JAVA 程序设计题解与上机指导（第四版） 第二章·标识符、关键字和数据类型 2.12

/*2.12
设计实现一个MyGraphic类及子类，它们代表一些基本图形，这些图形包括矩形、三角形、圆、椭圆、菱形、梯形等。
试给能描述这些图形所必需的属性及必要的方法
**/
public class MyGraphic {
	String lineColor;//线条颜色
	String fillColor;//填充颜色
	MyGraphic(String lc,String fc){//图形构造方法
		this.lineColor=lc;
		this.fillColor=fc;
	}

	void print()
	{ System.out.println("line color is "+this.lineColor+"\t fill color is "+this.fillColor); }

	public static void main(String args[]){
		float rd=(float)4.5;
		MyCircle mc =new MyCircle(rd,"black","white");//定义“黑边白心”圆
		MyRectangle mr =new MyRectangle(4,6,"red","blue");//定义“红边蓝边”矩形
		MyEllipse me=new MyEllipse(3,4,"green","gray");

		System.out.println("Circle info: ");
		mc.print();
		System.out.println("circumference is "+mc.calCircum());//圆周长
		System.out.println("square is "+mc.calSquare());//圆面积
		
		System.out.println("Rectangle info: ");
		mr.print();
		System.out.println("circumference is "+mr.calCircum());//矩形周长
		System.out.println("square is "+mr.calSquare());//矩形面积

		System.out.println("Ellipse info: ");
		me.print();
		System.out.println("circumference is "+me.calCircum());//矩形周长
		System.out.println("square is "+me.calSquare());//矩形面积
	}


}

	
    class MyRectangle extends MyGraphic{
    	float rLong;
    	float rWidth;
    	MyRectangle (float rl, float rw, String lc, String fc){
    		super(lc,fc);
    		this.rLong=rl;
    		this.rWidth=rw;
    	}
    	
    	float calCircum(){
    		return ((float)((this.rLong+this.rWidth))*2);
    	}
    	float calSquare(){
    		return ((float)(this.rLong*this.rWidth));
    	}
    };
    
    class MyCircle extends MyGraphic{
    	float radius;
    	float rWidth;
    	MyCircle (float rd,String lc, String fc){
    		super(lc,fc);
    		this.radius=rd;
    	}
    	
    	float calCircum(){
    		return ((float)(this.radius*3.14*2));
    	}
    	float calSquare(){
    		return ((float)(this.radius*this.radius*3.14));
    	}
    };

    class MyEllipse extends MyGraphic{
    	float ra;
    	float rb;
    	MyEllipse (float a,float b,String lc,String fc){
    		super(lc,fc);
    		this.ra=a;
    		this.rb=b;
		}

		float calCircum(){// L=2πb+4(a-b
		return ((float)(this.rb*2*3.14+4*(this.ra-this.rb)));}
		float calSquare(){return ((float)(this.ra*rb*3.14));}
		};