how to use multiple checkboxes in jsp

i am working on my academic project which is in jsp servlet. here i want to use multiple checkboxes in which one checkbox is root. on clicking that root checkbox, childrens should get expanded. However i did that but when i open page sub sub checkboxes i.e childrens expanded automatically. i want these children's in collapsed format when page opens.

this is my script
<script type="text/javascript" language="JavaScript">
function HidePart(d) { document.getElementById(d).style.display = "none";  }
function ShowPart(d) { document.getElementById(d).style.display = "block"; }
function CheckboxChecked(b,d)
{
   if(b) { ShowPart(d); }
else  { HidePart(d); }

}