Sum hours and minutes together Java

Summing hours and minutes together results in the wrong answer.

Here are 2 lists with hours.

[[0 hours : 0 mins : 0 sec, 1 hours : 16 mins : 22 sec, 0 hours : 1 mins : 53 sec, 23 hours : 54 mins : 18 sec], [0 hours : 8 mins : 22 sec, 0 hours : 8 mins : 22 sec, 0 hours : 8 mins : 22 sec]]this is HOURS

Then, I divide it into sublists, to calculate for each. Here is one of the sublists.

[0 hours : 0 mins : 0 sec, 1 hours : 16 mins : 22 sec, 0 hours : 1 mins : 53 sec, 23 hours : 54 mins : 18 sec]

So, the answer I get for this sublist is: 1 hours:12 minutes:33 seconds, which is incorrect. I suppose to get around 25 hours plus a few minutes.

public List<String> getTheHoursWorked() {
DateTimeFormatter parser = DateTimeFormatter.ofPattern("H 'hours :' m 'mins :' s 'sec'", Locale.US);
final DateFormat dt = new SimpleDateFormat("HH:mm:ss");
final Calendar c = Calendar.getInstance(TimeZone.getDefault(), Locale.getDefault());
c.clear();
long startingMS = c.getTimeInMillis();
int counter = 0;
for (int k = 0; k < hours.size(); k++){
List<Object> shorter = new ArrayList<>();
List<Object> temp;
temp = (List<Object>) hours.get(k);
long milliseconds = 0;
for (int m = 0; m < shorter.size(); m++) {
LocalTime odt = LocalTime.parse((CharSequence) shorter.get(m), parser);
DateTimeFormatter formatter =
DateTimeFormatter.ofPattern("HH:mm:ss");
String printDate = formatter.format(odt);
try {
milliseconds = milliseconds + (dt.parse(printDate).getTime() - startingMS);
System.out.println(milliseconds + "MILISECONDS");
} catch (ParseException e) {
e.printStackTrace();
}
}
hoursToString.add(String.valueOf(shorter));
String s = milliseconds / 1000 % 60   + " seconds";
String m = milliseconds /(60 * 1000) % 60 + " minutes";
String h = milliseconds / (60 * 60 * 1000) % 24 + " hours";
String together = h+":"+m+":"+s;
togetherHours.add(together);
}
return togetherHours;
}

The steps of the solution should be

1. Start with a time of 0:0
2. Iterate the list and add all hours, minutes and seconds separately after parsing the time strings using the corresponding formatter.
3. Adjust hour, minutes and seconds if minute and/or second exceed 60.

Demo:

import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import java.util.List;
public class Main {
public static void main(String[] args) {
List<String> list = List.of("0 hours : 0 mins : 0 sec", "1 hours : 16 mins : 22 sec",
"0 hours : 1 mins : 53 sec", "23 hours : 54 mins : 18 sec");
// Start with a time of 0:0
int sumHours = 0;
int sumMinutes = 0;
int sumSeconds = 0;
// Iterate the list and add all hours, minutes and seconds separately after
// parsing the time strings using the corresponding formatter
DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern("H' hours : 'm' mins : 's' sec'");
for (String strTime : list) {
LocalTime time = LocalTime.parse(strTime, timeFormatter);
sumHours += time.getHour();
sumMinutes += time.getMinute();
sumSeconds += time.getSecond();
}
// Adjust hour, minutes and seconds if minute and/or second exceed 60
sumMinutes += sumSeconds / 60;
sumSeconds %= 60;
sumHours += sumMinutes / 60;
sumMinutes %= 60;
String strSum = String.format("%d hours : %d mins : %d sec", sumHours, sumMinutes, sumSeconds);
System.out.println(strSum);
}
}

Output:

25 hours : 12 mins : 33 sec

One way to approach this is to use Duration. Convert each time value to a duration and then sum them. The supplied time values are shown in an array of two strings.

