Student.java

package Oops;

import java.util.Scanner;

class StudentInfo {
    String Name;
    int rollnum;
    String Address;
    String mob;

    // StudentInfo(){ // defualt constructor which will be executed when the object
    // is created...
    // // this keyword will assign all these values once the object is created
    // // so basically "this" keyword will replace thing written below...
    // // S1.Name = "kunal";
    // // S1.rollnum =12;
    // // scan.nextLine(); // consume leftover newline
    // // S1.Address = "kanput"; // full address
    // // S1.mob =9912124;

    // this.Name="Naman";
    // this.rollnum=1;
    // this.Address="Kanpur";
    // this.mob="xxxxxxxxxxx";
    // }

    StudentInfo(StudentInfo other) {
        this.Name = other.Name;
        this.rollnum = other.rollnum;
        this.Address = other.Address;
        this.mob = other.mob;
    }

    StudentInfo(int roll, String Name, String add, String Mobile) {

        this.Name = Name;
        this.rollnum = roll;
        this.Address = add;
        this.mob = Mobile;
    }
}

public class Student {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        StudentInfo S1 = new StudentInfo(58, "naman", "V21 yashoda nagar", "9912124411"); // here the constructor with
                                                                                          // three formal parameter will
                                                                                          // be called
        // and if we write StudentInfo() without passing any values then the one with
        // zero formal parameters will be called...
        // System.out.println("Enter the info of 1st student::");
        // StudentInfo S2 = new StudentInfo();

        // S1.Name = "kunal";
        // S1.rollnum =12;
        // scan.nextLine(); // consume leftover newline
        // S1.Address = "kanput"; // full address
        // S1.mob =9912124;

        System.out.println("The details of the first student is :: " +
                S1.Name + " " + S1.rollnum + " " +
                S1.Address + " " + S1.mob);
        // System.out.println("The details of the second student is :: " +
        // random.Name + " " + random.rollnum + " " +
        // random.Address + " " + random.mob);

        StudentInfo random = new StudentInfo(S1); // this will automatically call default one but if the default one is
                                                  // not there then
        System.out.println("The details of the second student is :: " +
                random.Name + " " + random.rollnum + " " +
                random.Address + " " + random.mob);

        scan.close();
    }
}