_components.p, { children: ["When you create an object but do not assign values to its fields, Java automatically assigns ", _jsx(_components.strong, { children: "default values" }), " based on the data type:"] })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "📊 Instance Variables ke Default Values" }), _jsxs(_components.p, { children: ["Jab tum object create karte ho lekin fields ko values assign nahi karte, toh Java data type ke basis pe automatically ", _jsx(_components.strong, { children: "default values" }), " assign karta hai:"] })] }), _jsx(ComparisonTable, { title: "Default Values of Data Types", children: _jsxs(_components.table, { children: [_jsx(_components.thead, { children: _jsxs(_components.tr, { children: [_jsx(_components.th, { children: "Data Type" }), _jsx(_components.th, { children: "Default Value" })] }) }), _jsxs(_components.tbody, { children: [_jsxs(_components.tr, { children: [_jsxs(_components.td, { children: [_jsx(_components.code, { children: "byte" }), ", ", _jsx(_components.code, { children: "short" }), ", ", _jsx(_components.code, { children: "int" }), ", ", _jsx(_components.code, { children: "long" })] }), _jsx(_components.td, { children: _jsx(_components.code, { children: "0" }) })] }), _jsxs(_components.tr, { children: [_jsxs(_components.td, { children: [_jsx(_components.code, { children: "float" }), ", ", _jsx(_components.code, { children: "double" })] }), _jsx(_components.td, { children: _jsx(_components.code, { children: "0.0" }) })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.code, { children: "boolean" }) }), _jsx(_components.td, { children: _jsx(_components.code, { children: "false" }) })] }), _jsxs(_components.tr, { children: [_jsx(_components.td, { children: _jsx(_components.code, { children: "char" }) }), _jsxs(_components.td, { children: [_jsx(_components.code, { children: "'\\u0000'" }), " (null character)"] })] }), _jsxs(_components.tr, { children: [_jsxs(_components.td, { children: ["Object references (", _jsx(_components.code, { children: "String" }), ", etc.)"] }), _jsx(_components.td, { children: _jsx(_components.code, { children: "null" }) })] })] })] }) }), _jsxs(English, { children: [_jsxs(_components.p, { children: ["So if you create ", _jsx(_components.code, { children: "Student s1 = new Student();" }), " without setting any values and call ", _jsx(_components.code, { children: "s1.display()" }), ", the output will be:"] }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: null\nRoll No: 0\n" }) }), _jsxs(_components.p, { children: ["This happens because ", _jsx(_components.code, { children: "name" }), " is a ", _jsx(_components.code, { children: "String" }), " (reference type, defaults to ", _jsx(_components.code, { children: "null" }), ") and ", _jsx(_components.code, { children: "rollNo" }), " is an ", _jsx(_components.code, { children: "int" }), " (defaults to ", _jsx(_components.code, { children: "0" }), "). This is why it is good practice to always initialize your object's fields after creation."] })] }), _jsxs(Hinglish, { children: [_jsxs(_components.p, { children: ["Toh agar tum ", _jsx(_components.code, { children: "Student s1 = new Student();" }), " bina koi values set kiye create karo aur ", _jsx(_components.code, { children: "s1.display()" }), " call karo, toh output yeh hoga:"] }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: null\nRoll No: 0\n" }) }), _jsxs(_components.p, { children: ["Yeh isliye kyunki ", _jsx(_components.code, { children: "name" }), " ek ", _jsx(_components.code, { children: "String" }), " hai (reference type, default ", _jsx(_components.code, { children: "null" }), " hota hai) aur ", _jsx(_components.code, { children: "rollNo" }), " ek ", _jsx(_components.code, { children: "int" }), " hai (default ", _jsx(_components.code, { children: "0" }), " hota hai). Isliye acchi practice yeh hai ki object create karne ke baad uske fields ko hamesha initialize karo."] })] }), _jsxs(English, { children: [_jsx(_components.h3, { children: "🧪 Complete Working Example" }), _jsx(_components.p, { children: "Let us put everything together in a complete, runnable Java program that demonstrates class definition, object creation, and member access:" })] }), _jsxs(Hinglish, { children: [_jsx(_components.h3, { children: "🧪 Complete Working Example" }), _jsx(_components.p, { children: "Sab kuch ek complete, runnable Java program mein dekhte hain jo class definition, object creation, aur member access sab demonstrate karta hai:" })] }), _jsx(CodeBlock, { language: "java", children: `class Student { // Instance Variables String name; int rollNo; double marks; // Method to