For my project, I have to read in data that is given to us in a CSV file and write it out in a certain format. I have it almost done but the problem I am having is that my program is not completely reading through the times that are given. From here my program is just reading all the times that I am given.
I’ve tried to convert String time to an Integer but it gives me an InputMismatchException.
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class MusicInventory {
public long toHoursPart(Duration d) {
return d.toHours() / 3600;
}
public long toMinutesPart(Duration d) {
return d.toMinutes() % 60;
}
public long toSecondsPart(Duration d) {
return d.toMillis() / 1000 % 60;
}
public static void process(File input, File output) throws FileNotFoundException {
//read file
List<String> inList = new ArrayList<>();
try(Scanner scan = new Scanner(input)) {
while(scan.hasNext()){
String line = scan.nextLine();
inList.add(line);
}
}
//process data
List<String> outList = new ArrayList<>();
for (String now : inList) {
try (Scanner scan = new Scanner(now)){
scan.useDelimiter(",");
String name = scan.next();
String album = scan.next();
String time = scan.nextLine();
String next = String.format("%s | %s | %s ", name, album, time);
outList.add(next);
}
}
//write file
try (PrintWriter pw = new PrintWriter(output)){
for (String s : outList) {
pw.println(s);
}
}
}
}
This should return
[Sesame Street | Best of Elmo | 0:28:11]
but it returns
[Best of Elmo | Sesame Street | ,2:29,1:30,2:09,1:46,1:55,2:02,1:42,2:40,1:56,1:30,2:03,1:14,2:28,2:47]
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Answer
You may consider finding and using a third-party library for reading your CSV file. There are some, also some that you can use for free.
I assume that a line in your CSV file looks like this:
Best of Elmo,Sesame Street,2:29,1:30,2:09,1:46,1:55,2:02,1:42,2:40,1:56,1:30,2:03,1:14,2:28,2:47
That is, no quotes in the line and no commas within the name or album title. In this case it should be manageable to read and parse the file using Scanner the way you are trying. For scanning the times use an inner loop, Scanner.hasNext() and Scanner.next() (not Scanner.nextLine()). Parse each time from Scanner.next() into a Duration. It’s not completely trivial, but there are already answers explaining how to do that. I insert a link at the bottom. Use Duration.plus(Duration) for summing up the durations. Finally you need to format the total duration back into a string for output. I include another link for that.