class SuperClass{
int a=5,b=8,c=85;
void show(){
	  System.out.println("a*b="+(a*b));
}
}
class SubClass extends SuperClass{
int b=26,d=32;
void show()	{
	  System.out.println("b+d="+(b+d));
}
}
public class ClassExchangeDemo{
public static void main(String args[]){
SuperClass super1,super2;                             //聲明基類對象
SubClass sub1,sub2;                                      //聲明子類對象
super1=new SuperClass();
sub1=new SubClass();
System.out.println("super1.a="+super1.a+"\tsuper1.b="+super1.b+"\tsuper1.c="+super1.c); 
super1.show();
System.out.println("sub1.b="+sub1.b+"\tsub1.c="+sub1.c+"\tsub1.d="+sub1.d);	 
sub1.show();
super2=(SuperClass)sub1;                               //子類對象轉換為基類對象
System.out.println("super2.a="+super2.a+"\tsuper2.b="+super2.b+"\tsuper2.c="+super2.c);
System.out.println("super2.show():\t");	
super2.show();
sub2=(SubClass)super2; 	                    //基類對象轉換為子類對象
System.out.println("sub2.a="+sub2.a+"\tsub2.b="+sub2.b+"\tsub2.d="+sub2.d);
System.out.println("sub2.show():\t");	
sub2.show();
}
}