Retrieve repository file name details

Hi All,
In my project a situation like when we pass 'repository file names' as the only input, i need to get itemID of that filename.(i.e. reversal direction).

for eg, when i give file name as 'sampleone.c' i need the itemID of the file name. Is there any code in java API to retrieve those information.

Kindly correct me if i'm wrong.I hardly need this bcoz, accessing elements from top to bottom takes more time in loading the details.

Thanks.