Problem reading in data to populate table

[Mr.David Shapiro]

Hello,

I am having a problem with some code where I read in a file with data to create a table, but it drops some of the lines or something (e.g., lose a table TR or a TD or whatever). I used java.net.URL to open and read the file called monitor.out that has in it lines like:

TR
TDstuff/TD
TDmore/TD
TDand more/TD
/TR

Note: Removed greater than/less than signs around html code so I can post here
.
.
.


It will drop the first TR and throws it all off. Am I using the right method to read in a file to populate a table? Is there something else going on?

/* file does exist so display data */
java.net.URL url =config.getServletContext().getResource("/monitor.out");
BufferedReader br =new BufferedReader(new InputStreamReader(url.openStream()));
%
TABLE width='100%' border='0' cellspacing='0' cellpadding='0'
TR
TH /TH
THLoginable/TH
THPingable/TH
THApplication/TH
/TR %
while (br.readLine() != null) {
line = br.readLine();
if (line != null) { // not sure why but I get a null line
out.println(line);
}
} %
/TABLE %

[Ernest Friedman-Hill]

Hi,

Welcome to JavaRanch!

Here's your code with some explanatory comments

while (br.readLine() != null) { [B] // Reads a line and discards it! [/B]
  line = br.readLine();         [B] // Reads another line [/B]
  if (line != null) {           [B] // readLine() returns null at end-of-file [/B]
    out.println(line);
}

You're discarding every second line, because you read two lines for each loop iteration! The right way to write this loop:

String line;
while ((line = br.readLine()) != null) { 
    out.println(line);
}

Some people don't like that complicated loop condition; an alternative, then, is to write:

String line = br.readLine();
while (line != null) { 
    out.println(line);
    line = br.readLine();
}

Finally, I don't know why you posted this in our Linux forum; we have other forums, like JSP or even Java in General, that would have been more appropriate.

[David Dong]

that is a very common mistake!! Don't read twice.. make sure you call readLine once..