How to Stop Producer Thread and Consumer Thread in case FileNotException occurs

Question

I am reading a csv file from a location.

Could you please tell me how can I stop the Producer Thread and Consumer Thread incase file is not found in this case ?

Below is my program which creates two threads, Producer and Consumer Threads to read the data from the file

package com.util;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.PipedReader;
import java.io.PipedWriter;
import au.com.bytecode.opencsv.CSVReader;

public class TestProgram {
    public static void main(String args[]) {
        final String startToken = ",Nifty 50 Gainers";
        final String endToken = "50 Losers";
        final PipedWriter pipedWriter = new PipedWriter();
        PipedReader pipedReaderTmp = null;
        try {
            pipedReaderTmp = new PipedReader(pipedWriter);
        } catch (IOException e) {
        }
        final PipedReader pipedReader = pipedReaderTmp;
        // Consumer
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    CSVReader csvReader = new CSVReader(pipedReader);
                    while (true) {
                        String[] line = csvReader.readNext(); // blocks until the next line is available
                        if (line == null)
                            break; // end of stream has been reached
                        if (line != null && line.length > 3) {
                            String indices_name = line[1];
                            if (indices_name != null) {

                                System.out.println(indices_name);
                            }

                        }
                    }

                } catch (IOException e) {
                    e.printStackTrace();
                } catch (Exception e) {

                    e.printStackTrace();
                }
            }
        }).start();

        // Producer
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    BufferedReader br = new BufferedReader(new FileReader(
                            "C:\\Users\\ravikiranv\\Downloads\\MA050116.csv"));
                    String line = null;
                    while ((line = br.readLine()) != null) {
                        if (startToken.equals(line))
                            break;
                    }
                    while ((line = br.readLine()) != null) {
                        if (line.contains((endToken))) {
                            break;
                        } else {
                            pipedWriter.write(line + '\n');
                        }
                    }
                    pipedWriter.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

score 1 · Accepted Answer · edited May 23 '17 at 12:23

1

See the Javadoc for PipedReader.read().

Throws: IOException - if the pipe is broken, unconnected, closed, or an I/O error occurs.

So just close it and the other end wwil get an IOException.

Note: The PipedReader has some issues - you may find it safer/better to use something like a `BlockingQueue.

edited May 23 '17 at 12:23

Community

1
1

answered Jan 19 '16 at 16:03

OldCurmudgeon

64,482
16
119
213

score 0 · Answer 2 · edited May 23 '17 at 11:44

You can and should instantiate and start the Threads only if you know the file exists. This keeps you safe from the concerns to stop threads from within.

File file = new File("C:\\Users\\ravikiranv\\Downloads\\MA050116.csv");

if (file.exists()) {
     new Thread(new Runnable() { ... }).start();
     ...
}

If you don't want that for a reason, you could keep a reference to the consumer thread and stop it from within the producer. For an example how to do that, see this answer

How to Stop Producer Thread and Consumer Thread in case FileNotException occurs

2 Answers2