如何从 Java 字符串转换为 hh:mm:ss 格式的日期？

Question

1. From one of my web service method call returns Strings which are float values:

   Ex: 375.677, 61.47 etc.

2. These values are nothing but minutes 931 and 500 seconds.
3. But I have to convert this String to Date format of HH:MM:SS which means like this: Ex: 06:20:04.

I have looked into stack exchange questions and tried a solution below. But that is returning the invalid values. Here is the code I tried:

    float f = Float.parseFloat("375.677");

    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.add(Calendar.HOUR_OF_DAY, (int) f);
    calendar.set(Calendar.MINUTE, (int) ((f * 60) % 60));
    calendar.set(Calendar.SECOND, (int) ((f * 3600) % 3600));

    SimpleDateFormat dateFormat = new SimpleDateFormat("hh:mm:ss");
    System.out.println(dateFormat.format(calendar.getTime()));

Please let me know how to resolve this.

Thanks in advance, Saku

Answer 1

Only JDK 1.5 is necessary.

    String input = "375.677";
    int mins = 0;
    int secs = 0;
    StringTokenizer st = new StringTokenizer(input, ".");
    if (st.hasMoreTokens()) mins = Integer.parseInt(st.nextToken());
    if (st.hasMoreTokens()) secs = Integer.parseInt(st.nextToken());
    if (st.hasMoreTokens()) throw new IllegalStateException("Second dot not allowed!");

    int seconds = mins*60+secs;
    int ss = seconds % 60;
    seconds = seconds / 60;
    int mm = seconds % 60;
    seconds = seconds / 60;
    int hh = seconds;

    System.out.println(String.format("%02d:%02d:%02d", hh, mm, ss));

Answer 2

I'm guessing you mean minutes before the point, and seconds after it, where the minutes go up to 931 and seconds go up to 500. If so, try

float f = Float.parseFloat("375.677");
int m = ((int) f);
int s = ((int) (f * 1000)) % 1000;
// handle second overflow
m += s / 60;
s %= 60;
// handle minute overflow
int h = m / 60;
m %= 60;

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.HOUR_OF_DAY, h);
calendar.set(Calendar.MINUTE, m);
calendar.set(Calendar.SECOND, s);

SimpleDateFormat dateFormat = new SimpleDateFormat("hh:mm:ss");
System.out.println(dateFormat.format(calendar.getTime()));

Answer 3

Convert everything to seconds:

    String timeString = "234.34";
    String[] timeValuesAfterSplit = timeString.split("\\.");
    int minutesToSeconds = Integer.parseInt(timeValuesAfterSplit[0]) * 60;
    int totalSeconds = minutesToSeconds + Integer.parseInt(timeValuesAfterSplit[1]);

Now get the time in the given format using LocalTime as:

LocalTime localTime = LocalTime.ofSecondOfDay(totalSeconds);

And then the format that you need could be obtained by calling toString() on localTime .