继承性 练习 圆柱

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继承性 练习 圆柱

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package com.atgui.exer1;
/*
 * 在CylinderTest类中创建Cylinder类的对象，设置圆柱的底面半径和高，并输出圆柱的体积。
 */
public class Circle
{
	private double radius; //圆的半径
	public Circle() {
		radius = 1.0;
	}
	public void  setRadius(double radius) {
		this.radius = radius;
	}
	public double getRadius() {
		return this.radius;
	}
	
	public double findArea() {
		return Math.PI*this.radius*this.radius;
	}
}

package com.atgui.exer1;

public class Cylinder extends Circle
{
	private double length;//高
	
	public Cylinder() {
		length = 1;
	}
	public void setLength(double lenght) {
		this.length = lenght;
	}
	public double getLength() {
		return this.length;
	}
	
	public double findVolume() {
/*		return Math.PI*getRadius()*getRadius()*getLength();		*/
		return findArea() * getLength();
	}
}

package com.atgui.exer1;

public class CylinderTest
{
	public static void main(String[] args)
	{
		Cylinder cy = new Cylinder();
		cy.setRadius(2.1);
		cy.setLength(3.4);
		double volume = cy.findVolume();
		System.out.println("圆柱的体积为" + volume);
		
		double area = cy.findArea();
		System.out.println("圆柱底面的面积为" + area);
	}
}