String[] hours = {
"0 hours : 0 mins : 0 sec, 1 hours : 16 mins : 22 sec, 0 hours : 1 mins : 53"
+ "sec, 23 hours : 54 mins : 18 sec",
"0 hours : 8 mins : 22 sec, 0 hours : 8"
+ " mins : 22 sec, 0 hours : 8 mins : 22 sec" };

The conversion is done using streams. The process is explained in the comments.

List<Duration> times = Arrays.stream(hours)
// remove all the spaces in each string
.map(str -> str.replaceAll("\\s+", ""))
// split each string on the commas.  At this
// point, each string is processed independently
// of the other in a separate stream
.map(str -> Arrays.stream(str.split(","))
// parse the time
.map(tm -> LocalTime.parse(tm,
DateTimeFormatter.ofPattern(
"H'hours':m'mins':s'sec'")))
// convert each time to a duration
.map(lt -> Duration
.between(LocalTime.of(0, 0, 0), lt))
// sum the durations
.reduce(Duration.ZERO, (a, b) -> a.plus(b)))
// and collect in a list
.collect(Collectors.toList());

At this point you can print the durations in the standard Duration format.

times.forEach(System.out::println);

Prints

PT25H12M33S
PT25M6S

To print them in a more familiar format, the following lambda can be used.

Function<Duration, String> durationToString = d -> {
StringBuilder timeString = new StringBuilder();   
long h = d.toDaysPart()*24+d.toHoursPart();
timeString.append(h == 1 ? (h + " hour ") : h > 1 ?  (h + " hours ") : "");
long m = d.toMinutesPart();
timeString.append(m == 1 ? (m + " minute ") : m > 1 ? (m + " minutes ") : "");
long s = d.toSecondsPart();
timeString.append(s == 1 ? (s + " second ") : s > 1 ? (s + " seconds ") : "");
return timeString.toString();
};

Prints

25 hours 12 minutes 33 seconds 
25 minutes 6 seconds 
</details>
# 答案3
**得分**: 1
1) 你例程中的逻辑错误是 %24，所以你移除了整天。
2) 你的代码包含了许多无用的部分，比如 temp，并且不够清晰。
3) 在循环中构建解析器是一个非常糟糕的风格。
4) 你做了很多不必要的工作，使用毫秒和日历进行操作是没有意义的。这里有两个版本可以返回预期的结果。第二个版本适用于更新的 Java 版本。
```java
public static List<String> getTheHoursWorked() {
final DateTimeFormatter parser = DateTimeFormatter.ofPattern("H 'hours :' m 'mins :' s 'sec'", Locale.US);
final List<String> togetherHours = new LinkedList<>();
for (int k = 0; k < hours.size(); k++){
final List<String> shorter = hours.get(k);
long seconds = 0;
for (int m = 0; m < shorter.size(); m++) {
final LocalTime odt = LocalTime.parse(shorter.get(m), parser);
seconds += odt.getHour() * 3600 + odt.getMinute() * 60 + odt.getSecond();
}
final String s = (seconds       ) % 60 + " seconds";
final String m = (seconds /   60) % 60 + " minutes";
final String h = (seconds / 3600)      + " hours";
final String together = h+":"+m+":"+s;
togetherHours.add(together);
}
return togetherHours;
}
public static List<String> getTheHoursWorked_new() {
final DateTimeFormatter parser = DateTimeFormatter.ofPattern("H 'hours :' m 'mins :' s 'sec'", Locale.US);
final List<String> togetherHours = new LinkedList<>();
for (final var shorter: hours){
long seconds = 0;
for (final var duration : shorter) {
final LocalTime odt = LocalTime.parse(duration, parser);
seconds += odt.getHour() * 3600 + odt.getMinute() * 60 + odt.getSecond();
}
final String s = (seconds       ) % 60 + " seconds";
final String m = (seconds /   60) % 60 + " minutes";
final String h = (seconds / 3600)      + " hours";
final String together = h+":"+m+":"+s;
togetherHours.add(together);
}
return togetherHours;
}