需要 Java 中的属性方面的帮助

Question

我要做的是访问一个对象，在本例中为 date1，它有 3 个属性日、月和年。我正在尝试创建一个名为 showTomorrow() 的方法，它将以字符串格式显示对象信息 1 天。这意味着我无法更改原始对象的属性。

我已经编写了 Data.java 程序，它如下所示，如果有人能指出正确的方向或告诉我它真正有用的地方。

我相信这就是我在主要方法上运行的基本方法。

**Date date1 = new Date(30, 12, 2013)** // instantiate a new object with those paramaters

**date1.showDate();** // display the original date

**date1.tomorrow();** // shows what that date would be 1 day infront

问题是现在它没有显示任何内容。我想通过说 dayTomorrow = this.day++;我将它的默认值 + 1 天添加到变量 dayTomorrow。

public class Date
{
    private int day;
    private int month;
    private int year;
    private int dayTomorrow;
    private int monthTomorrow;
    private int yearTomorrow;

    public Date()
    {
            day = 1;
            month = 1;
            year = 1970;
    }
    public Date(int inDay, int inMonth, int inYear)
    {
            day = inDay;
            month = inMonth;
            year = inYear;
    }
    public void setDate(int inDay, int inMonth, int inYear)
    {
            day = inDay;
            month = inMonth;
            year = inYear;
    }
    public String getDate()
    {
            String strDate;
            strDate = day + "/" + month + "/" + year;
            return strDate;
    }
    public String getTomorrow()
    {
            String strTomorrow;
            strTomorrow = dayTomorrow + "/" + monthTomorrow + "/" + yearTomorrow;
            return strTomorrow;
    }
    public String tomorrow()
    {
            dayTomorrow = this.day++;
            monthTomorrow = this.month;
            yearTomorrow = this.year;

            if(dayTomorrow > 30)
            {
                    dayTomorrow = 1;
                    monthTomorrow = this.month++;
            }
            if(monthTomorrow > 12)
            {
                    monthTomorrow = 1;
                    yearTomorrow = this.year++;
            }

            return getTomorrow();
    }
    public void showDate()
    {
            System.out.print("\n\n THIS OBJECT IS STORING ");
            System.out.print(getDate());
            System.out.print("\n\n");
    }
    public void showTomorrow()
    {
            System.out.print("\n\n THE DATE TOMORROW IS ");
            System.out.print(getTomorrow());
            System.out.print("\n\n");
    }
    public boolean equals(Date inDate)
    {
            if(this.day == inDate.day && this.month == inDate.month && this.year == inDate.year)
            {
                    return true;
            }
            else
            {
                    return false;
            }
    }
}

Answer 1

您只需要使用++this.day、++this.month 和++this.year。当您使用this.day++ 时，它会返回以前的日期值，而不是新的。将++ 放在前面即可解决问题。此外，它还会更改 day 值...您可能希望将其更改为 this.day + 1。

Answer 2

你是在 date1.tomorrow() 之后调用 showDate() 来显示你的输出吗？

或者代替date1.tomorrow();调用date1.showTomorrow();

Answer 3

看看这个：http://docs.oracle.com/javase/tutorial/java/nutsandbolts/op1.html

后增量 ...

Answer 4

您可以在 java 中使用本机日期支持，但我认为您只是在练习，对吗？

这应该可以解决问题：

public class Date {
    private int day = 1;
    private int month = 1;
    private int year = 1970;
    private int dayTomorrow = day+1;
    private int monthTomorrow;
    private int yearTomorrow;

    public Date()
    {
            tomorrow();
    }
    public Date(int inDay, int inMonth, int inYear)
    {
            day = inDay;
            month = inMonth;
            year = inYear;
            tomorrow();
    }
    public void setDate(int inDay, int inMonth, int inYear)
    {
            day = inDay;
            month = inMonth;
            year = inYear;
    }
    public String getDate()
    {
            String strDate;
            strDate = day + "/" + month + "/" + year;
            return strDate;
    }
    public String getTomorrow()
    {
            String strTomorrow;
            strTomorrow = dayTomorrow + "/" + monthTomorrow + "/" + yearTomorrow;
            return strTomorrow;
    }
    public void tomorrow()
    {
            monthTomorrow = this.month;
            yearTomorrow = this.year;

            if(dayTomorrow > 30)
            {
                    dayTomorrow = 1;
                    monthTomorrow = this.month++;
            }
            if(monthTomorrow > 12)
            {
                    monthTomorrow = 1;
                    yearTomorrow = this.year++;
            }
    }
    public void showDate()
    {
            System.out.print("\n\n THIS OBJECT IS STORING ");
            System.out.print(getDate());
            System.out.print("\n\n");
    }
    public void showTomorrow()
    {
            System.out.print("\n\n THE DATE TOMORROW IS ");
            System.out.print(getTomorrow());
            System.out.print("\n\n");
    }
    public boolean equals(Date inDate)
    {
            if(this.day == inDate.day && this.month == inDate.month && this.year == inDate.year)
            {
                    return true;
            }
            else
            {
                    return false;
            }
    }
}

仔细查看我所做的任何更改；） 以下是主要内容：

public static void main(String[] args) {
    Date d = new Date();
    d.showDate();
    d.showTomorrow();
}