Java: How to convert a string (HH:MM:SS) to a dura

问题:

i want to convert a string with a format of HH:MM:SS or MM:SS or SS into a datatype of Duration.

solution:

    private ArrayList<Duration> myCdDuration = new ArrayList<Duration>();

        private void convert(String aDuration) {

            chooseNewDuration(stringToInt(splitDuration(aDuration))); //stringToInt() returns an int[] and splitDuration() returns a String[]
        }

        private void chooseNewDuration(int[] array) {
            int elements = array.length;
            switch (elements) {
            case 1:
                myCdDuration.add(newDuration(true, 0, 0, 0, 0, 0, array[0]));
                break;
            case 2:
                myCdDuration.add(newDuration(true, 0, 0, 0, 0, array[0], array[1]));
                break;
            case 3:
                myCdDuration.add(newDuration(true, 0, 0, 0, array[0], array[1],
                        array[2]));
                break;
            }
        }

thanks for help ... any easier way to do that ? -> create your own Duration class:

public class Duration {
        private int intSongDuration;
        private String printSongDuration;

        public String getPrintSongDuration() {
            return printSongDuration;
        }

        public void setPrintSongDuration(int songDuration) {
            printSongDuration = intToStringDuration(songDuration);
        }

        public int getIntSongDuration() {
            return intSongDuration;
        }

        public void setIntSongDuration(int songDuration) {
            intSongDuration = songDuration;
        }

        public Duration(int songDuration) {

            setIntSongDuration(songDuration);
        }

Converts the int value into a String for output/print:

private String intToStringDuration(int aDuration) {
    String result = "";

    int hours = 0, minutes = 0, seconds = 0;

    hours = aDuration / 3600;
    minutes = (aDuration - hours * 3600) / 60;
    seconds = (aDuration - (hours * 3600 + minutes * 60));

    result = String.format("%02d:%02d:%02d", hours, minutes, seconds);
    return result;
}

回答1:

1. Your myCdDuration is confusing. Do you want one Duration object equivalent to whatever was specified in the string, or a list of Duration objects where the first contains the hours, the second minutes etc?

2. You can't just cast a String into some other object. You should parse the value into an numeric type and use DataTypeFactory to construct the Duration object.

回答2:

I assume what you're ultimately trying to achieve is to compute the duration of the CD in seconds.

There are several ways to do this, but I think the most straightforward is to just split on : to get the hours, minutes, and seconds fields, then to compute the duration manually:

String timestampStr = "14:35:06";
String[] tokens = timestampStr.split(":");
int hours = Integer.parseInt(tokens[0]);
int minutes = Integer.parseInt(tokens[1]);
int seconds = Integer.parseInt(tokens[2]);
int duration = 3600 * hours + 60 * minutes + seconds;

回答3:

tl;dr

No need to define your own Duration class, as Java provides one.

Duration.between (                  // Represent a span of time of hours, minutes, seconds. 
    LocalTime.MIN ,                 // 00:00:00
    LocalTime.parse ( "08:30:00" )  // Parse text as a time-of-day. 
)                                   // Returns a `Duration` object, a span-of-time. 
.toString()                         // Generate a `String` with text in standard ISO 8601 format. 

PT8H30M

And parse standard ISO 8601 formatted text.

Duration.parse( "PT8H30M" )   // Parse standard ISO 8601 text yo get a `Duration` object. 

Avoid HH:MM:SS format

If by the string 08:30:00 you mean "eight and a half hours" span of time rather than a time-of-day “half-past eight in the morning”, then avoid that format of HH:MM:SS. That format ambiguous, appearing to be a time-of-day. Instead use the standard ISO 8601 format discussed below.

Duration and time-of-day are two very different concepts. You must be clear on them, each should be distinct in your mind. Using the ambiguous format of HH:MM:SS makes that distinction all the more difficult (so avoid that format!).

java.time

The modern way is with the java.time classes.

LocalTime

First parse your string as a LocalTime. This class represents a time-of-day without a date and without a time zone. Having no time zone means these objects are based on a generic 24-hour clock without regard for anomalies such as Daylight Saving Time (DST).

We do not really want a LocalTime as your input string represents a span of time rather than a time-of-day. But this is just the first step.

LocalTime lt = LocalTime.parse ( "08:30:00" );

Duration

To represent the desired span-of-time, we want the Duration class. This class is for spans of time not attached to the timeline. We can create one by converting that LocalTime via getting the amount of time from the beginning of the time-of-day clock, 00:00:00.0 or LocalTime.MIN, and the lt we just instantiated.

Duration d = Duration.between ( LocalTime.MIN , lt );

Editing the input string

The approach above using LocalTime only works if your input strings represent a duration of less than 24 hours. If over 24 hours, you will parse the input string yourself.

Something like the following code. Of course the actual parsing depends on resolving the ambiguity of your particular input string. Is 50:00 meant to be fifty hours or fifty minutes? (This ambiguity is a strong reason to avoid this confusing format whenever possible, and stick with ISO 8601 formats.)

