Check if a file contains a string

I recently wrote some java code to check if a file contains a string.

public class FileUtilities {

 
   /**
    * Returns true if the file exists and contains aString, false otherwise.
    * @param file
    * @param aString
    * @return
    * @throws FileNotFoundException
    */
   public static boolean fileContainsString(File file, String aString) throws FileNotFoundException{
  
      FileInputStream fis = null;
      BufferedReader in = null;
  
      try{
         fis = new FileInputStream(file);
         in = new BufferedReader(new InputStreamReader(fis));
   
         String currentLine = "";
         while ((currentLine = in.readLine()) != null) {
            if(currentLine.indexOf(aString) > 0)  return true;
         }
   
      }catch(IOException ioe){
         ioe.printStackTrace();
      }finally{
         try{
            if(in != null) in.close();
            if(fis != null) fis.close();
         }catch(IOException ioe){ }
      }
      return false;
   } 
}