What is the Constructor in Java and What Are Its Types?

A constructor is a special method that is automatically called when an object is created. It has the same name as the class and no return type.

1. Default Constructor

class Student {
    String name;
    int age;
    
    Student() {
        name = "Unknown";
        age = 0;
    }
    
    void display() {
        System.out.println("Name: " + name + ", Age: " + age);
    }
}

2. Parameterized Constructor

class Employee {
    int empId;
    String empName;
    
    Employee(int id, String name) {
        empId = id;
        empName = name;
    }
    
    void show() {
        System.out.println("ID: " + empId + ", Name: " + empName);
    }
}

3. Constructor Overloading

class Rectangle {
    double length, width;
    
    Rectangle() {
        length = 1;
        width = 1;
    }
    
    Rectangle(double side) {
        length = width = side;
    }
    
    Rectangle(double l, double w) {
        length = l;
        width = w;
    }
    
    double area() {
        return length * width;
    }
}

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