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javarowopencsv

OpenCSV Get Value from last row and specific column


I am trying to get the values from the second last row and third column in a semicolon separated file. I can't seat to get the values from the second last row and the third column.

I have searched for a method to achieve this but it has been fruitless. I would greatly appreciate if someone could point me in the right direction with an example.

This is the code I have so far:

private static void readmyfile() throws IOException {

    String csvFilename = "C:/test.csv";

    CSVReader reader = new CSVReader(new FileReader(csvFilename), ';', '\'', 1);
    String[] nextLine;

    int rowNumber=-1;

    nextLine=reader.readNext();
    while (nextLine!=null){
        rowNumber++;
        String speed = nextLine[rowNumber];
        System.out.println(speed);
        nextLine=reader.readNext();
    }
}

My file is formatted like this:

Number; ID; NUM; Counter; Time
1;CCF;9999;1;18:07:05
1;CC8;8888;1;18:07:15
1;CC1;8888;1;18:07:15
1;DC7;1111;1;18:07:15
Date:;01/01/2000; Read:;5; on:;01.05; off:;02.04

Solution

  • Although you are reading the 2nd last line, this could possibly change to the 3rd or 4th last lines. Doing a custom solution here would definitely prove brittle. Therefore using a circular buffer such as Apache's CircularFifoBuffer will allow lines to be added without having to maintain a position count:

    CSVReader reader = new CSVReader(new FileReader(csvFilename), ';', '\'', 1);
    
    int rowCount = 2;                                    // save last 2 lines
    Buffer<String[]> savedBuffer = new CircularFifoBuffer<String[]>(rowCount); 
    String[] nextLine;
    while ((nextLine = reader.readNext()) != null) {
       savedBuffer.add(nextLine);
    }
    
    int columnIndex = 2; // zero based
    System.out.println(savedBuffer.get()[columnIndex]);
    

    Note: You will need the Generics version of Commons-Collections for this example.