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Java

Lukas Baumgartner
Lukas Baumgartner
14,817 Points
Posted by Lukas Baumgartner
Lukas Baumgartner
14,817 Points

Java 8 Streams

Hey, Right now I'm stuck on a pretty specific problem concerning the java.nio API.

I have a class Data with the constructor 

public Data(String name, String firstName, String stdtId, String skz, List<Integer> submitted, List<Double> points, double test)

and a .csv file that contains values like:

1;NAME;FIRSTNAME;1234567;521; 1;1;0;1;1;1;1;1;1;1;0;  19;23;22;21;;16;17;18;19;20;21;9

per line. and the values: [1;1;0;1;1;1;1;1;1;1;0;] and: [19;23;22;21;;16;17;18;19;20;21;9] should be put in Lists (because of the constructor for the Data object)

I want to use a Stream to read the file, but I do not know how to make Lists inside a Stream?

My class looks like this so far:

         final String path = "data.csv";
         final int NAME = 1;
         final int FIRSTNAME = 2;
         final int STDID = 3;
         final int SKZ = 4;
         final int SUBMITTED = 5;  //most probably wrong the list should be 11 items long
         final int POINTS = 6; //most probably wrong the list should be 11 items long
         final int TEST = 7;



        List<Data> list =
                Files.lines(Paths.get(path))
                        .skip(1)        //skip line 1
                        .map(line -> line.split(";"))                   //split each line at ; and make it to an array
                        .map(elem -> new Data(  elem[NAME],
                                                elem[FIRSTNAME],
                                                elem[STDID],
                                                elem[SKZ],
                                                //TODO: add SUBMITTED List,
                                                //TODO: add POINTS List,
                                                Double.parseDouble(elem[TEST])) //make each line a data object
                        .collect(Collectors.toList()));

        for(Data d:list){
            System.out.println(d);
        }
Lukas Baumgartner
Lukas Baumgartner
14,817 Points
Lukas Baumgartner
Lukas Baumgartner
14,817 Points

If anyone is interested, I solved it:

        List<Data> dataList =
                Files.lines(Paths.get(path))
                        .skip(1)        //skip line 1
                        .map(line -> line.split(";",-1))                   //split each line at ; and make it to an array
                        .map(elem -> new Data(  elem[NAME],
                                                elem[FIRSTNAME],
                                                elem[STDID],
                                                elem[SKZ],
                                                Arrays.stream(Arrays.copyOfRange(elem, 5, 15))
                                                        .map(String::trim)
                                                        .mapToInt(Integer::parseInt)
                                                        .boxed()
                                                        .collect(Collectors.toList()),
                                                Arrays.stream(Arrays.copyOfRange(elem, 16, 26))
                                                        .map(itm -> (itm.isEmpty() ? "0" : itm))
                                                        .map(String::trim)
                                                        .mapToDouble(Double::parseDouble)
                                                        .boxed()
                                                        .collect(Collectors.toList()),
                                                elem[TEST].isEmpty() ? 0 : Double.parseDouble(elem[TEST]))) //make each line a data object
                        .sorted(Comparator.comparing(Data::toString))
                        .collect(Collectors.toList());