package?com.lee.poly;
/*Shape類*/

public?abstract?class?Shape?{
	public?abstract?double?size();
	public?abstract?double?boundry();
}

Rectangle類：

package?com.lee.poly;

public?class?Rectangle?extends?Shape{
	public?double?len;
	public?double?hei;
	
	public?Rectangle(double?len,?double?hei)?{
		super();
		this.len?=?len;
		this.hei?=?hei;
	}
	
	public?void?setLen(double?len)?{
		this.len?=?len;
	}

	public?void?setHei(double?hei)?{
		this.hei?=?hei;
	}



	@Override
	public?double?size()?{
		double?size?=?len?*?hei;
		return?size;
	}

	@Override
	public?double?boundry()?{
		double?bou?=?(len?+?hei?)?*?2;
		return?bou;
	}

}

Circle類：

package?com.lee.poly;

public?class?Circle?extends?Shape{
	public?double?r;
	public?static?double?pi?=?3.14;
	
	public?Circle(double?r)?{
		super();
		this.r?=?r;
	}

	public?void?setR(double?r)?{
		this.r?=?r;
	}

	@Override
	public?double?size()?{
		double?size?=?pi?*?r?*?r;
		return?size;
	}

	@Override
	public?double?boundry()?{
		double?bou?=?2?*?pi?*?r;
		return?bou;
	}

}

測(cè)試類：

package?com.lee.poly;

import?java.util.Scanner;

public?class?Test?{

	public?static?void?main(String[]?args)?{
		Scanner?scan?=?new?Scanner(System.in);
		System.out.println("請(qǐng)輸入長(zhǎng)方形的長(zhǎng)：");
		double?len?=?scan.nextDouble();
		System.out.println("請(qǐng)輸入長(zhǎng)方形的寬：");
		double?hei?=?scan.nextDouble();
		Rectangle?rect?=?new?Rectangle(len,?hei);
		System.out.println("長(zhǎng)方形的面積是："?+?rect.size());
		System.out.println("長(zhǎng)方形的周長(zhǎng)是："?+?rect.boundry());
		
		System.out.println("請(qǐng)輸入圓形的半徑：");
		double?r?=?scan.nextDouble();
		Circle?cir?=?new?Circle(r);
		System.out.println("圓形的面積是："?+?cir.size());
		System.out.println("圓形的周長(zhǎng)是："?+?cir.boundry());
		scan.close();
	}

}

結(jié)果：

請(qǐng)輸入長(zhǎng)方形的長(zhǎng)：
12
請(qǐng)輸入長(zhǎng)方形的寬：
6
長(zhǎng)方形的面積是：72.0
長(zhǎng)方形的周長(zhǎng)是：36.0
請(qǐng)輸入圓形的半徑：
6
圓形的面積是：113.03999999999999
圓形的周長(zhǎng)是：37.68