使用Apache POI加载xlsx文件时发生NullpointerException

Question

Am tryng to read a file using Apache POI 3.8 in mac osx environment, which is created in Windows using Open XML SDK 2.0 for Microsoft Office, am getting null pointer exception as it is unable to load the xlsx file. Below is the stack trace. I am able to open the file and view it.

The same code works for the files that I create in mac os env. If i open and save the file before processing, am not having any issue. Note : The File size increases after saving it. Is it issue with file being generated in .net and being processed in mac osx environment.

Any clues why am i getting below error.

Caused by: java.lang.NullPointerException
        at org.apache.poi.xssf.usermodel.XSSFWorkbook.onDocumentRead(XSSFWorkbook.java:253)
        at org.apache.poi.POIXMLDocument.load(POIXMLDocument.java:159)
        at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:183)
        at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:73) 

The class looks like below, with utility methods, did not copy the entire class. but this happens at line wb = new XSSFWorkbook(bis) while creating the workbook. I tried couple of options like WorkbookFactory.create(bis) instead of XSSFWorkbook , but the error remains same, issue is mainly with the file content.

public class XLSXReader {

    private BufferedInputStream bis;
    private boolean hasNext = true;
    int skipLines;

    private boolean linesSkiped;

    //   The default line to start reading.
    public static final int DEFAULT_SKIP_LINES = 0;

    private XSSFWorkbook wb =null;
    private XSSFSheet sheet=null;
    private int noOfCols;

    public XLSXReader(InputStream is){
        bis = new BufferedInputStream(is);
        this.noOfCols=0; 
        try {
            wb = new XSSFWorkbook(bis); 
            sheet = wb.getSheetAt(0);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

// with basic utility methods ....
}

Answer 1

I think, your missing the class path problem. Try as below. Make sure that properties directry must be in the class path . Put your doucments file in these folder.

public class WorkBookReader {
    public static void main(String[] args) {
        try {
            InputStream inp = new FileInputStream("properties/workbook.xls");
            Workbook wb = WorkbookFactory.create(inp);
            Sheet sheet = wb.getSheetAt(0);
            Row row = sheet.getRow(2);
            Cell cell = row.getCell(3);
            if (cell == null)
                cell = row.createCell(5);
            cell.setCellType(Cell.CELL_TYPE_STRING);
            cell.setCellValue("Hello!");

            // Write the output to a file
            FileOutputStream fileOut = new FileOutputStream("properties/workbook.xls");
            wb.write(fileOut);
            fileOut.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InvalidFormatException e) {
            e.printStackTrace();
        }
    }
}