java入门程序题及源码.doc

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1、一.实验目的了解接口，类，抽象类之间的不同，能够在其之间进行继承与实现掌握文件的输入输出流，包括scanner类，字符流，字节流等等的运用，能够对文件进行基本的读出写入二.实验内容实验题目一： 设计(1)形状接口、(2)积木块抽象类、(3)三角形类、正方形类、圆形类和矩形类，其中(2)实现了(1)，(3)继承了（2），然后编写主函数分别定义它们的对象，并显示其值。1．程序源代码publicclasstitle4_1{publicstaticvoidmain(String[]args){Shapecircle=newCircle(20),rect=newRectangle

2、(100,50);Shapesquare=newSquare(10),tri=newTriangle(10,20,25);circle.showArea();circle.showCircle();rect.showArea();rect.showCircle();square.showArea();square.showCircle();tri.showArea();tri.showCircle();}}//形状接口interfaceShape{publicdoublegetArea();//求面积publicdoublegetCircle();//求周长public

3、voidshowArea();publicvoidshowCircle();}//积木块抽象类abstractclassBuildingBlockimplementsShape{publicvoidshowArea(){}publicvoidshowCircle(){}}//圆类classCircleextendsBuildingBlock{privatedoubler;publicCircle(doubler){this.r=r;}//求面积publicdoublegetArea(){returnMath.PI*this.r*this.r;}//求周长publicdo

4、ublegetCircle(){return2*this.r*Math.PI;}publicvoidshowArea(){System.out.println("圆的半径为："+this.r);System.out.println("圆面积："+this.getArea());}publicvoidshowCircle(){System.out.println("圆周长："+this.getCircle());System.out.println();}}//定义长方形classRectangleextendsBuildingBlock{privatedoublel,w

5、;publicRectangle(doublel,doublew){this.w=w;this.l=l;}publicdoublegetArea(){returnthis.w*this.l;}publicdoublegetCircle(){return2*(this.w+this.l);}publicvoidshowArea(){System.out.println("长方形的长为："+this.l+"宽为："+this.w);System.out.println("长方形面积："+this.getArea());}publicvoidshowCircle(){Syst

6、em.out.println("长方形周长："+this.getCircle());System.out.println();}}//定义正方形classSquareextendsBuildingBlock{privatedoublea;publicSquare(doublea){this.a=a;}publicdoublegetArea(){returnthis.a*this.a;}publicdoublegetCircle(){return4*this.a;}publicvoidshowArea(){System.out.println("正方形的边长为："+thi

7、s.a);System.out.println("正方形面积："+this.getArea());}publicvoidshowCircle(){System.out.println("正方形周长："+this.getCircle());System.out.println();}}//定义三角形classTriangleextendsBuildingBlock{privatedoublea,b,c,q;publicTriangle(doublea,doubleb,doublec){this.a=a;this.b=b;this.c=c;t