java - 如何根据出生日期准确计算 Java 中的年龄

Question

我正在尝试计算占月的 java 中的年龄，因此仅减去年是行不通的。我还想告诉用户今天是不是他们的生日。这是我到目前为止的代码，但恐怕有点偏离。即使它比较的两个日期相等，它也不会判断今天是否是生日。我最初尝试计算的方式是使用毫秒。你看到 2 种获取当前日期的方法的原因是因为我正在尝试让它工作，但想向所有人展示我的工作，以便他们可以为我指明正确的方向。

编辑澄清我的意思是 2015-1993 可以是 22 岁或 21 岁，具体取决于他们今年的生日是否已经过去。考虑到这一点，我想确定我得到了正确的年龄。

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));


    }

Answer 1

下面是一个例子，说明如何计算一个人的年龄，如果今天是他们的生日，以及如果今天不是他们的生日，还需要多少天才能使用新的 java.time 包类包含在Java 8 的一部分。

  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!");
  }