第三章类,对象和接口代码部分.doc

类、对象和接口程序代码例子1class XiyoujiRenwu float height,weight; String head, ear,hand,foot, mouth; void speak(String s) System.out.println(s); class A public static void main(String args) XiyoujiRenwu zhubajie; /声明对象 zhubajie=new XiyoujiRenwu(); /为对象分配内存，使用new 运算符和默认的构造方法 例子2class Point int x,y; Point(int a,int b) x=a; y=b; public class A public static void main(String args) Point p1,p2; /声明对象p1和p2 p1=new Point(10,10); /为对象分配内存，使用 new 和类中的构造方法 p2=new Point(23,35); /为对象分配内存，使用 new 和类中的构造方法例子3class XiyoujiRenwu float height,weight; String head, ear,hand,foot,mouth;void speak(String s) head=歪着头; System.out.println(s); class Example4_3 public static void main(String args) XiyoujiRenwu zhubajie,sunwukong;/声明对象 zhubajie=new XiyoujiRenwu(); /为对象分配内存 sunwukong=new XiyoujiRenwu(); zhubajie.height=1.80f; /对象给自己的变量赋值 zhubajie.head=大头; zhubajie.ear=一双大耳朵; sunwukong.height=1.62f; /对象给自己的变量赋值 sunwukong.weight=1000f; sunwukong.head=绣发飘飘; System.out.println(zhubajie的身高：+zhubajie.height); System.out.println(zhubajie的头：+zhubajie.head); System.out.println(sunwukong的重量：+sunwukong.weight); System.out.println(sunwukong的头：+sunwukong.head); zhubajie.speak(俺老猪我想娶媳妇); /对象调用方法 System.out.println(zhubajie现在的头：+zhubajie.head); sunwukong.speak(老孙我重1000斤，我想骗八戒背我); /对象调用方法 System.out.println(sunwukong现在的头：+sunwukong.head); 例子7class 梯形 float 上底,高; static float 下底;梯形(float x,float y,float h) 上底=x; 下底=y; 高=h; float 获取下底() return 下底; void 修改下底(float b) 下底=b; class Example4_7 public static void main(String args) 梯形 laderOne=new 梯形(3.0f,10.0f,20),laderTwo=new 梯形(2.0f,3.0f,10); 梯形.下底=200; /通过类名操作类变量 System.out.println(laderOne的下底:+laderOne.获取下底(); System.out.println(laderTwo的下底:+laderTwo.获取下底(); laderTwo.修改下底(60); /通过对象操作类变量 System.out.println(laderOne的下底:+laderOne.获取下底(); System.out.println(laderTwo的下底:+laderTwo.获取下底(); 例子8class Fibi public static long fibinacii(int n) long c=0; if(n=1|n=2) c=1; else c=fibinacii(n-1)+fibinacii(n-2); return c; public class Example4_8 public static void main(String args) System.out.println(Fibi.fibinacii(7); 例子9package tom.jiafei;public class PrimNumber public void getPrimnumber(int n) int sum=0,i,j; for(i=1;i=n;i+) for(j=2;ji/2) System.out.print( +i); public static void main(String args) PrimNumber p=new PrimNumber(); p.getPrimnumber(20); 例子10 Applet小应用程序的例子例子11import tom.jiafei.*; /引入包tom.jiafei中的类public class Example4_11 public static void main(String args) PrimNumber num=new PrimNumber();/用包tom.jiafei中的类创建对象 num.getPrimnumber(30); 例子12public class Example4_12 public static void main(String args) PrimNumber num=new PrimNumber();/要保证PrimNuber类和Example4_12类在同一目录中 num.getPrimnumber(120); Trangel.javapackage tom.jiafei;public class Trangle double sideA,sideB,sideC; boolean boo; public Trangle(double a,double b,double c) sideA=a; sideB=b; sideC=c; if(a+bc&a+cb&c+ba) System.out.println(我是一个三角形); boo=true; else System.out.println(我不是一个三角形); boo=false; public void 计算面积() if(boo) double p=(sideA+sideB+sideC)/2.0; double area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC) ; System.out.println(面积是:+area); else System.out.println(不是一个三角形,不能计算面积); public void 修改三边(double a,double b,double c) sideA=a; sideB=b; sideC=c; if(a+bc&a+cb&c+ba) boo=true; else boo=false; 例子13import tom.jiafei.Trangle;class Example4_13 public static void main(String args) Trangle trangle=new Trangle(12,3,1); trangle.计算面积(); trangle.修改三边(3,4,5); trangle.