how to check object of bufferreader is null or not in junit code example

Example: java read file bufferedreader

try {
	File file = new File("data.txt");
	BufferedReader reader = new BufferedReader(new FileReader(file));
	String line;

	while((line = reader.readLine()) != null) {
	 	 System.out.println(line);
	}
} catch(IOException e) {
  	e.printStackTrace();
}