刚看了一个程序，并写了一下，然后用Java 再写了一下

C# 的源码是这样的：

using System;

namespace Date

{

    class Date

    {

        private int month;

        private int day;

        private int year;

        public Date(int themonth,int theday,int theyear)

        {

            if (themonth > 0 && themonth <= 12)

                month = themonth;

            else

            {

                month = 1;

                Console.Write("Month {0} invaild. Set to month 1", themonth);

            }

            year = theyear;

            day = CheckDay (theday);

        }

        private int CheckDay(int testday)

        {

            int[] days = {0,31,28,31,30,31,30,31,31,30,31,30,31};

            if (testday > 0 && testday <= days[month])

            {

                return testday;

            }

            if (month == 2 && month == 29 && (year % 400 == 0 || (year % 100 != 0 && year % 4 == 0)))

                return testday;

            Console.Write("Day {0} invaild. Set to day 1.", testday);

            return 1;

        }

        public string ToDateString()

        {

            return month + "/" + day + "/" + year;

        }

    }

}

using System;

namespace Date

{

    class Employee

    {

        private string firstname;

        private string lastname;

        private Date birthday;

        private Date hireday;

        public Employee(string first,string last,int birthMonth,

            int birthDay,int birthYear,int hireMonth,int hireDay,

                int hireYear)

        {

            firstname = first;

            lastname = last;

            birthday = new Date(birthMonth, birthDay, birthYear);

            hireday = new Date(hireMonth, hireDay, hireYear);

        }

        public string ToEmployeeString()

        {

            return lastname + "  " + firstname + " /n" +

                "Hired : " + hireday.ToDateString() +

                "/nBirthday : " + birthday.ToDateString();

        }

    }

}

using System;

namespace Date

{

    class CompositionTest

    {

        static void Main(string[] args)

        {

            Employee e = new Employee("Bob", "chen", 12, 11, 1990, 11, 21, 2010);

            string output = e.ToEmployeeString();

            Console.Write(output);

            Console.ReadKey();

        }

    }

}

Java 的源码是这样的：

import java.applet.*;

public class Date {

 private int month;

 private int day;

 private int year;

 

 public Date(int themonth,int theday,int theyear)

 {

  if(themonth > 0 && themonth <= 12)

   month = themonth;

  year = theyear;

  day = CheckDay(theday);

 }

 

 private int CheckDay(int testDay)

 {

  int[] DaysofMonth = {0,31,28,31,30,31,30,31,31,30,31,30,31};

  if(testDay > 0 && testDay <= DaysofMonth[month])

   return testDay;

  if(month==2 && testDay==29 && ((year%400==0)||(year%4==0 && year%100!=0)))

    return testDay;

  System.out.println("Day" + testDay + "invaild . Set to day 1.");

  return 1;

 }

 

 public String ToDateString()

 {

  return month + "/" + day + "/" + year;

 }

}

import java.applet.*;

public class Employee {

 private String firstname;

 private String lastname;

 private Date birthDate;

 private Date hireDate;

 

 public Employee(String first,String last,int BMonth,int BDay,int BYear,

   int HMonth,int HDay,int HYear)

 {

  firstname = first;

  lastname = last;

  birthDate = new Date(BMonth,BDay,BYear);

  hireDate = new Date(HMonth,HDay,HYear);

 }

 

 public String ToEmployeeString()

 {

  return lastname + "   " + firstname + "/n" +

  "Hired : " + hireDate.ToDateString() +

  "/nBirthDay : " + birthDate.ToDateString();

 }

}

import java.applet.*;

public class CompositionTest {

 public static void main(String[] args) {

  Employee e = new Employee("Bob","Chen",12,21,1899,11,5,2007);

  

  System.out.print(e.ToEmployeeString());

 }

}

最后我发现，其实两者没啥大的区别。不过中间在写Java 的时候还是遇到了麻烦、

在C#  中，String  和  string   这两个单词，是不一样的。表达不同的意思， 要分开用。

但是在Java  中，就只有 String  这一个。哪都通用！！