[java] How to check if an excel cell is empty using Apache POI?

First to avoid NullPointerException you have to add this

Row.MissingCellPolicy.CREATE_NULL_AS_BLANK

This will create a blank cell instead of giving you NPE then you can check to make sure nothing went wrong just like what @Gagravarr have said.

Cell cell = row.getCell(j, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK);
    if (cell == null || cell.getCellTypeEnum() == CellType.BLANK) 
        // do what you want