title: Issue with reading blank cells in large xlsx files using apache POI/monitorjbl/excel-streaming-reader
body: <p>I am working on requirement where I need to read large xlsx file contains more than one million records. The apache POI is not memory efficient when reading large files .Hence I am using below API which adds </p>
  
  <p><a href="https://github.com/monitorjbl/excel-streaming-reader" rel="nofollow">https://github.com/monitorjbl/excel-streaming-reader</a> which is a wrapper around that streaming API while preserving the syntax of the standard POI API. Everything working fine except reading blank cells in the row. The above API throwing null pointer if cell is blank</p>
  
  <pre><code>       for(int i=0; i&lt;=expectedColumns-1; i++) {
                Cell cell = row.getCell(i);
      switch (cell.getCellType()) {
      }
              }
  java.lang.NullPointerException
  at test.XLSXToCSVConverterStreamer.xlsx(XLSXToCSVConverterStreamer.java:67)
  at test.XLSXToCSVConverterStreamer.main(XLSXToCSVConverterStreamer.java:164)
  </code></pre>
  
  <p>if  a cell in row is null it is throwing null pointer at Switch case i.e cell.getCelltype. I have modified code to read null cells as blank cells but its not supporting</p>
  
  <pre><code>    for(int i=0; i&lt;=expectedColumns-1; i++) {
        //Cell cell = row.getCell(i);
       Cell cell = row.getCell(i, Row.CREATE_NULL_AS_BLANK);
  switch (cell.getCellType()) {
  }
      }
  </code></pre>
  
  <p>if I use Cell cell = row.getCell(i, Row.CREATE_NULL_AS_BLANK) to read empty cells as blank I am getting below issue. Kindly help me in resolving this</p>
  
  <pre><code>com.monitorjbl.xlsx.exceptions.NotSupportedException
  at com.monitorjbl.xlsx.impl.StreamingRow.getCell(StreamingRow.java:108)
  </code></pre>