面向对象编程.doc

-seeker-面向对象编程【成员变量的封装】通过get和set方法进行取值和赋值：class Human/成员属性都是私有的private String name ;private String sex ;private int age ;public String getName()return name ;public void setName(String name) = name ;/省略其他变量的set和get方法public void work()System.out.println(“work”) ;public class HumanDemopublic static void main(String args)Human jim = new Human() ;/设置成员变量的值jim.setName(“Jim”) ;jim.setAge(20) ;System.out.println(“Age : ”+ jim.getAge() ;输出结果：Age：20（eclipse中提供智能实现变量成员的get和set方法）【成员变量的继承】1. public成员变量：任何子类都可以继承它。public class FatherClasspublic String str1 = “父类属性”；class SonClass extends FatherClassvoid()SonClass son = new SonClass() ;System.out.prinln(“在子类的方法中继承”) ;/子类对象继承父类的属性str1System.out.prinln(son.str1) ;public class Demopublic static void main(String args)/创建子类对象SonClass son = new SonClass() ;/调用相关方法son.print() ;2. protected成员变量它的子类可以访问该变量，子类与父类可以处于不同的包内。package pac1 /父类所在包public class FatherClasspublic String str1 = “父类的公共属性”;protected String str2 = “父类的受保护属性”;package pac2 /所在包不同于FatherClass类import pac1.FatherClass ;public class SonClass extends FatherClassvoid print()SonClass son = new SonClass() ;System.out.println(“在子类的方法中：”) ;System.out.println(son.str2) ;package pac2 /与子类在同一个包内public class DemoClasspublic static void main(String args)SonClass son2 = new SonClass() ;son.print() ;3. 默认修饰符成员变量包外的子类不能访问它，包内的类可以继承。package pac1 /父类所在包public class FatherClassString str3 = “父类（默认修饰符）的属性”;/同一个包内其他类可以继承“父类”public class Demopublic static void main(String args)FatherClass fc = new FatherClass() ;fc.print() ;/其他包的类访问父类（默认修饰符）的对象package pac2import pac1.FatherClasspublic class WrongClass extends FatherClassWrongClass wr = new WrongClass() ;/该语句编译错误System.out.println(wr.str3) ;4. private成员变量不允许任何子类继承。【成员变量的隐藏】class FatherString str = “父类的成员变量”;class Son extends FatherString str = “子类的成员变量”;void show()/通过super（关键字）访问父类成员变量System.out.println(super.str) ;public class Hiddenpublic static void main(String args)/创建子类对象Son son = new Son() ;/调用子类的方法son.show() ;【利用GregorianCalendar类编写日历】import java.util.* ;public class MyCalendarpublic static void main(String args)GregorianCalendar now = new GregorianCalendar() ;Date date = new Date() ;System.out.println(date.toString() ;/用date设置now的时间now.setTime(date) ;int today = now.get(Calendar.DAY_OF_MONTH) ;int month = now.get(Calendar.MONTH) ;/初始化now的日期为1now.set(Calendar.DAY_OF_MONTH , 1) ;/得到now是一周的第几天int week = now.get(Calendar.DAY_OF_WEEK) ;System.out.println(“Sun Mon Tue Wed Thu Fri Sat”) ;for(int i = Calendar.SUNDAY ; i week ; i+)System.out.prin(“ ”) ;while(now.get(Calendar.MONTH) = month)int day = now.get(Calendar.DAY_OF_MONTH) ;if(day 10)if(day = today)System.out.print(“-”+ day +“-”)elseSystem.out.print(“ ”+ day +“ ”)elseif(day = today)System.out.print(“-”+ day +“-”)elseSystem.out.print(“ ”+ d