Null pointer exception in bufferedreader

Asked Jun 12 '16 at 15:39

Active Jun 12 '16 at 15:39

Viewed 41 times

In the sample code below, why does a null pointer exception get thrown when I try to get the value of string two? The code works fine without br.close(). Is there some concept of BufferedReader that I am missing?

 public String readString() throws IOException {
   BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
   String s="";
   s=br.readLine();
   br.close();
   return s;

}

public static void main(String[] args) throws IOException {
Test obj = new Test();
String one = obj.readString();
String two = obj.readString();

}

asked Jun 12 '16 at 15:39

learn_code

[Couldn't reproduce](http://melpon.org/wandbox/permlink/hsV0fhGyA8PMlMVy). – MikeCAT Jun 12 '16 at 15:40
1

Never close `System.in` or a Reader that uses it. That's a very dangerous thing to do, and has been addressed here many times. – Hovercraft Full Of Eels Jun 12 '16 at 15:40
Instead create your BufferedReader or Scanner and pass it to where it's needed. – Hovercraft Full Of Eels Jun 12 '16 at 15:42
Oh. Thank you. I was not aware of that. Is there a better way to do it? I thought we are supposed to close the BufferedReader once we are done with it. I'm not too much into programming. – learn_code Jun 12 '16 at 15:42
Yes, close it when you the application is *completely* done with `System.in` but not before. `System.in` is somewhat special. – Hovercraft Full Of Eels Jun 12 '16 at 15:44

Null pointer exception in bufferedreader

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