我试图计算java中考虑了几个月的年龄,所以减去几年就不行了.我还想告诉用户今天是他们的生日.这是我到目前为止的代码,但我担心它有点偏.它也不会告诉今天是否是生日,即使它比较的两个日期是相等的.我试图最初计算的方式是使用毫秒.你看到获得当前日期的两种方法的原因是因为我正在尝试让它工作,但是想向每个人展示我的工作,以便他们能够指出我正确的方向.

编辑澄清
我的意思是2015-1993可以是22岁或21岁,这取决于他们今年的生日已经过去了.我想确保在考虑到这一点后得到正确的年龄.

public class ShowAgeActivity extends AppCompatActivity {

private TextView usersAge;

private static long daysBetween(Date one, Date two)
{
    long difference = (one.getTime()-two.getTime())/86400000; return Math.abs(difference);
}

private Date getCurrentForBirthday()
{
    Date birthday = (Date) this.getIntent().getExtras().get("TheBirthDay");
    int birthdayYear = birthday.getYear() + 1900;
    Calendar cal = Calendar.getInstance();
    cal.set(birthdayYear, Calendar.MONTH, Calendar.DAY_OF_MONTH);
    Date current = cal.getTime();
    return current;
}


protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_show_age);


    Date birthday = (Date) this.getIntent().getExtras().get("TheBirthDay");
      Date currentDay = Calendar.getInstance().getTime();

      long age = daysBetween(birthday,currentDay)/365;

      usersAge =(TextView)findViewById(R.id.ageTextView);

    if (birthday.compareTo(getCurrentForBirthday()) == 0 )
    {
        usersAge.setText("It is your birthday, and your Age is " + String.valueOf(age));
    }

    usersAge.setText("Your Age is " + String.valueOf(age));


    }

}

解决方法:

下面是一个如何计算一个人的年龄的例子,如果今天是他们的生日,以及如果今天不是他们的生日,那么使用新的java.time包类作为其中一部分包括Java 8.

  LocalDate today             = LocalDate.now();
  LocalDate birthday          = LocalDate.of(1982, 9, 26);
  LocalDate thisYearsBirthday = birthday.with(Year.now());

  long age = ChronoUnit.YEARS.between(birthday, today);

  if (thisYearsBirthday.equals(today))
  {
     System.out.println("It is your birthday, and your Age is " + age);
  }
  else
  {
     long daysUntilBirthday = ChronoUnit.DAYS.between(today, thisYearsBirthday);
     System.out.println("Your age is " + age + ". " + daysUntilBirthday + " more days until your birthday!");
  }