java计算经过的时间？

Question

我想知道如何实现这样的目标：

在活动B中，用户将键入内容并按下按钮返回到活动A。在活动A中，它将显示几秒钟前的。如果状态为一小时前，则将显示一小时前

如何实现

Answer 1

你可以这样做

 long startTime
 long duration

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    startTime = SystemClock.uptimeMillis();
} 




 @Override
public void onBackPressed() {
    duartion = SystemClock.uptimeMillis() - startTime;
    //Duration you get in MS
    once you are done call 
    super.onBackPressed();//finish the activity

} 

Answer 2

下面是一个不使用java的工作代码。时间LocalDateTime 如果您想使用它，可以进行必要的更改

您可以使用共享首选项在活动A中节省时间。

节省时间：

SharedPreferences preferences = null;
preferences = act.getSharedPreferences("your_name", Activity.MODE_PRIVATE);
preferences.edit().putString("TIME", getCurrentTimeDate())
.commit();

用这个来获得时间：

private String getCurrentTimeDate() {

    Calendar calendar = new GregorianCalendar();
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

    return formatter.format(calendar.getTime());
}

现在有两种解决方案可以继续：

1. 将计时器设置为服务，它将在后台继续运行并不断更新时间

2. 从SharedReferences检索数据，并在每次需要显示值时计算差异

根据要显示此数据的次数选择该选项

计算活动B中的差异：

    Calendar calendar = new GregorianCalendar();
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

    SharedPreferences shared = getSharedPreferences("your_name", MODE_PRIVATE);
    String saved_time = (shared.getString("TIME", ""));

    Date date = null,date2 = null;
    try {
        date = formatter.parse(saved_time);
    } catch (ParseException e) {
        e.printStackTrace();
    }


    String currentTime = getCurrentTimeDate();
    try {
        date2 = formatter.parse(currentTime);
    } catch (ParseException e) {
        e.printStackTrace();
    }

    printDifference(date,date2);

方法：在此活动中也使用相同的getCurrentTimeDate

public void printDifference(Date startDate, Date endDate){

    //milliseconds
    long different = endDate.getTime() - startDate.getTime();

    System.out.println("startDate : " + startDate);
    System.out.println("endDate : "+ endDate);
    System.out.println("different : " + different);

    long secondsInMilli = 1000;
    long minutesInMilli = secondsInMilli * 60;
    long hoursInMilli = minutesInMilli * 60;
    long daysInMilli = hoursInMilli * 24;

    //long elapsedDays = different / daysInMilli;
    //different = different % daysInMilli;

    long elapsedHours = different / hoursInMilli;
    different = different % hoursInMilli;

    long elapsedMinutes = different / minutesInMilli;
    different = different % minutesInMilli;

    long elapsedSeconds = different / secondsInMilli;

    System.out.printf(
            "%d hours, %d minutes, %d seconds%n",
            elapsedHours, elapsedMinutes, elapsedSeconds);

}