编写一个抽象类，要求有三个抽象方法

abstract class A{
    public abstract void f(int x);
    public abstract void g(int x,int y);
    public abstract double h(double x);
}
class jia1 extends A{
    public void f(int x){
        System.out.println(x);
    }
    public void g(int x,int y){
        int z=x+y;
        System.out.println(z);
    }
    public double h(double x){
        return x;
    }
}
class jia2 extends A{
    public void f(int x){
        System.out.println(x+1);
    }
    public void g(int x,int y){
        int z=x+y+1;
        System.out.println(z);
    }
    public double h(double x){
        return x+1;
    }
}
class jia3 extends A{
    public void f(int x){
        System.out.println(x+2);
    }
    public void g(int x,int y){
        double z=x+y+2;
        System.out.println(z);
    }
    public double h(double x){
        return x+2;
    }
}
public class exercise5_2{
    public static void main(String args[ ]){
        A a=new jia1();
        a.f(8);
        a.g(3,5);
        System.out.println(a.h(6));
        a=new jia2();
        a.f(7);
        a.g(3,6);
        System.out.println(a.h(9));
        a=new jia3();
        a.f(5);
        a.g(23,12);
        System.out.println(a.h(34));
    }
}