Object Class

title: Object Class in Java description: Java ka root class - Object class

java.lang.Object Java mein sabse parent class hai. Har class implicitly Object extend karti hai.

Important Methods

toString()

java exampleWoHoTech

class Student {
    String name;
    int age;

    @Override
    public String toString() {
        return "Student{name='" + name + "', age=" + age + "}";
    }
}
Student s = new Student();
s.name = "Ram"; s.age = 20;
System.out.println(s); // "Student{name='Ram', age=20}"

equals()

java exampleWoHoTech

class Point {
    int x, y;
    Point(int x, int y) { this.x = x; this.y = y; }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof Point)) return false;
        Point p = (Point) obj;
        return x == p.x && y == p.y;
    }
}

hashCode()

java exampleWoHoTech

@Override
public int hashCode() {
    return Objects.hash(x, y);
}

equals() override karo to hashCode() bhi override karo — contract hai.

getClass()

java exampleWoHoTech

Object obj = new String("Hello");
System.out.println(obj.getClass().getName()); // java.lang.String
System.out.println(obj.getClass().getSimpleName()); // String

clone() — Object copy

java exampleWoHoTech

class MyClass implements Cloneable {
    int data;
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

finalize() — Deprecated Java 9+

Object garbage collect hone se pehle call hota tha.

title: Object Class in Java description: Java ka root class - Object class

java.lang.Object Java mein sabse parent class hai. Har class implicitly Object extend karti hai.

Important Methods

toString()

java exampleWoHoTech

class Student {
    String name;
    int age;

    @Override
    public String toString() {
        return "Student{name='" + name + "', age=" + age + "}";
    }
}
Student s = new Student();
s.name = "Ram"; s.age = 20;
System.out.println(s); // "Student{name='Ram', age=20}"

equals()

java exampleWoHoTech

class Point {
    int x, y;
    Point(int x, int y) { this.x = x; this.y = y; }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof Point)) return false;
        Point p = (Point) obj;
        return x == p.x && y == p.y;
    }
}

hashCode()

java exampleWoHoTech

@Override
public int hashCode() {
    return Objects.hash(x, y);
}

equals() override karo to hashCode() bhi override karo — contract hai.

getClass()

java exampleWoHoTech

Object obj = new String("Hello");
System.out.println(obj.getClass().getName()); // java.lang.String
System.out.println(obj.getClass().getSimpleName()); // String

clone() — Object copy

java exampleWoHoTech

class MyClass implements Cloneable {
    int data;
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

finalize() — Deprecated Java 9+

Object garbage collect hone se pehle call hota tha.

Object Class

Important Methods

toString()

equals()

hashCode()

getClass()

clone() — Object copy

finalize() — Deprecated Java 9+

Continue learning this concept

Object Class

Important Methods

toString()

equals()

hashCode()

getClass()

clone() — Object copy

finalize() — Deprecated Java 9+

Continue learning this concept