public class Ex09 { public static void main(String[] args){ Data d = new Data(); d.x = 10; System.out.println("main():x="+d.x); Ex09 e = new Ex09(); e.change(d.x); System.out.println("main():x=" +d.x); } void change(int x){ x = 1000; System.out.println("challenge():x="+x); } } class Data{ int x; }