Question

编写一个完整的Java Application 程序。包含接口ShapeArea，类Circle、Rectangle、Test。 ⑴接口ShapeArea

Answer 1

public class Test {

public static void main(String[] args) {
ShapeArea rectangle = new Rectangle(3, 4);
ShapeArea circle = new Circle(2);

System.out.println(rectangle.toString());
System.out.println(circle.toString());
}

}

interface ShapeArea{
public double getArea();
public double getPerimeter();
}

class Rectangle implements ShapeArea{
private double height;
private double width;

public Rectangle(double w, double h){
this.width = w;
this.height = h;
}

public double getArea() {
return height * width;
}

public double getPerimeter() {
return 2 * (height + width);
}

public String toString(){
return "width=" + width + ",height=" + height + ",perimeter=" + getPerimeter() + ",area" + getArea();
}

}

class Circle implements ShapeArea{

private double r;

public Circle(double r){
this.r = r;
}

public double getArea() {
return Math.PI * r * r;
}

public double getPerimeter() {
return 2 * Math.PI * r;
}

public String toString(){
return "r =" + r + ", area = " + getArea() + ", perimeter = " + getPerimeter();
}

}

-----------------
width=3.0,height=4.0,perimeter=14.0,area12.0
r =2.0, area = 12.566370614359172, perimeter = 12.566370614359172