Question

java,面向对象程序设计？

Answer 1

做好了，参考如下
public interface Shape {
public static final double PI = 3.14;
double getGirth();
double getArea();
}

public class Area {
double getShapeGrith(Shape shp) {
return shp.getGirth();
}
double getShapeArea(Shape shp) {
return shp.getArea();
}
}

public class Circle implements Shape {

private double radius;

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

@Override
public double getGirth() {
return 2*PI*radius;
}

@Override
public double getArea() {
return PI*radius*radius;
}
}

public class Rectangle implements Shape {

private double width;
private double height;

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

@Override
public double getGirth() {
return 2*(width+height);
}

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

追答

public class ShapeTest {

public static void main(String[] args) {
//创建一个圆
Area area = new Area();
Circle c = new Circle(2.0d);
System.out.println("圆的面积:"+area.getShapeArea(c));
System.out.println("圆的周长:"+area.getShapeGrith(c));
//创建一个矩形
Rectangle rect = new Rectangle(2d,5d);
System.out.println("矩形的面积:"+area.getShapeArea(rect));
System.out.println("矩形的周长:"+area.getShapeGrith(rect));
}

}

这是测试类

Answer 2

先做一个抽象类，然后把需要的抽象方法都写进去，再建两个下面的两个类，把抽象方法全部实现。接口和抽象类类似，写上方法，后面去实现，主函数直接用打印的方法出结果。
abstract class name{}
interface name{}
然后写抽象方法就行了

Answer 3

看看以后找工作了能不能请教别人哈