How to extract data from Excel sheet using Apache POI in java(lookup framing)

public class Array_Learn {
    public static void main(String[] args) {
        try {
            FileInputStream ExcelFile = new FileInputStream(new File("C:\\Users\\Anbu.B\\Desktop\\POI-Test\\mediTask.xlsx"));
            XSSFWorkbook book1 = new XSSFWorkbook(ExcelFile);
            XSSFSheet sheet = book1.getSheetAt(0);
            Iterator<Row> rowiter = sheet.iterator();
            while (rowiter.hasNext()) {
                XSSFRow row = (XSSFRow) rowiter.next();
                if (row.getRowNum() == 2) {
                    Iterator cellIterator = row.cellIterator();
                    while (cellIterator.hasNext()) {
                        XSSFCell cell = (XSSFCell) cellIterator.next();
                        if (cell.getStringCellValue().contains("|")) {
                            String split[] = cell.getStringCellValue().split("\\|");
                        }
                    }
                }
            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

I need this output:

chest&&pain=J90
lung&&pneumonia=J54.9
lungs&&pneumonia=J54.9
bronchi&&pneumonia=J54.9
bronchus&&pneumonia=J54.9
colon&&ascending&tumor=D12.5
colon&&ascending&carcinoma=D12.5
colon&&ascending&cancer=D12.5
colon&&ascending&&tumor&&resection=D12.6
colon&&descending&&tumor&&resection=D12.6
colon&&ascending&&carcinoma&&resection=D12.6
colon&&descending&&carcinoma&&resection=D12.6
colon&&ascending&&cancer&&resection=D12.6
colon&&descending&&cancer&&resection=D12.6

The above code is doing read row and iterate each cell and check cell contains | symbol condition is true the split statement is working but, I need the above exact output. What I did in the above code:

1. Read the excel file.
2. Read sheet from the excel file.
3. then create row iterator.
4. create cell iterator.
5. check cell contains | symbol then split that cell strings and store into the string array.

You almost finished your task. The key here to use one of the algorithms to generate combinations. You could find a general description of such algorithms there, or more close examples with strings on java there.

Full code example (recursive algorithm):

The ParsedRow class for calculating of different combinations:

class ParsedRow {
    private final List<List<String>> combinations;
    private final String suffix;

    public ParsedRow(List<List<String>> combinations, String suffix) {
        this.combinations = combinations;
        this.suffix = suffix;
    }

    public List<String> combine() {
        List<String> res = new ArrayList<>();
        combine(res, 0, "");
        return res;
    }


    public void combine(List<String> res, int depth, String current) {
        if (combinations.size() == depth) {
            res.add(current + "=" + suffix);
            return;
        }
        String delimiter = current.isEmpty() ? "" : "&&";
        for (int i = 0; i < combinations.get(depth).size(); i++) {
            combine(res, depth + 1, current + delimiter + combinations.get(depth).get(i));
        }
    }
}

The Main class for reading the xlsx file and printing results

public class Main {
    public static void main(String[] args) throws IOException {
        try (final FileInputStream file = new FileInputStream("diseases.xlsx");
             XSSFWorkbook workbook = new XSSFWorkbook(file)) {
            List<String> finalResult = new ArrayList<>();
            for (Row row : workbook.getSheetAt(0)) {
                List<List<String>> combinations = new ArrayList<>();
                String suffix = "";
                for (Cell cell : row) {
                    if (cell.getColumnIndex() != 4) {
                        final List<String> strings = Arrays.asList(cell.getStringCellValue().split("\\|"));
                        combinations.add(strings);
                    } else {
                        suffix = cell.getStringCellValue();
                    }
                }
                ParsedRow parsedRow = new ParsedRow(combinations, suffix);
                finalResult.addAll(parsedRow.combine());
            }
            for (String line : finalResult) {
                System.out.println(line);
            }
        }
    }
}