Returning a specifc part of each line in a txtfile and storing it into a double

Question

I want to return the part of each line that contains a dot between the numbers which is the GPA portion of each line from a text file.

I can figure out how to read each line in the text file and print it. I have tried using .contains and .substring to try to capture the portion I want from each line but I do not know how to do so.

1.wita7557 | william | tang | male | 3.0 | counselor | 5 | database | leader  
2.tosm5791 | tommy | smith | male | 3.5 | mastermind | 5 | designer | leader  
3.drco5905 | drew | collins | male | 3.7 | inspector | 3 | designer | programmer

so from the above code I would want an expected result into an array such as [3.0,3.5,3.7]

Split your line at each `|` using `line.split("\\|")` and get your desierd string at the 4th index of the resulting array. — Eritrean, Nov 08 '19 at 11:01
You need to google 3 things: How to read a file line by line? How to split a string on pipe character? How to trim a String? — Bentaye, Nov 08 '19 at 12:38

score 0 · Answer 1 · answered Nov 08 '19 at 11:06

0

the below should give you the 5th element from each line (split by '|' ) :

line.split("\\|")[4]

answered Nov 08 '19 at 11:06

nullPointer

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score 0 · Answer 2 · answered Nov 08 '19 at 11:22

0

Example code

Double.valueOf(
"2.tosm5791 | tommy | smith | male | 3.5 | mastermind | 5 | designer | leader"
.split("\\|")[4])

answered Nov 08 '19 at 11:22

lczapski

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score 0 · Answer 3 · answered Nov 08 '19 at 12:27

Complete program:

public static void main(String[] args) {
    try {
        BufferedReader reader = new BufferedReader(new FileReader("C:/Users/user/Desktop/input.txt"));
        List<Double> doubleList = new ArrayList<>();
        String buff[];
        String line = reader.readLine();
        while (line != null) {
            buff = line.split("\\|");           
            doubleList.add(Double.parseDouble(buff[4]));
            line = reader.readLine();
        }
        reader.close();
        System.out.println(doubleList);
    } catch (IOException e) {
        e.printStackTrace();
    }

}

Bentaye · Answer 4 · 2019-11-08T13:58:31.393

What you want to do is:

Read a file line by line
Split each line on the | character into an array
take the 5th element of the array
Parse it into a double
make a list out of all of them

This can be done using a single lambda this way:

List<Double> list = Files.lines(Paths.get("myFile.txt")) // real all lines
    .map(line -> line.split("\\|"))                      // split each line on the | character
    .map(array -> array[4])                              // take the 5th element (index 4)
    .mapToDouble(Double::valueOf)                        // parse them into doubles
    .boxed()                                             // box them to allow collection
    .collect(Collectors.toList());                       // make a list out of them

Or same thing without lambdas:

List<String> lines = Files.readAllLines(Paths.get("myFile.txt"));
List<Double> list = new ArrayList<>();
String[] array;
String stringValue;
Double doubleValue;
for(String line : lines) {
    array = line.split("\\|");
    stringValue = array[4];
    doubleValue = Double.valueOf(stringValue);
    list.add(doubleValue);
}

Note: Files.line() throws an IOException so you will need to write that code into a try/catch/finally block

Returning a specifc part of each line in a txtfile and storing it into a double

4 Answers4