As Der Golem has stated just use file[i] however you will also need to declare listAdapter before your for loop or it will re-assign the values each time you iterate through the loop!
Here's a quick guide that should help you:
mainListView = (ListView) findViewById( R.id.mainListView );
ArrayList<String> planetList = new ArrayList<String>();
// Create ArrayAdapter using the planet list.
listAdapter = new ArrayAdapter<String>(this, R.layout.simplerow, planetList);
for (int i=0; i < file.length; i++)
{
listAdapter.add(file[i].getName());
}
// Set the ArrayAdapter as the ListView's adapter.
mainListView.setAdapter( listAdapter );
Log.d("Files", "FileName:" + file[i].getName());
Toast.makeText(getApplicationContext(), file[i].getName(),Toast.LENGTH_LONG).show();
Hope this helps.