继承性与Object类.docVIP

Java语言程序设计 实验报告 实验4继承性与Object类 1.实验内容 编写一个代表圆柱体的Cylinder类，该类是Circle类的子类。Cylinder类包括圆柱体的高度变量height以及计算圆柱体的体积方法volume()和计算表面积的方法surfaceArea()。 编写测试Cylinder类的CylinderTest类，并在该类得main方法中调用Cylinder类的相关方法。 package p; class Circle { float radius; Circle() { radius=0; } double area() { return radius*radius*Math.PI; } } import p.Circle class Cylinder extends Circle{ float height; Cylinder() {radius=1; height=2; } double volume() {Cylinder v=new Cylinder(); return height*v.area(); } double surfaceArea(){ Cylinder v=new Cylinder(); return 2*v.area()+2*Math.PI*radius; } } public class CylinderTest{ public static void main(String args[]){ Cylinder v=new Cylinder(); System.out.println(v.volume()); System.out.println(v.surfaceArea()); } } 运行结果： E:\javaxuejavac -d . Circle.java E:\javaxuejavac CylinderTest.java E:\javaxuejava CylinderTest 6.283185307179586 12.566370614359172 重写Point和Circle类的equals()、toString()方法，并测试这些方法的正确性。 class Point{ int x,y; Point(int x,int y) { this.x=x; this.y=y; } boolean equals(Point p) {if((this.x==p.x)(this.y==p.y))return true; else return false; } public String toString(){ return x=+x+ y=+y; } } public class P { public static void main(String args[]) { Point p1=new Point(1,2); Point p2=new Point(10,2); Point p3=new Point(1,2); System.out.println(p1.equals(p2)); System.out.println(p1.toString()); } } 运行结果： E:\javaxuejavac P.java E:\javaxuejava P false x=1 y=2 圆类： class Point{ public int x,y; Point(int xx,int yy){ x=xx; y=yy;} Point() { x=0; y=0; }} class Circle{ Point center; int radius; Circle() { center=new Point(); radius=1; }Circle(int xx,int yy,int r) { center=new Point(xx,yy); radius=r; } Circle(Point c,int r) { center=c; radius=r; } public boolean equals(Circle c) {if((c.center.x==this.center.x)(c.center.y==this.center.y) (c.radius==this.radius))return true; else return false; } public String toString(){ return x=+this.center.x+ y=+this.center