Runtime error on Integer.parseInt(); i am trying to compare the content in the file and the new value obtained from the method - exception

Question

/*the below code is i am trying for the notification of new mail i am trying to fetch the prestored value into the file and compare it to the new value from the method
public static void main(String args[]) throws MessagingException{
try {
Notification n= new Notification();
int a =n.Notification();
BufferedReader br = null;
//read from the earlier file value of the total messages
String sCurrentLine;
br = new BufferedReader(new FileReader("Notification.txt"));
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
}
int b = Integer.parseInt(sCurrentLine);
if (a>b){
System.out.println("you have "+(a-b)+" new Messsages");
}else{
System.out.println("NO New message");
}
//write the new value of the total messages to the file
Writer output = null;
File file = new File("Notification.txt");
output = new BufferedWriter(new FileWriter(file, true));
output.write(String.valueOf(a));
output.close();
} catch (IOException ex) {
Logger.getLogger(Notification.class.getName()).log(Level.SEVERE, null, ex);
}
}

Answer 1

If the file you are reading from only contains a number that you require, maybe this is what you have to do:
if ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
int b = Integer.parseInt(sCurrentLine);
// do other stuff
}
else
{
// file empty
}