Cannot invoke excel in eclipse

Question

ERROR:  Cannot invoke "org.apache.poi.xssf.usermodel.XSSFSheet.iterator()" because "utilities.ExcelUtility.ExcelWSheet" is null
    at utilities.ExcelUtility.findCells(ExcelUtility.java:70)

The code:

package utilities;

public class ExcelUtility {

    private static XSSFWorkbook ExcelWBook;
    private static XSSFSheet ExcelWSheet;

    /*
     * Set the File path, open Excel file
     * @params - Excel Path and Sheet Name
     */
    public static void setExcelFile(String path, String sheetName) throws Exception {
        try {
            // Open the Excel file
            FileInputStream ExcelFile = new FileInputStream(path);

            // Access the excel data sheet
            ExcelWBook = new XSSFWorkbook(ExcelFile);
            ExcelWSheet = ExcelWBook.getSheet(sheetName);
        } catch (Exception e) {
            throw (e);
        }
    }

    public static String[][] getTestData(String tableName) {
        String[][] testData = null;

        try {
            // Handle numbers and strings
            DataFormatter formatter = new DataFormatter();
            XSSFCell[] boundaryCells = findCells(tableName);
            XSSFCell startCell = boundaryCells[0];
            
            XSSFCell endCell = boundaryCells[1];
            
            int startRow = startCell.getRowIndex() + 1;
            int endRow = endCell.getRowIndex() - 1;
            int startCol = startCell.getColumnIndex() + 1;
            int endCol = endCell.getColumnIndex() - 1;

            testData = new String[endRow - startRow + 1][endCol - startCol + 1];

            for (int i=startRow+1; i<endRow; i++) {
                for (int j=startCol+1; j<endCol; j++) {
                    // testData[i-startRow][j-startCol] = ExcelWSheet.getRow(i).getCell(j).getStringCellValue();
                    Cell cell = ExcelWSheet.getRow(i).getCell(j);
                    testData[i - startRow][j - startCol] = formatter.formatCellValue(cell);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return testData;
    }

    public static XSSFCell[] findCells(String tableName) {
        DataFormatter formatter = new DataFormatter();
        String pos = "begin";
        XSSFCell[] cells = new XSSFCell[2];

        for (Row row : ExcelWSheet) {
            for (Cell cell : row) {
                // if (tableName.equals(cell.getStringCellValue())) {
                if (tableName.equals(formatter.formatCellValue(cell))) {
                    if (pos.equalsIgnoreCase("begin")) {
                        cells[0] = (XSSFCell) cell;
                        pos = "end";
                    } else {
                        cells[1] = (XSSFCell) cell;
                    }
                }
            }
        }
        return cells;
    }
}

I wanted to use the variables to test username a password from my excel file but seems I cant even open it. I checked the file is in the correct path and the code but I cant seem to find the issue please help