The need arose at my client recently to add a checkbox to an existing JSP. The checkbox had to be defaulted to checked. Actually I had asked whether the checkbox should be defaulted to checked. This was a proud moment for me. It is not often that I have been presented with such an easy request, with good requirements around it. A checkbox is a single line of HTML code: 

<input type="checkbox" name="vehicle" value="Bike" />

and to default the box to checked it can look something like this:

<input type="checkbox" name="vehicle" value="true" checked="true"/>