infinite while loop using bufferedreader

Question

I am having a code to store the log files to a SD card in android. The following is the code.

process = Runtime.getRuntime().exec("logcat "+ LOG_TAG +":D *:S");
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
StringBuilder log = new StringBuilder();
String line;
while ((line = bufferedReader.readLine()) != null) {
    //do something over here
}

It is running an infinite loop. Any help.

Look here http://stackoverflow.com/questions/804951/is-it-possible-to-read-from-a-inputstream-with-a-timeout - blocking read will not do, you need either `available()` or a timeout. — Joop Eggen, Aug 21 '14 at 09:06
It's not running an infinite loop. The loop exits when the peer disconnects. — user207421, Aug 21 '14 at 09:34
@EJP: Yes, it exits when the device gets disconnected. But what if I want some code to execute after the while loop. — inquisitive, Aug 21 '14 at 09:58
@Joop Eggen: Thanks.. how can I use `available()` with BufferedReader object. — inquisitive, Aug 21 '14 at 09:59
@Anshu I have turned it into an answer, beause of the code. available is a bit tricky, but might just do here. — Joop Eggen, Aug 21 '14 at 11:07
@Joop So you have to change the while loop not to read until end of stream. — user207421, Aug 22 '14 at 00:09
@EJP no, see answer, wrap the original inputstream in a selfmade one, lying that it is finished with -1 on `available() == 0`. — Joop Eggen, Aug 22 '14 at 06:21

score 1 · Accepted Answer · answered Aug 21 '14 at 11:04

As logCat never ends, you might try to force an end when InputStream.available() == 0. I did this using wrapping the original InputStream in an ImpatientInputStream.

As at the very first start available might be 0 because of the non-blocking nature, you might add a flag whether something read already.

BufferedReader bufferedReader = new BufferedReader(
        new InputStreamReader(
            new ImpatientInputStream(process.getInputStream())
        ));


public class ImpatientInputStream extends InputStream {

    private final InputStream in;
    private boolean eof;

    public ImpatientInputStream(InputStream in) {
        this.in = in;
    }

    @Override
    public int read() throws IOException {
        if (eof) {
            return -1; 
        }
        if (available() == 0) {
            eof = true;
            return -1;
        }
        return in.read();
    }

}

score 0 · Answer 2 · edited May 23 '17 at 12:21

0

logcat never stops, it waits for the next line to display, so readLine() blocks while waiting for the next input from the process.

You can however redirect the output of the command directly with -f filename as explained here.

This answer has everything you need.

edited May 23 '17 at 12:21

Community

1
1

answered Aug 21 '14 at 09:06

Djon

2,230
14
19

I referred that already.. Doing so, the file is created but no data comes in the file doing this way.. – inquisitive Aug 21 '14 at 10:01

score 0 · Answer 3 · answered Aug 21 '14 at 09:36

You can provide timestamp/time period in while loop. Below sample will make this more clear

Sample :

        while (System.currentTimeMillis() < end_time) {
        //do your stuffs here

        while ((line = bufferedReader.readLine()) != null) {
       //do something over here
        }
        }

infinite while loop using bufferedreader

3 Answers3