display student details void display() { System.out.println("Name: " + name); System.out.println("Roll No: " + rollNo); System.out.println("Marks: " + marks); System.out.println("----------------"); } // Method to check if student has passed void checkResult() { if (marks >= 40) { System.out.println(name + " has PASSED"); } else { System.out.println(name + " has FAILED"); } } public static void main(String[] args) { // Creating first object Student s1 = new Student(); s1.name = "Rahul"; s1.rollNo = 101; s1.marks = 85.5; // Creating second object Student s2 = new Student(); s2.name = "Priya"; s2.rollNo = 102; s2.marks = 32.0; // Creating third object (using default values) Student s3 = new Student(); // Accessing members and calling methods s1.display(); s1.checkResult(); s2.display(); s2.checkResult(); s3.display(); // Will show default values } }` }), _jsxs(English, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\nMarks: 85.5\n----------------\nRahul has PASSED\nName: Priya\nRoll No: 102\nMarks: 32.0\n----------------\nPriya has FAILED\nName: null\nRoll No: 0\nMarks: 0.0\n----------------\n" }) }), _jsxs(_components.p, { children: ["Notice that ", _jsx(_components.code, { children: "s3" }), " was created without assigning any values, so Java used default values — ", _jsx(_components.code, { children: "null" }), " for ", _jsx(_components.code, { children: "name" }), ", ", _jsx(_components.code, { children: "0" }), " for ", _jsx(_components.code, { children: "rollNo" }), ", and ", _jsx(_components.code, { children: "0.0" }), " for ", _jsx(_components.code, { children: "marks" }), ". This example also shows how methods like ", _jsx(_components.code, { children: "checkResult()" }), " can use the object's fields to perform logic."] })] }), _jsxs(Hinglish, { children: [_jsx(_components.p, { children: _jsx(_components.strong, { children: "Output:" }) }), _jsx(_components.pre, { children: _jsx(_components.code, { children: "Name: Rahul\nRoll No: 101\nMarks: 85.5\n----------------\nRahul has PASSED\nName: Priya\nRoll No: 102\nMarks: 32.0\n----------------\nPriya has FAILED\nName: null\nRoll No: 0\nMarks: 0.0\n----------------\n" }) }), _jsxs(_components.p, { children: ["Dekho ", _jsx(_components.code, { children: "s3" }), " mein koi values assign nahi ki, toh Java ne default values use ki — ", _jsx(_components.code, { children: "name" }), " ke liye ", _jsx(_components.code, { children: "null" }), ", ", _jsx(_components.code, { children: "rollNo" }), " ke liye ", _jsx(_components.code, { children: "0" }), ", aur ", _jsx(_components.code, { children: "marks" }), " ke liye ", _jsx(_components.code, { children: "0.0" }), ". Yeh example yeh bhi dikhata hai ki methods jaise ", _jsx(_components.code, { children: "checkResult()" }), " object ke fields use karke logic perform kar sakte hain."] })] }), _jsx(KeyPoints, { children: _jsxs(_components.ul, { children: ["\n", _jsxs(_components.li, { children: ["A ", _jsx(_components.strong, { children: "class" }), " is a blueprint/template that defines fields (data) and methods (behavior). It does not use memory by itself."] }), "\n", _jsxs(_components.li, { children: ["An ", _jsx(_components.strong, { children: "object" }), " is a runtime instance of a class created using the ", _jsx(_components.code, { children: "new" }), " keyword. Memory is allocated on the heap."] }), "\n", _jsxs(_components.li, { children: ["The ", _jsx(_components.strong, { children: "syntax" }), " for creating an object: ", _jsx(_components.code, { children: "ClassName objectName = new ClassName();" })] }), "\n", _jsxs(_components.li, { children: ["Use the ", _jsxs(_components.strong, { children: ["dot operator (", _jsx(_components.code, { children: "." }), ")"] }), " to access fields (", _jsx(_components.code, { children: "obj.field" }), ") and call methods (", _jsx(_components.code, { children: "obj.method()" }), ")."] }), "\n", _jsxs(_components.li, { children: ["Each object has its ", _jsx(_components.strong, { children: "own copy" }), " of instance variables — changing one object's data does not affect another's."] }), "\n", _jsxs(_components.li, { children: ["Instance variables get ", _jsx(_components.strong, { children: "default values" }), " if not initialized: ", _jsx(_components.code, { children: "0" }), " for numbers, ", _jsx(_components.code, { children: "false" }), " for boolean, ", _jsx(_components.code, { children: "null" }), " for references."] }), "\n", _jsxs(_components.li, { children: ["A ", _jsx(_components.strong, { children: "reference variable" }), " stores the address of the object, not the object