Question

java设计图形（Shape）类及其子类（Circle、Rectangle）

1）. Shape提供计算面积方法area，子类覆盖

Answer 1

你好，刚好闲着帮你写一个：
Shape类：
public class Shape {

protected Point location;
public Shape(){

}
public double area(){
return 0.0;
}

}
Circle类：
public class Circle extends Shape{
private int r;
public Circle() {

}
public Circle(Point center,int r) {
super.location=center;
this.r = r;
}
public double area() {

return Math.PI*r*r ;
}
}
Rectangle类：
public class Rectangle extends Shape{
private int width;
private int height;
public Rectangle() {

}
public Rectangle(Point o,int width, int height) {
location=o;

this.width = width;
this.height = height;
}
public double area() {

return width*height;
}

}
我这里图方便，在创建圆的时候直接用圆心和半径创建，还有矩形也是用一个点位置和长宽创建，所以还要加一个点类：
public class Point {

public int x;
public int y;

public Point() {
}

public Point(int x, int y) {
this.x = x;
this.y = y;
}
}