题目显示不全，完整题目描述：

（1）定义闭合图形抽象类ClosedFigure定义属性：1.形状；2.定义构造方法，给形状赋值；3.定义两个抽象方法：计算面积和计算周长；4.定义一个显示方法：显示图像形状，周长，面积；（2）定义ClosedFigure的子类椭圆Ellipse定义属性：1.长短轴定义构造方法：初始化长短轴；2.实现从父类继承来的抽象方法；[提示：椭圆求周长公式Math.PI*(this.radius_a+this.radius_b)]（3）定义ClosedFigure的子类矩形类Rectangle定义属性：1.长和宽定义构造方法：初始化长和宽；2.实现从父类继承来的抽象方法；

完整代码如下:

package naizi;

import java.util.Scanner; 

//闭合图形抽象类

abstract class ClosedFigure{

public String shape;

public ClosedFigure(String shape){

	this.shape=shape;

}

abstract double perimeter();

abstract double area();

public void print()               //显示形状、属性、周长及面积

{

    System.out.println("this is a "+this.shape+",perimeter:"+this.perimeter()+",area:"+this.area());

}

}

//定义椭圆类

class Ellipse extends ClosedFigure{

double Longaxis,Shortaxis;

public Ellipse(String shape) {

	super(shape);

}

public Ellipse(double a,double b) {

	this("Ellipse");

	this.Longaxis=a;

	this.Shortaxis=b;

}

double perimeter(){

	return Math.PI*(this.Longaxis+this.Shortaxis);

}

double area(){

	return Math.PI*this.Longaxis*this.Shortaxis;

}

}

//定义矩形类

class Rectangle extends ClosedFigure{

double Length,Width;

public Rectangle(String shape) {

	super(shape);

}

public Rectangle(double a,double b) {

	this("Rectangle");

	this.Length=a;

	this.Width=b;

}

double perimeter(){

	return 2*(this.Length+this.Width);

}

double area(){

	return this.Length*this.Width;

}

}

public class ClosedFigure_ex

{

public static void main(String args[]){

	int a,b;

	ClosedFigure d1;

	ClosedFigure d2;

	try{

		Scanner sc = new Scanner(System.in);

		String str1 = sc.next();

		a=Integer.parseInt(str1);

		str1 = sc.next();

		b=Integer.parseInt(str1);

		d1=new Ellipse(a,b);

		d1.print(); 

		String str2 = sc.next();

		a=Integer.parseInt(str2);

		str2 = sc.next();

		b=Integer.parseInt(str2);

		d2=new Rectangle(a,b);

		d2.print();

		} catch(Exception e){

			System.out.println("error");

			}

}

}

测试如下: