Java Sax xml - Trace child tag name from Parent tag

I am using java sax method to parse xml file, from the example from here, if i have 2 tag with the same name, im able to trace the parent tag, by maintaining my own stack:

using SAX parser, how do you parse an xml file which has same name tags but in different elements?

But my problem is, how can i do the reverse way, i want check, if the parentTag is exist, then check if its childTag exists or not :

if(parentTag is exists)
{
  if(childTag is exists)
  {
  }
}