How to notify PipedInputStream thread that PipedOutputStream thread has written last byte?

Yes, closing the PipedOutputStream results in a -1 on the PipedInputStream.

Looks pretty graceful to me! Here's my SSCCE:

import java.io.*;import java.nio.charset.*;public class SOPipe{    public static void main(String[] args) throws Exception    {        PipedOutputStream os = new PipedOutputStream();        PipedInputStream is = new PipedInputStream(os);        ReaderThread readerThread = new ReaderThread(is);        WriterThread writerThread = new WriterThread(os);        readerThread.start();        writerThread.start();        readerThread.join();        writerThread.join();        System.out.println("Both Reader and Writer completed.");        System.out.println("Main method returning normally now.");    }    private static final Charset LATIN1 = Charset.forName("latin1");    public static class WriterThread extends Thread    {        private final PipedOutputStream _os;        public WriterThread(PipedOutputStream os)        {            _os = os;        }        public void run()        {            try            {                String msg = "Ceci n'est pas une pipe";                byte[] msgBytes = msg.getBytes(LATIN1);                System.out.println("WriterThread sending message: " + msg);                for(int i = 0; i < msgBytes.length; i++)                {                    _os.write(msgBytes, i, 1);                    System.out.println("WriterThread wrote a byte!");                    _os.flush();                }                _os.close();                System.out.println("[COMPLETED] WriterThread");            }            catch (Exception e)            {                e.printStackTrace();            }        }    }    public static class ReaderThread extends Thread    {        private final PipedInputStream _is;        public ReaderThread(PipedInputStream is)        {            _is = is;        }        public void run()        {            try            {                ByteArrayOutputStream baos = new ByteArrayOutputStream();                byte[] buffer = new byte[1];                int read;                while ((read = _is.read(buffer, 0, 1)) != -1)                {                    System.out.println("ReaderThread read a byte!");                    baos.write(buffer, 0, read);                }                System.out.println("[COMPLETED] ReaderThread; received: "                         + new String(baos.toByteArray(), LATIN1));                _is.close();            }            catch (Exception e)            {                e.printStackTrace();            }        }    }}

It is enough just to close output stream.

You can extend PipedOutputStream class & override its write() method to add your custom logic, after it has written all the bytes to the piped output stream.

    public class CustomPipedOutput extends PipedOutputStream {          @Override          public void write(byte[] byteArray, int offset, int length){            super.write(byteArray, offset, length);            //-- Code to be executed after writing bytes          }          @Override          public void close(){            super.close();            //-- Code to be executed after closing piped input stream          }   }

Similarly, can extend other methods if required accordingly.