Class Demo

import java.io.*;
class Student
{
    private int roll_no;
    private String name;
    void get_data(String name,int roll_no)
    {
        this.name=name;
        this.roll_no=roll_no;
    }

    void display()
    {
        System.out.print("\nStudent Details: ");
        System.out.print("\nName: "+name);
        System.out.print("\nRoll_no: "+roll_no);
    }
}

class ClassDemo
{
    public static void main(String s[]) throws Exception
    {
        Student s1=new Student();
        Student s2=new Student();

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        System.out.print("\nEnter Name: ");
        String name = br.readLine();

        System.out.print("\nEnter Roll no: ");
        int roll_no = Integer.parseInt(br.readLine());

        s1.get_data(name,roll_no);
        s1.display();

        System.out.println();
    }
}

Output