itself."] }), "\n"] }) })] }), "\n", _jsx(ImportantQA, { questions: [{ "q": "Java mein class kya hoti hai aur iska main purpose kya hai?", "marks": 2, "a": { "components": [{ "type": "Explanation", "content": "**Class** ek blueprint ya template hota hai jo kisi specific type ke objects banane ke liye data (fields) aur behavior (methods) ko define karti hai. Ye ek user-defined data type hai jo encapsulation provide karti hai. **Main Purpose:** - **Code Reusability:** Ek baar class define karo, uske multiple objects bana sakte ho. - **Encapsulation:** Data aur methods ko ek unit mein bundle karke security badhata hai. - **Object Creation:** Class se hi real-world entities ke objects create hote hain. Class mein data members (variables) aur member functions (methods) hote hain. Object bina class ke nahi ban sakta!" }] } }, { "q": "Class se object create karne ke steps explain karo aur class members ko access karne ke tarike batao.", "marks": 4, "a": { "components": [{ "type": "Explanation", "content": "**Object Creation Steps:** 1. **Class Define Karo:** Pehle class ka code likho with fields aur methods. 2. **`new` keyword use karo:** `new` operator memory allocate karta hai aur object banata hai. 3. **Reference Variable banao:** Object ko store karne ke liye ek variable declare karo. ```java ClassName objectName = new ClassName(); ``` - `ClassName objectName`: Reference variable declare karta hai. - `new ClassName()`: Constructor call karke object create karta hai. **Class Members Access Karne ke Tarike:** - **Dot (.) operator use karo:** `objectName.memberName` - **Static Members:** Class ke through directly access hote hain: `ClassName.staticMember` - **Non-static Members:** Object ke through access karte hain. **Example:** ```java class Student { String name; // Data member void display() { // Member method System.out.println("Name: " + name); } } // Object creation and access Student s1 = new Student(); s1.name = "Rahul"; // Member access s1.display(); // Method call ```" }] } }, { "q": "Ek Java program likho jo class 'Car' define kare with brand, model, aur speed fields, ek method displayDetails(), aur dikhao object create karke uske members ko access kaise karte hain.", "marks": 6, "a": { "components": [{ "type": "Explanation", "content": "Here is a complete Java program demonstrating class definition, object creation, and member access: {`class Car { // Data members (fields) String brand; String model; int speed; // Member method void displayDetails() { System.out.println("Car Brand: " + brand); System.out.println("Model: " + model); System.out.println("Current Speed: " + speed + " km/h"); } void accelerate(int increment) { speed = speed + increment; System.out.println("Speed increased to: " + speed + " km/h"); } } public class CarDemo { public static void main(String[] args) { // Object creation Car myCar = new Car(); // Accessing and setting data members myCar.brand = "Toyota"; myCar.model = "Innova"; myCar.speed = 80; // Calling member methods myCar.displayDetails(); System.out.println("\\\\nAccelerating..."); myCar.accelerate(20); // Passing parameter to method myCar.displayDetails(); // Show updated speed } }`} **Output:** ``` Car Brand: Toyota Model: Innova Current Speed: 80 km/h Accelerating... Speed increased to: 100 km/h Car Brand: Toyota Model: Innova Current Speed: 100 km/h ``` Is program mein: - `Car` class ek blueprint hai jo car ke properties aur behavior define karti hai. - `myCar` object `Car` class ka instance hai. - Data members ko direct dot (.) operator se access aur assign kiya gaya hai. - Methods ko object ke through call kiya gaya hai." }] } }] }), "\n", _jsx(MCQ, { questions: [{ "id": "9800825f-50a6-4b4d-8cb2-432b769418ac", "q": "Which keyword is used to create a new object of a class in Java?", "options": ["this", "new", "create", "class"], "answer": 1, "hint": "The keyword to create a new object in Java.", "explanation": "The 'new' keyword allocates memory for a new object and calls the constructor to initialize it." }, { "id": "35a4468a-6d7b-462a-b005-7d86417971dc", "q": "What is the special method called that is invoked when an object is created, used to initialize the object?", "options": ["Initializer", "main", "factory", "Constructor"], "answer": 3, "hint": "A method with the same name as the class, used for initialization.", "explanation": "A constructor is a special method that has the same name as the class and is called automatically when an object is created." }, { "id": "2ba1cc04-66b6-4da7-adbb-7428f3ee21b9", "q": "What does a variable of a class type hold after an object is assigned to it?", "options": ["A reference to the object in memory", "The