error when saving vector in java

Question

This class has the function of storing data from an excel file in an array. But it is not doing so. Can anyone tell me why? I’ve asked a gender question before but I can’t edit it.

public class uni {

public static void main (String[] args) throws IOException{

    String[][] mat_Excel = new String[60][20];

    File excel = new File("gestao.xlsx");
    FileInputStream fich = new FileInputStream(excel);

    //através de biblioteca Poi da apache podemos ler o ficheiro excel
    XSSFWorkbook workbook = new XSSFWorkbook(fich);
    //temos acesso à folha de excel
    XSSFSheet sheet = workbook.getSheetAt(0);

    //iteramos as row da folha de excel
    Iterator<Row> rowIt = sheet.iterator();

    int linha=0, coluna=0;

    while(rowIt.hasNext()){
        Row row  = rowIt.next();
        //iteramos células que estão exatamente nesta row
        Iterator<Cell> cellIterator = row.cellIterator();          
        while(cellIterator.hasNext()){
            Cell cell = cellIterator.next();
            mat_Excel[coluna][linha] = cell.toString();
            //System.out.print(cell.toString() + ";");

            linha++;
        }
        coluna++;   
    }

    System.out.println(Arrays.toString(mat_Excel));
    System.out.println(Arrays.deepToString(mat_Excel));

    workbook.close();
    fich.close();

}
}