父类：

package Duotai;

public abstract class Shape {
 public abstract void perimeter(double x,double y);
 public abstract void perimeter(double r);
 public abstract void area(double x,double y);
 public abstract void area(double r);
}

矩形：

package Duotai;

public class Rectangle extends Shape {

 
 @Override
 public void perimeter(double x, double y) {
  // TODO Auto-generated method stub
  double peri=2*x*y;
  System.out.println("矩形的周长为："+peri);
 }

 @Override
 public void perimeter(double r) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void area(double x, double y) {
  // TODO Auto-generated method stub
  double area=x*y;
  System.out.println("矩形的面积为："+area);
 }

 @Override
 public void area(double r) {
  // TODO Auto-generated method stub
  
 }

}

圆形：

package Duotai;

public class Circle extends Shape {

 @Override
 public void perimeter(double x, double y) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void perimeter(double r) {
  // TODO Auto-generated method stub
  double pi=3.14;
  double peri=2*pi*r;
  System.out.println("圆形的周长为："+peri);
 }

 @Override
 public void area(double x, double y) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void area(double r) {
  // TODO Auto-generated method stub
  double pi=3.14;
  double area=pi*r*r;
  System.out.println("圆形的面积为："+area);
 }

}

测试类：

package Duotai;
import java.util.Scanner;
public class Initail03 {

 public static void main(String[] args) {
  // TODO Auto-generated method stub
  calculate();
 }
  public static void calculate(){
  Shape Rec1=new Rectangle();
  Shape Cir1=new Circle();
  Scanner input=new Scanner(System.in);//创建Scanner对象
  System.out.println("请输入图形：");
  String shape=input.next();
 
 
  switch(shape){
   case "rectangle":
   System.out.println("请输入矩形的长：");
   double length=input.nextDouble();
   System.out.println("请输入矩形的宽：");
   double width=input.nextDouble();
   Rec1.perimeter(length,width);
   Rec1.area(length,width);
     
   break;
   
   case "circle":
   System.out.println("请输入圆形的半径：");
   double radius=input.nextDouble();
   Cir1.perimeter(radius);
   Cir1.area(radius);
   
   break;
   
   default:
    System.out.println("输入有误，请输入正确图形");
    calculate();
    
  }
 } 
 

}