Let me guess what your exact requirement is. You have listview that displays the data in tamil font, right? You have an edittext where the user a text and that is in tamil, and the searched result is displayed in text view, right?
Instead of implementing your own search solution, I think it's much better to hook into Android's built-in search framework. If you organize your content as a ContentProvider, and declare it to be searchable in the manifest, then you can use the system-wide search box to search for your content.