java - 在android studio中查找下周四的日期

Question

我正在尝试制作一个应用程序，其中包括告诉下周四的时间。每次我打开该类(class)时，应用程序都会崩溃。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_authorised);
    button.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            nextThursday();
        }
    });

}

void nextThursday(){
    String nextThursday = getNext(DayOfWeek.THURSDAY).format(DateTimeFormatter.ofPattern("MMM, dd yyyy", Locale.ENGLISH));
    nextThurs.setText(nextThursday);
}

public static LocalDate getNext(DayOfWeek dayOfWeek) {
    // get the reference day for the word "next" (that is the current day)
    LocalDate today = LocalDate.now();
    // start with tomorrow
    LocalDate next = today.plusDays(1);

    // as long as the desired day of week is not reached
    while (next.getDayOfWeek() != dayOfWeek) {
        // add one day and try again
        next = next.plusDays(1);
    }

    // then return the result
    return next;
}

}

有人可以帮忙吗？

Answer 1

此答案使用 java.time，这是自从 Joda Time 项目停止进一步开发以来要使用的日期时间 API。

它基本上使用了一种在 Joda Time 中也可以实现的算法，但我不知 Prop 体是否以及如何实现，所以我向您展示了一种在 java.time 中实现的方法。

定义一个返回一周中下一个给定日期的日期的方法:

public static LocalDate getNext(DayOfWeek dayOfWeek) {
    // get the reference day for the word "next" (that is the current day)
    LocalDate today = LocalDate.now();
    // start with tomorrow
    LocalDate next = today.plusDays(1);

    // as long as the desired day of week is not reached
    while (next.getDayOfWeek() != dayOfWeek) {
        // add one day and try again
        next = next.plusDays(1);
    }

    // then return the result
    return next;
}

并在 main() 中使用它只是为了打印出来:

public static void main(String[] args) {
    System.out.println("Next Thursday is " + 
            getNext(DayOfWeek.THURSDAY)
                .format(DateTimeFormatter.ofPattern("MMM, dd yyyy", Locale.ENGLISH)));
}

2020 年 5 月 15 日星期五执行时会产生输出:

Next Thursday is May, 21 2020

当然，格式只是一个示例，可以根据您的需要轻松调整。