CODEWITHSUNDEEP
java
user1663380
user1663380

Reputation: 1013

BufferedReader not returning null at the last line

The last line contains nothing , yet it does not return null. Code is as follows

When debug using Eclipse, I saw line= "" in debug mode, how do I prevent this from happening

BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
   // process the line.
}
br.close();

Upvotes: 3

Views: 4063

Answers (4)

Achintya Jha
Achintya Jha

Reputation: 12843

The BufferedReader.readLine() method returns null when it reaches the end of file.

Your program appears to be reading line in the file before it reaches to the end of the file. The condition for terminating is that line is null, empty string is not null so it loop and dont get terminated.

Upvotes: 4

Remi Morin
Remi Morin

Reputation: 292

nulll = nothing. "" = empty. If the last line is empty "" is expected. The following line should be null.

from there you can test for emptyness (I like the appache StringUtils isEmpty) or remove last \n from your file prior to processing.

Upvotes: 2

Cyrille Ka
Cyrille Ka

Reputation: 15533

You don't prevent it from happening, an empty line is a line, so it will be returned as is.

What you can do is to check if the line is empty before processing:

BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
   if (!line.isEmpty()) {
       // process the line.
   }
}
br.close();

Upvotes: 6

Ivaylo Strandjev
Ivaylo Strandjev

Reputation: 71009

If the line consists of a single line break line will be empty String, but readLine will not return null. readLine only returns null once you reach the end of the file.

Upvotes: 2

Related Questions