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public class Main {
public static void main(String[] args) {
Shape s = null;
s = new Circle(3);
System.out.println("åçé¢ç§¯ï¼" + s.area());
System.out.println("åçå¨é¿ï¼" + s.perimeter());
}
}
/**
* å½¢ç¶ç±»ï¼æ½è±¡ç±»
* @author developer
* @version 2017.05.23
*/
abstract class Shape {
/**
* 计ç®å½¢ç¶çé¢ç§¯
* @return å½¢ç¶çé¢ç§¯
*/
abstract double area();
/**
* 计ç®å½¢ç¶çå¨é¿
* @return å½¢ç¶çå¨é¿
*/
abstract double perimeter();
}
/**
* åç±»
* @author developer
* @version 2017.05.23
*/
class Circle extends Shape {
/**
* åå¾
*/
protected double radius;
/**
* æé æ¹æ³
* @param radius åå¾
*/
public Circle(double radius) {
this.radius = radius;
}
@Override
double area() {
return Math.PI * radius * radius;
}
@Override
double perimeter() {
return 2 * Math.PI * radius;
}
}
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åçé¢ç§¯ï¼28.274333882308138
åçå¨é¿ï¼18.84955592153876