a new field with no metadata.

 <pre><code>
 StructType schema = new StructType()
     .add("a", new IntegerType(), true)
     .add("b", new LongType(), false)
     .add("c", new StringType(), true)
 </code></pre></div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>fieldName</code> - The name of the new field.</dd>
<dd><code>dataType</code> - The datatype for the new field.</dd>
<dd><code>nullable</code> - Whether or not the new field is nullable.</dd>
<dt><span class="returnLabel">Ret