String input = "50:00";  // Or "50:00:00" (fifty hours, either way)

String[] parts = input.split ( ":" );
Duration d = Duration.ZERO;
if ( parts.length == 3 ) {
    int hours = Integer.parseInt ( parts[ 0 ] );
    int minutes = Integer.parseInt ( parts[ 1 ] );
    int seconds = Integer.parseInt ( parts[ 2 ] );
    d = d.plusHours ( hours ).plusMinutes ( minutes ).plusSeconds ( seconds );
} else if ( parts.length == 2 ) {
    int hours = Integer.parseInt ( parts[ 0 ] );
    int minutes = Integer.parseInt ( parts[ 1 ] );
    d = d.plusHours ( hours ).plusMinutes ( minutes );
} else {
    System.out.println ( "ERROR - Unexpected input." );
}

ISO 8601

We can see the result by generating a String in standard ISO 8601 format for durations by simply calling Duration::toString. The java.time classes use ISO 8601 by default when parsing/generating strings. For durations, the standard format is PnYnMnDTnHnMnS where the P marks the beginning and the T separates the years-months-days portion from the hours-minutes-seconds portion. So, our eight-and-a-half hours will appear as PT8H30M.

System.out.println ( "d.toString(): " + d );

d.toString(): PT8H30M

Collecting Duration objects

You can make a List holding elements of the type Duration.

List<Duration> durations = new ArrayList<>( 3 );  // Initial capacity of 3 elements.
durations.add( d ) ;
durations.add( Duration.between ( LocalTime.MIN , LocalTime.parse ( "03:00:00" ) ) ) ;
durations.add( Duration.between ( LocalTime.MIN , LocalTime.parse ( "01:15:00" ) ) ) ;

durations.toString(): [PT8H30M, PT3H, PT1H15M]

Remember that the strings you see in that output like PT8H30M are just that: output of generated strings. The Duration type is not a simple string but rather generates a String object by its toString method.

If you stick to the ISO 8601 formats, you can easily parse as well as generate such strings. No need to go through the LocalTime conversion rigamarole we performed at the top of this Answer.

Duration d = Duration.parse( "PT8H30M" );

See this example code live in IdeOne.com.

---

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8 and SE 9 and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

回答4:

I have written this method in my utils class to parse various kind of duration strings. It is quite flexible :

public static int getSecondsFromFormattedDuration(String duration){
        if(duration==null)
            return 0;
        try{

            Pattern patternDuration = Pattern.compile("\\d+(?::\\d+){0,2}");

            int hours = 0;
            int minutes = 0;
            int seconds = 0;
            if(patternDuration.matcher(duration).matches()){
                String[] tokens = duration.split(":");
                if(tokens.length==1){
                    seconds = Integer.parseInt(tokens[0]);
                }else if(tokens.length == 2){
                    minutes = Integer.parseInt(tokens[0]);
                    seconds = Integer.parseInt(tokens[1]);
                }else{
                    hours = Integer.parseInt(tokens[0]);
                    minutes = Integer.parseInt(tokens[1]);
                    seconds = Integer.parseInt(tokens[2]);
                }

                return 3600 * hours + 60 * minutes + seconds;
            }else
                return 0;

        }catch (NumberFormatException ignored){
            return 0;
        }

}

This is how it parsed these durations :

"1"   -->  1
"10"  -->  10
"10:"   -->  0  (not a valid duration)
"10:07"   -->  607
"06:08"   -->  368
"7:22"   -->  442
":22"   -->  0  (not a valid duration)
"10:32:33"   -->  37953
"2:33:22"   -->  9202
"2:2:02"   -->  7322
"2:33:43:32"   -->  0  (not a valid duration)
"33ff"   -->  0  (not a valid duration)
"2d:33"   -->  0  (not a valid duration)

回答5:

I would suggest not using javax.xml.datatype.Duration, as its related to the XML Java API and it's confusing to use it if you are not dealing with XML. Moreover, it is an abstract class, and there's no non-abstract documented implementation of it in Java SE, so you'd have to either create your own non-abstract implementation or obtain an instance somehow (probably, playing with the XML API).

You manage time and dates in Java using the Date and Calendar classes. To convert Strings to Date/Calendar you use DateFormat or SimpleDateFormat. That will let you perform your duration arithmetic, although that's not 100% pretty.

Mansoor provides a way to do stuff manually using String manipulation and handling durations as numeric values- if you only do simple stuff, it might be more straightforward to do that.

If you have to perform more complex stuff, you might want to look into http://joda-time.sourceforge.net/

回答6:

With Java 8 and Java.time.Duration you can do this given that the string is of the format HH:MM:SS or MM:SS or SS

Duration.ofSeconds(Arrays.stream(runtime.split(":"))
                  .mapToInt(n -> Integer.parseInt(n))
                  .reduce(0, (n, m) -> n * 60 + m));

回答7:

Sample, Convert Current DateTime to Duration in Java 7.

DatatypeFactory.newInstance().newDuration(Calendar.getInstance().getTimeInMillis())

Output -

P48Y5M13DT19H59M24.658S