BufferedReader not stating 'ready' when it should

fgysin reinstate Monica picture fgysin reinstate Monica · Jan 21, 2011 · Viewed 13.5k times · Source

I am trying to read text from a web document using a BufferedReader over an InputStreamReader on an URL (to the file on some Apache server).

String result = "";
URL url = new URL("http://someserver.domain/somefile");
BufferedReader in = null;
in = new BufferedReader(new InputStreamReader(url.openStream(), "iso-8859-1"));

result += in.readLine();

Now this works just fine. But Obviously I'd like the reader not to just read one line, but as many as there are in the file.
Looking at the BufferedReader API the following code should do just that:

while (in.ready()) {
    result += in.readLine();
}

I.e. read all lines while there are more lines, stop when no more lines are there. This code does not work however - the reader just never reports ready() = true!

I can even print the ready() value right before reading a line (which reads the correct string from the file) but the reader will report 'false'.

Am I doing something wrong? Why does the BufferedReader return 'false' on ready when there is actually stuff to read?

Answer

josefx picture josefx · Jan 21, 2011

ready() != has more

ready() does not indicate that there is more data to be read. It only shows if a read will could block the thread. It is likely that it will return false before you read all data.

To find out if there is no more data check if readLine() returns null.

String line = in.readLine();
while(line != null){
   ...
   line = in.readLine();
}