title: Apache POI Streamsheet getRow unsupported operation exception
body: <p>I want to read more than 600k rows from an excel (.xlsx) file.</p>
  
  <p>I'm using Apache POI and xlsx-streamer.</p>
  
  <pre><code>&lt;dependency&gt;
          &lt;groupId&gt;com.monitorjbl&lt;/groupId&gt;
          &lt;artifactId&gt;xlsx-streamer&lt;/artifactId&gt;
          &lt;version&gt;1.2.0&lt;/version&gt;
  &lt;/dependency&gt;
  </code></pre>
  
  <p>Apache poi version is 3.15 because xlsx-streamer didn't support in above versions</p>
  
  <p>I want to iterate only particular columns. What I have tried is:</p>
  
  <pre><code>File myFile = new File("testFile.xlsx");
  
      FileInputStream fis = new FileInputStream(myFile);
      Workbook workbook = StreamingReader.builder().bufferSize(4096).open(fis);
      // Sheet sheet = workbook.getSheetAt(0);
      for (Sheet sheet : workbook) {
          for (int r = 0; r &lt; sheet.getLastRowNum(); r++) {
              Row rr = sheet.getRow(r);
              for (int c = 1; c &lt; rr.getLastCellNum(); c++) {
                  Cell cell = rr.getCell(c);
                  System.out.println("" + cell.getStringCellValue());
              }
          }
  </code></pre>
  
  <p>I get this exception with few warnings</p>
  
  <pre><code>Exception in thread "main" java.lang.UnsupportedOperationException
  at com.monitorjbl.xlsx.impl.StreamingSheet.getRow(StreamingSheet.java:102)
  at ReadExcel.main(ReadExcel.java:35)
  </code></pre>
  
  <p>Line #35 is</p>
  
  <pre><code>Row rr = sheet.getRow(r);
  </code></pre>