<java>objet question

Bonjour,
j'ai un doute sur ce prg;le prg est le suivant

package Bookx;
public class Book 
{
	 String bookname;
	 String authorname;
	 String publisher;
	 int price;

 public void store(String tbookname,String tauthorname,String tpublisher,int tprice)
 {
	 bookname=tbookname;
	 authorname=tauthorname;
	 publisher=tpublisher;
	 price=tprice;
 }
 public void display()
 {
	 System.out.println("Book Name"+bookname);
	 System.out.println("Author Name"+authorname);
	 System.out.println("Publisher Name"+publisher);
	 System.out.println("Price"+price);
	 
 }
}

package Bookx;
public class Book1 
{
	public static void main(String[]args)
	{
		Book java=new Book();
		Book oracle=new Book();
		
		java.store("java Language","Packianathan","Anuragam",250);
		oracle.store("Orancledatabase","Packianathan","Anuragam",125);
		java.display();
		oracle.display();
		
	}
}

mon question est là
dans le public void store,on ecrit
bookname=tbookname;
authorname=tauthorname;
publisher=tpublisher;
price=tprice;

après on utilise plus ces tbookname,tauthorname,tpublisher,tprice
à quoi sert ces tbookname,tauthorname,tpublisher,tprice

aidez moi s'il vous plaît