object itself directly in the variable", "A copy of the class definition", "The memory address of the class"], "answer": 0, "hint": "Consider the syntax: ClassName objectName = new ClassName();", "explanation": "In Java, an object variable is a reference to an object, not the object itself. The reference points to the object in memory." }, { "id": "7cd2b4c0-5167-4cbc-8678-8fc1c825bcd6", "q": "Which operator is used to access members (fields or methods) of an object?", "options": ["-> (arrow)", ":: (scope resolution)", ". (dot)", "::: (triple colon)"], "answer": 2, "hint": "Think about how you access a method or field of an object.", "explanation": "The dot (.) operator is used to access instance members (fields or methods) of an object through its reference." }, { "id": "6609ec30-6fa1-47df-92de-e273e7afc3e5", "q": "How do you access a static method of a class named 'MathUtils'?", "options": ["MathUtils obj = new MathUtils(); obj.staticMethod();", "MathUtils.staticMethod();", "static MathUtils.staticMethod();", "MathUtils::staticMethod();"], "answer": 1, "hint": "A member declared with the 'static' keyword belongs to the class, not to any specific object.", "explanation": "Static members belong to the class itself and can be accessed using the class name, without creating an object." }, { "id": "7fc44a6c-49a5-4238-859d-44c2e9b48fed", "q": "What happens if you define a parameterized constructor in a class and do not define a no-arg constructor?", "options": ["Java still provides a no-arg constructor automatically.", "The class becomes abstract.", "You cannot create objects of the class.", "You cannot create objects using a no-argument constructor call."], "answer": 3, "hint": "When you do not define any constructor, Java provides one automatically.", "explanation": "If no constructor is defined, Java automatically provides a no-argument default constructor. If you define any constructor, the default one is not provided." }, { "id": "fe4d8ff8-f711-444c-bbba-3d607674b81f", "q": "What is the scope of a variable declared inside a method?", "options": ["From its declaration to the end of the method block.", "Throughout the entire class.", "Throughout the entire program.", "Only on the line where it is declared."], "answer": 0, "hint": "A variable declared inside a method or a block has limited scope.", "explanation": "A local variable declared inside a method is only accessible within that method's block, from its declaration until the end of the block." }, { "id": "25b2a167-cf94-4d75-9003-edc017a08ca3", "q": "How can you access a private field of an object from outside its class?", "options": ["Directly using the field name.", "Using the 'friend' keyword.", "By calling public getter and setter methods.", "You cannot access it at all."], "answer": 2, "hint": "A field declared as 'private' is not accessible directly from outside the class.", "explanation": "Private members are only accessible within the same class. To access them from outside, you must use public getter and setter methods." }, { "id": "806487ab-9051-458f-b186-ecc47bc0f714", "q": "What is the purpose of the 'this' keyword inside a class method?", "options": ["To refer to the parent class.", "To refer to the current object instance.", "To call a static method.", "To inherit from another class."], "answer": 1, "hint": "The 'this' keyword is a reference to the current object.", "explanation": "Inside an instance method or constructor, 'this' refers to the current object, the one for which the method was called. It can be used to disambiguate between instance variables and parameters with the same name." }, { "id": "8c7cb902-208f-4245-b9b9-bc8e97fde5fe", "q": "In object-oriented programming, a class is best described as a:", "options": ["Physical object in memory.", "Data structure for primitive types only.", "Collection of static methods.", "Blueprint for creating objects."], "answer": 3, "hint": "A class is a blueprint or template for objects.", "explanation": "A class defines the structure (fields) and behavior (methods) that its objects will have. It serves as a blueprint from which objects are created." }], topicId: "1.2" })] }); } function MDXContent(props = {}) { const {wrapper: MDXLayout} = { ..._provideComponents(), ...props.components }; return MDXLayout ? _jsx(MDXLayout, { ...props, children: _jsx(_createMdxContent, { ...props }) }) : _createMdxContent(props); } return { default: MDXContent }; function _missingMdxReference(id, component) { throw new Error("Expected " + (component ? "component" : "object") + " `" + id + "` to be defined: you likely forgot to import, pass, or provide it."); }