(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;

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: