ICSE − Q & A

What's copy constructor ?

Plz point out my mistake in the prog.: 
import java.io.*;
class FruitJuice
    {
        int product_code,pack_size,product_price;
        String flavour,pac_type;
        FruitJuice()
        {
            product_code=0;
            pack_size=0;
            product_price=0;
            flavour="";
            pac_type="";
        }
        void input()throws IOException
        {
            BufferedReader inp=new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Enter pcode psize pprice flavour pactype");
            product_code=Integer.parseInt(inp.readLine());
            pack_size=Integer.parseInt(inp.readLine());
            product_price=Integer.parseInt(inp.readLine());
            flavour=inp.readLine();
            pac_type=inp.readLine();
        }
        void discount()
        {
            product_price=product_price-10;
        }
        void display()
        {
            System.out.println("P code="+product_code);
            System.out.println("P size="+pack_size);
            System.out.println("P price="+product_price);
            System.out.println("Flavour="+flavour);
            System.out.println("P type="+pac_type);
        }
        public static void main(String args[])
        {
            FruitJuice ob=new FruitJuice();
            ob.input();
            ob.discount();
            ob.display();
        }
    }

Dif between compiler and interpretor

diff between class n instance variable

To input strings through scanner do we write sc.next() or sc.nextLine() ??

ATB to all of you idiots XD
But the fact is the match was fixed