java类的继承与多态实验报告

1、实验报告课程名称面向对象程序设计实验名称实验三、类的继承与多态日期2018/4/23学生学号姓名班级实验目的：通过本次实验，要求学生能进一步掌握继承和多态的概念，熟练定义类、派生类、抽象类、抽象方法、虚拟方法和重载方法。实验条件：电脑一台、能上网查阅资料。首先定义基本几何图形的基类（ Shape），然后定义Shape 的派生类Circle(形 ) 、 Square （正方形）和Triangle(三角形 ) 。要求通过方法覆盖来计算各圆种图形的面积和周长。(提示:求三角形的面积用海伦公式：SL * (L a) * (L b) * ( L c) ，其中 a,b,c是三角形的边长，L=(a+b+c)

2、/2 ，即周长的一半。 )源代码：packagepublicabstractclassprotectedStringpublicShape()name= " 图形类 " ;Shape name;publicShape(Stringsuper ();this. name=name;name)publicString getName() returnname;publicvoidsetName(Stringname) this. name =name;abstractdoublearea();abstractdoublelength();publicString toStrin

3、g() / TODOAuto-generated method stubreturnname+": 周长和面积分别是" +length()+","+area();精选文库packagepublicclassSquareextendsShape privatedoublea;publicSquare(doublea,Stringname)super ( name);this. a= a;doublearea() / TODO Auto-generated method stubreturnMath.pow( a, 2);doublelength() / T

4、ODO Auto-generated method stub return 4* a;packagepublicclassCircleextendsShape privatedoubler ;publicCircle(doubler ,Stringname)super ( name);this. r = r ;doublearea() / TODO Auto-generated method stubreturnMath.PI *Math.pow( r , 2);doublelength() 2精选文库/ TODO Auto-generated method stubreturn2*Math.

5、PI * r ;packagepublicclassTriangleextends Shape privatedoublea;privatedoubleb;privatedoublec ;publicTriangle (doublea, doubleb, doublec ,Stringname)super ( name);this. a= a;this. b= b;this. c = c;doublearea() doubleL=( a +b+c )/2;/ TODO Auto-generated method stubreturnMath.sqrt( L*(L- a )*(L- b)*(L

6、- c);doublelength() / TODO Auto-generated method stubdoubleL=( a +b+c )/2;return2* L;3精选文库packageruanjian.zhaihaiyang.shiyan3;publicclassShapeDemo publicstaticvoidmain(Stringargs ) Shape s1 =null ;s1=new Circle(5,"圆形");System.out .println(s1 .toString();s1=new Square(6,"正方形");System.out .println(s1 .toString();s1=new Triangle(3, 4, 5,"三角形 ");System.out .println(s1 .toString();实