Question

Java 编写一个矩形类实现shape接口。 编写一个圆类实现shape接口。 编写一个主类用来测

Java
编写一个矩形类实现shape接口。
编写一个圆类实现shape接口。
编写一个主类用来测试上述各接口。

Answer 1

/**
*
* @author Administrator
* 图形接口
*
*/
public interface shape {
// 得到面积
public double getArea (int radiusOrLength, int width);
// 得到周长
public double getPerimeter(int radiusOrLength, int width);
}
/**
*
* @author Administrator
* 圆形
*/
public class Circle implements shape{

// π定义
private final static double PI = 3.14;
@Override
public double getArea(int radius, int width) {
double area = Math.sqrt(radius)* PI;
return area;

}
@Override
public double getPerimeter(int radius, int width) {
double perimeter = 2*radius* PI;
return perimeter;
}

}
/**
* 长方形
* @author Administrator
*
*/
public class Rectangle implements shape{

@Override
public double getArea(int length, int width) {
double area = length*width;
return area;
}

@Override
public double getPerimeter(int length, int width) {
double perimeter = 2*(length + width);
return perimeter;
}
}
/**
* 正方形
* @author Administrator
*
*/
public class Square extends Rectangle {
public double getArea(int length, int width) {
return super.getArea(length, width);

}
}
import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;
public class Main {
private static int radius= 0;
private static int length = 0;
private static int width = 0;
private static int shape = 0;
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
InputStream in = System.in;
Scanner scan = new Scanner(in);
System.out.println("********************************************");
System.out.println("请输入图形及它们的半径或者长宽");
System.out.println("1表示圆");
System.out.println("2表示长方形");
System.out.println("3表示正方形");
System.out.println("********************************************");
System.out.print("请输入图形:");
shape = (int)scan.nextInt();
getShape(shape);
switch (shape) {
case 1 :
Circle circle = new Circle();
System.out.println("圆的面积："+ circle.getArea(radius, 0) );
System.out.println("圆的周长："+ circle.getPerimeter(radius, 0));
break;
case 2:
Rectangle rectangle = new Rectangle();
System.out.println("长方形的面积："+ rectangle.getArea(length, width));
System.out.println("长方形的周长：" + rectangle.getPerimeter(length, width));
break;
case 3:
Square square = new Square();
System.out.println("正方形的面积："+ square.getArea(length, length));
System.out.println("正方形的周长：" + square.getPerimeter(length, length) );
break;
default:
System.out.println("输入有误!" );
}
}
public static void getShape(int shape) {
InputStream in = System.in;
Scanner scan = new Scanner(in);
switch (shape) {
case 1 :
System.out.println("请输入的半径" );
radius = (int)scan.nextInt();
break;
case 2:
getLenWid();
break;
case 3:
System.out.println("请输入正方形的长" );
length = (int)scan.nextInt();
break;
default:
System.out.println("输入有误，请重新选择！" );
getShape(shape);
}
}

public static void getLenWid() {
InputStream in = System.in;
Scanner scan = new Scanner(in);
System.out.println("请输入长方形的长" );
length = (int)scan.nextInt();
System.out.println("请输入长方形的宽" );
width = (int)scan.nextInt();
if (length <= width) {
System.out.println("长方形的长度大于宽度！" );
getLenWid();
}
}
}

Answer 2

鄙人在这里提供一个不同的解法，接口里方法不传参数
1.接口定义如下：
public interface Shape {
 public double area();
 public double length();
}
2.圆定义如下：

public class Circle implements Shape{
 private final double  Pi=3.141596;
 public double r;
 
 @Override
 public double area() {
  // TODO Auto-generated method stub
  
  return r*r*Pi;
 }
 @Override
 public double length() {
  // TODO Auto-generated method stub
  return 2*r*Pi;
 }
}
3.矩形定义如下：

public class Juxing implements Shape{
 
 public int len1;
 public int len2;
 @Override
 public double area() {
  // TODO Auto-generated method stub
  return len1*len2;
 }
 @Override
 public double length() {
  // TODO Auto-generated method stub
  return 2*(len1+len2);
 }
}
4.测试类如下：

public class Test {
 
 public static void main(String[] args){
  
  Circle c= new Circle();
  c.r=3;
  System.out.println("\nThis is Circle(r=3) area="+c.area());
  System.out.println("This is Circle(r=3) length="+c.length());
  
  Juxing ju= new Juxing();
  ju.len1=4;
  ju.len2=5;
  System.out.println("\nThis is juxing's area= "+ju.area());
  System.out.println("This is Juxing's length= "+ju.length());
 }
}