title: How to erase rows in a table if an expression is valid in iReport
body: <p>I have a table in iReport with 3 fields (A, B, C). I would to print the row iff field C is not null. For example if I have 2 records in my data source:</p>
  
  <ol>
  <li><p>A = first, B = second, C = third</p></li>
  <li><p>A = up, B = down, C = NULL</p></li>
  </ol>
  
  <p>the table must have only the first row.</p>
  
  <p>I have tried inserting this expression in each cell (in "Print when expression" property):</p>
  
  <pre><code>!$F{C}.equals(null)
  </code></pre>
  
  <p>but in this way the result is that the second row is empty (but visible).</p>
  
  <p>Edit: after the first answer (now erased) the columns in the table are something like:</p>
  
  <pre><code>&lt;jr:column ...&gt;
  &lt;jr:columnHeader ...&gt;
     &lt;staticText&gt;
      &lt;reportElement .../&gt;
          &lt;text&gt;&lt;![CDATA[ID]]&gt;&lt;/text&gt;
     &lt;/staticText&gt;
  &lt;/jr:columnHeader&gt;
  &lt;jr:detailCell ...&gt;
     &lt;textField isBlankWhenNull="false"&gt;
      &lt;reportElement ... isRemoveLineWhenBlank="true"&gt;
          &lt;printWhenExpression&gt;&lt;![CDATA[$F{ID}!=null]]&gt;&lt;/printWhenExpression&gt;
      &lt;/reportElement&gt;
          &lt;textFieldExpression&gt;&lt;![CDATA[$F{ID}]]&gt;&lt;/textFieldExpression&gt;
     &lt;/textField&gt;
  &lt;/jr:detailCell&gt;
  &lt;/jr:column&gt;
  &lt;jr:column ...&gt;
  &lt;jr:columnHeader ...&gt;
      &lt;staticText&gt;
          &lt;reportElement .../&gt;
          &lt;text&gt;&lt;![CDATA[CITY]]&gt;&lt;/text&gt;
      &lt;/staticText&gt;
  &lt;/jr:columnHeader&gt;
  &lt;jr:detailCell ...&gt;
      &lt;textField isBlankWhenNull="false"&gt;
          &lt;reportElement ... isRemoveLineWhenBlank="true"&gt;
              &lt;printWhenExpression&gt;&lt;![CDATA[$F{ID}!=null]]&gt;&lt;/printWhenExpression&gt;
          &lt;/reportElement&gt;
          &lt;textFieldExpression&gt;&lt;![CDATA[$F{CITY}]]&gt;&lt;/textFieldExpression&gt;
      &lt;/textField&gt;
  &lt;/jr:detailCell&gt;
  &lt;/jr:column&gt;
  </code></pre>
  
  <p>The data source is a xml file. I've tried also with <code>isBlankWhenNull="true"</code> but with no change. Here a screen of the result:
  <img src="https://i.stack.imgur.com/Mu8H1.png" alt="tab"></p>