Class and Object

title: Class and Object in Java description: Java mein class aur object ka concept aur use

Class kya hai?

Class ek blueprint/template hai jisse objects banate hain. Isme data (variables) aur behavior (methods) define hote hain.

java exampleWoHoTech

class Student {
    // Fields (Data / Attributes)
    String name;
    int age;
    double marks;

    // Methods (Behavior)
    void study() {
        System.out.println(name + " padh raha hai");
    }

    void showDetails() {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Marks: " + marks);
    }
}

Object kya hai?

Class ka ek real instance. new keyword se object banta hai. Har object ki apni memory hoti hai.

java exampleWoHoTech

public class Main {
    public static void main(String[] args) {

        // Object create karna
        Student s1 = new Student();

        // Fields assign karna
        s1.name = "Ram";
        s1.age = 20;
        s1.marks = 85.5;

        // Methods call karna
        s1.study();
        s1.showDetails();

        // Doosra object — alag memory
        Student s2 = new Student();
        s2.name = "Shyam";
        s2.age = 22;
        s2.marks = 92.0;

        s2.showDetails();
    }
}

Output

Name	Ram
Age	20
Marks	85.5
Name	Shyam
Age	22
Marks	92.0

Memory mein kya hota hai?

Class definition → Method Area mein store hoti hai
Objects → Heap mein store hote hain
References (s1, s2) → Stack mein store hote hain

Stack Heap ------ -------- s1 --------→ [name="Ram", age=20, marks=85.5] s2 --------→ [name="Shyam", age=22, marks=92.0]

Null Reference

java exampleWoHoTech

Student s = null;       // koi object point nahi kar raha
s.showDetails();        // NullPointerException!

Anonymous Object

java exampleWoHoTech

// Bina variable assign kiye directly use karo
new Student().study();  // Ek baar use, phir garbage collect

Class ke Components

Component	Description	Example
Fields	Data store karte hain	`String name;`
Methods	Behavior define karte hain	`void study()`
Constructor	Object initialize karta hai	`Student() {}`
Block	Initialization block	`{ }`
Nested Class	Class ke andar class	`class Inner {}`

title: Class and Object in Java description: Java mein class aur object ka concept aur use

Class kya hai?

Class ek blueprint/template hai jisse objects banate hain. Isme data (variables) aur behavior (methods) define hote hain.

java exampleWoHoTech

class Student {
    // Fields (Data / Attributes)
    String name;
    int age;
    double marks;

    // Methods (Behavior)
    void study() {
        System.out.println(name + " padh raha hai");
    }

    void showDetails() {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Marks: " + marks);
    }
}

Object kya hai?

Class ka ek real instance. new keyword se object banta hai. Har object ki apni memory hoti hai.

java exampleWoHoTech

public class Main {
    public static void main(String[] args) {

        // Object create karna
        Student s1 = new Student();

        // Fields assign karna
        s1.name = "Ram";
        s1.age = 20;
        s1.marks = 85.5;

        // Methods call karna
        s1.study();
        s1.showDetails();

        // Doosra object — alag memory
        Student s2 = new Student();
        s2.name = "Shyam";
        s2.age = 22;
        s2.marks = 92.0;

        s2.showDetails();
    }
}

Output

Name	Ram
Age	20
Marks	85.5
Name	Shyam
Age	22
Marks	92.0

Memory mein kya hota hai?

Class definition → Method Area mein store hoti hai
Objects → Heap mein store hote hain
References (s1, s2) → Stack mein store hote hain

Stack Heap ------ -------- s1 --------→ [name="Ram", age=20, marks=85.5] s2 --------→ [name="Shyam", age=22, marks=92.0]

Null Reference

java exampleWoHoTech

Student s = null;       // koi object point nahi kar raha
s.showDetails();        // NullPointerException!

Anonymous Object

java exampleWoHoTech

// Bina variable assign kiye directly use karo
new Student().study();  // Ek baar use, phir garbage collect

Class ke Components

Component	Description	Example
Fields	Data store karte hain	`String name;`
Methods	Behavior define karte hain	`void study()`
Constructor	Object initialize karta hai	`Student() {}`
Block	Initialization block	`{ }`
Nested Class	Class ke andar class	`class Inner {}`

Class and Object

Class kya hai?

Object kya hai?

Output

Memory mein kya hota hai?

Null Reference

Anonymous Object

Class ke Components

Continue learning this concept

Class and Object

Class kya hai?

Object kya hai?

Output

Memory mein kya hota hai?

Null Reference

Anonymous Object

Class ke Components

Continue learning this concept