Please make sure you have read the Tag Syntax document and understand how tag attribute syntax works.
Renders an HTML input element of type checkbox, populated by the specified property from the ValueStack.
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/checkbox-description.html %}
{% remote_file_content https://raw.githubusercontent.com/apache/struts/master/core/src/site/resources/tags/checkbox-attributes.html %}
<s:checkbox label="checkbox test" name="checkboxField1" value="aBoolean" fieldValue="true"/>
#tag( Checkbox "label=checkbox test" "name=checkboxField1" "value=aBoolean" )
<input type="checkbox" name="checkboxField1" value="true" checked="checked" />