抽象类继承的使用-计算图形的周长和面积

先写出抽象类

/**
 * 图形类，抽象类
 * @author Administrator
 *
 */
public abstract class Shape {
	//计算图形周长方法
	public abstract double calcRound();
	//计算图形面积方法
	public abstract double calcArea();	
	
}

 再写出下面被继承的子类方法，通过重写父类的方法继承

//圆类，继承图形类
public class Yuan extends Shape{
        //特定属性-半径
	private double r;
	
	public  Yuan(double r){
		 = r;
	}
        //周长
        @Override
	public double calcRound(){
		return 2 *  *r;
	}
        //面积
        @Override
	public double calcArea(){
		return  * r * r;
	}
		
}

 

//三角形类
public class Sanjiaoxing {

	private double borderA;
	private double borderB;
	private double borderC;//底边
	private double height;//高
	
	public Sanjiaoxing(double borderA, double borderB, double borderC, double height) {
		super();
		 = borderA;
		 = borderB;
		 = borderC;
		 = height;
	}
        @Override
	public double calcRound(){
		return borderA + borderB + borderC;
	}
        @Override
	public double calcArea(){
		return borderC * height / 2;
	}
	
}

//矩形类
public class JuXing extends Shape{

	private double width;
	private double height;
	
	public JuXing(double width, double height) {
		super();
		 = width;
		 = height;
	}

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

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

//测试类
public class Test {

	public static void main(String[] args) {
		Sanjiaoxing s = new Sanjiaoxing(5,4,3,4);
		(());
		(());
		
		Yuan y = new Yuan(5);
		(());
		(());

		JuXing j = new JuXing(5,10);
		(());
		(());
	}

}