homework

package nice;

abstract class Abs {
 public abstract void f(int x);
 public abstract void g(int x,int y);
 public abstract void h(double x);
}
class F extends Abs {
 public void f(int x) {
  System.out.println("f: "+x);
 }
 public  void g(int x,int y){ 
 }
 public  void h(double x){ 
 }
}
class G extends Abs {
 public void f(int x) { 
 }
 public  void g(int x,int y){
  System.out.print("g: "+x+" , ");
  System.out.println(y);
 }
 public  void h(double x){ 
 }
}
class H extends Abs {
 public void f(int x) {  
 }
 public  void g(int x,int y){
 }
 public  void h(double x){
  System.out.println("h: "+x);
 }
}
public class Abstract {
 public static void main(String[]args) {
 Abs fAbs = new F();
 fAbs.f(10);
 Abs gAbs = new G();
 gAbs.g(12,13);
 Abs hAbs = new H();
 hAbs.h(20.0);
 }
}