Encapsulation, inheritance, and polymorphism of Java's------class (i)

problem:① Perfect The set () method to ensure that the correct date value ( legitimacy )is obtained;

② combines the tomorrow () and yestoday () methods into the following daysafter ( ) methods and adds some methods:

public int Getweek ()// returns the day of the week for the current date, ranging from 0to6

public string toweekstring ()// returns the Chinese string for the day of the week for the current date

Public b Oolean before (mydate D)// determine whether before the specified date

public int Daysbetween (mydate D)//returns the number of days between the current date and the date D

Public b Oolean equals (Object obj)// compares two objects for equality

Import Java.util.calendar;import Java.util.scanner;public class MyDate2 {int year,month,day;    Boolean iscorrect=true;      private static int thisyear; static {Thisyear=calendar.getinstance (). get (Calendar.year);//Gets the year value in the current date object} public MyDate2 (int years, int mo      nth, int day) {This.set (year, month, day);                          } public MyDate2 () {this (1970,1,1);    Call other constructed methods declared by this class} public MyDate2 (MyDate2 d) {this.set (d);    } public void set (int y, int. m, int d) {if (y<1) {System.out.println ("Input year is ERROR!!!");    This.iscorrect=false;    return; }if (m<1| |    M&GT;12) {System.out.println ("Input Month is ERROR!!!");    This.iscorrect=false;    return;    } if (Day<=0 | | day>daysofmonth ()) {System.out.println ("Input Day is ERROR!!!");    This.iscorrect=false;    return;                                 } this.year = y;        This.month = m;    This.day = D; } public void Set (MyDate2 d) {set (D.year, D.month, D.day);    Call member method with the same name, cannot use this ()} public String toString () {return this.year+ "year" +this.month+ "month" +this.day+ "Day";                         } public static int getthisyear () {return thisyear; Access static member variable} public static Boolean isleapyear (int year) {return year%400==0 | | year%100!=0 && year%    4==0;            } public boolean isleapyear () {return isleapyear (this.year);         Call static Method} public Boolean equals (MyDate2 D) {//this refers to the current object calling this method return This==d | |    D!=null && this.year==d.year && this.month==d.month && this.day==d.day; The public boolean equals (object obj) {if (this==obj)//this refers to the object that invokes the current method re        Turn true;              if (obj instanceof MyDate2) {MyDate2 d = (MyDate2) obj; Type cast return this.year==d.year&& this.month==d.month && This.day==d.day;    } return false;        } public static int daysofmonth (int year, int month) {switch (month)//calculates the number of days per month             {Case 1:case 3:case 5:case 7:case 8:case 10:case 12:return 31;            Case 4:case 6:case 9:case 11:return 30;            Case 2:return isleapyear (year)? 29:28;        Default:return 0;    }} public int daysofmonth () {return daysofmonth (this.year, this.month);                              } public void Tomorrow () {this.day++;            Changing the value of the current object through this, there is no return value if (Day>this.daysofmonth ()) {day=1;            month++;                if (month>12) {month=1;            year++;             }}} public MyDate2 Yestoday () {MyDate2 yes=new MyDate2 (this);        Executes the copy construction method, creates a new instance, and does not change the current object this yes.day--;     if (yes.day==0) {       yes.month--;                if (yes.month==0) {yes.month=12;            yes.year--;        } Yes.day = Daysofmonth (Yes.year, yes.month);                              } return yes;             Return object reference} public MyDate2 dayafter (int n) {MyDate2 yes=new MyDate2 (this);        Executes the copy construction method, creates a new instance, and does not change the current object this yes.day+=n;            if (yes.day==0) {yes.month--;                if (yes.month==0) {yes.month=12;            yes.year--;        } Yes.day = Daysofmonth (Yes.year, yes.month);        SYSTEM.OUT.PRINTLN ("* *" +yes.year+ "" +yes.month+ "" +yes.day ");        return yes;            } if (Yes.day>this.daysofmonth ()) {yes.day=1;            yes.month++;                if (yes.month>12) {yes.month=1;            yes.year++;                              }} return yes; Return object reference} public int getsumdays (MyDate2 d) {iNT Sum=0;    for (int i=1;i<d.year;i++) {sum+=d.isleapyear (i)? 366:365;    } for (int i=1;i<d.month;i++) {sum+=d.daysofmonth (d.year,i);    } Sum+=d.day;    return sum;    } public int Getweek () {long sum=0;    Int week;    for (int i=1;i<this.year;i++) {sum+=this.isleapyear (i)? 366:365;    } for (int i=1;i<this.month;i++) {sum+=this.daysofmonth (this.year,i);    } Sum+=this.day;    week= (int) sum%7;    Return week;    } public String toweekstring () {switch (Getweek ()) {case 0:return "Sunday";    Case 1:return "Monday";    Case 2:return "Tuesay";    Case 3:return "Wednesday";    Case 4:return "Thursday";    Case 5:return "Friday";    Default:return "Saturday";    }} public Boolean before (MyDate2 D) {if (this.year<d.year) {return true;    }else if (this.year==d.year) {if (This.month<d.month) {return true;    }else if (this.month==d.month) {if (This.day<d.day) {return true; }else{REturn false;    }}else{return false;    }}else{return false;    }} public int daysbetween (MyDate2 d) {int a=getsumdays (d);    int b=getsumdays (this);    Return Math.Abs (A-B);   }}class mydate_ex{public static void Main (String args[]) {Scanner sc=new Scanner (system.in);    SYSTEM.OUT.PRINTLN ("Please input date:");         while (Sc.hasnext ()) {MyDate2 d= new MyDate2 (Sc.nextint (), Sc.nextint (), Sc.nextint ());        if (d.iscorrect) {System.out.println ("If you want to konw yestoday date,please input-1");        System.out.println ("or Tomorrow Date,please input 1");        System.out.println (D.dayafter (Sc.nextint ()));        System.out.println ("Week:" +d.getweek () + "" +d.toweekstring ());        System.out.println ("Input a cmparative Date:");        MyDate2 r=new MyDate2 (Sc.nextint (), Sc.nextint (), Sc.nextint ());        System.out.println (D.before (R));        System.out.println ("Date_d between Date_r has" +d.daysbetween (r) + "Days");     }   System.out.println ();    SYSTEM.OUT.PRINTLN ("Please input date:"); }    }}

Encapsulation, inheritance, and polymorphism of Java's------class (i)