计算面积(); 例子14class Example4_14 private int money;Example4_14() money=2000; private int getMoney() return money; public static void main(String args) Example4_14 exa=new Example4_14();exa.money=3000;int m=exa.getMoney(); System.out.println(money=+m); 例子15class Father private int money; float weight,height; String head; void speak(String s) System.out.println(s); class Son extends Father String hand,foot; public class Example4_15 public static void main(String args) Son boy; boy=new Son(); boy.weight=1.80f; boy.height=120f; boy.head=一个头; boy.hand=两只手 ; boy.foot=两只脚; boy.speak(我是儿子); System.out.println(boy.hand+boy.foot+boy.head+boy.weight+boy.height); 例子16class Chengji float f(float x,float y) return x*y; class Xiangjia extends Chengji float f(float x,float y) return x+y ; public class Example4_16 public static void main(String args) Xiangjia sum; sum=new Xiangjia(); float c=sum.f(4,6); System.out.println(c); 例子17class Area float f(float r ) return 3.14159f*r*r; float g(float x,float y) return x+y; class Circle extends Area float f(float r) return 3.14159f*2.0f*r; public class Example4_17 public static void main(String args) Circle yuan; yuan=new Circle(); float length=yuan.f(5.0f); float sum=yuan.g(232.645f,418.567f); System.out.println(length); System.out.println(sum); 例子18class A final double PI=3.1415926; public double getArea(final double r) return PI*r*r; public class Example4_18 public static void main(String args) A a=new A(); System.out.println(面积：+a.getArea(100); 例子20class 动物 void cry() class 狗 extends 动物 void cry() System.out.println(汪汪.); class 猫 extends 动物 void cry() System.out.println(喵喵.); class Example4_20 public static void main(String args) 动物 dongwu; dongwu=new 狗(); dongwu.cry(); dongwu=new 猫(); dongwu.cry(); 例子23class Student int number;String name;Student() Student(int number,String name) this.number=number;=name; System.out.println(I am +name+ my number is +number); class Univer_Student extends Student boolean 婚否; Univer_Student(int number,String name,boolean b) super(number,name); 婚否=b; System.out.println(婚否=+婚否); public class Example4_23 public static void main(String args) Univer_Student zhang=new Univer_Student(9901,和晓林,false); 例子24class Sum int n; float f() float sum=0; for(int i=1;i=n;i+) sum=sum+i; return sum; class Average extends Sum int n; float f() float c; super.n=n; c=super.f(); return c/n; float g() float c; c=super.f(); return c/2; public class Example4_24 public static void main(String args) Average aver=new Average(); aver.n=100; float result_1=aver.f(); float result_2=aver.g(); System.out.println(result_1=+result_1); System.out.println(result_2=+result_2); 例子25interface Computable int MAX=100; int f(int x);class China implements Computable int number; public int f(int x) /不要忘记public关键字 int sum=0; for(int i=1;i=x;i+) sum=sum+i; return sum; class Japan implements Computable int number; public int f(int x) return 44+x; public class Example4_25 public static void main(String args) China zhang; Japan henlu; zhang=new China(); henlu=new Japan(); zhang.number=991898+Computable.MAX; henlu.number=941448+Computable.MAX; System.out.println(number:+zhang.number+求和+zhang.f(100); System.out.println(number:+henlu.number+求和+henlu.f(100); 例子26interface 收费 public void 收取费用();interface 调节温度 public void controlTemperature();class 公共汽车 implements 收费 public void 收取费用() System.out.println(公共汽车:一元/张,不计算公里数); class 出租车 implements 收费, 调节温度 public void 收取费用() System.out.println(出租车:1