Module java.base
Package java.io

Class PipedInputStream

java.lang.Object
java.io.InputStream
java.io.PipedInputStream
All Implemented Interfaces:
Closeable, AutoCloseable

public class PipedInputStream extends InputStream
A piped input stream should be connected to a piped output stream; the piped input stream then provides whatever data bytes are written to the piped output stream. Typically, data is read from a PipedInputStream object by one thread and data is written to the corresponding PipedOutputStream by some other thread. Attempting to use both objects from a single thread is not recommended, as it may deadlock the thread. The piped input stream contains a buffer, decoupling read operations from write operations, within limits. A pipe is said to be broken if a thread that was providing data bytes to the connected piped output stream is no longer alive.
Since:
1.0
See Also:
PipedOutputStream
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected byte[]
    The circular buffer into which incoming data is placed.
    protected int
    The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream.
    protected int
    The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.
    protected static final int
    The default size of the pipe's circular input buffer.
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates a PipedInputStream so that it is not yet connected.
    PipedInputStream​(int pipeSize)
    Creates a PipedInputStream so that it is not yet connected and uses the specified pipe size for the pipe's buffer.
    Creates a PipedInputStream so that it is connected to the piped output stream src.
    PipedInputStream​(PipedOutputStream src, int pipeSize)
    Creates a PipedInputStream so that it is connected to the piped output stream src and uses the specified pipe size for the pipe's buffer.
  • Method Summary

    Modifier and Type
    Method
    Description
    int
    Returns the number of bytes that can be read from this input stream without blocking.
    void
    Closes this piped input stream and releases any system resources associated with the stream.
    void
    Causes this piped input stream to be connected to the piped output stream src.
    int
    Reads the next byte of data from this piped input stream.
    int
    read​(byte[] b, int off, int len)
    Reads up to len bytes of data from this piped input stream into an array of bytes.
    protected void
    receive​(int b)
    Receives a byte of data.

    Methods declared in class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • PIPE_SIZE

      protected static final int PIPE_SIZE
      The default size of the pipe's circular input buffer.
      Since:
      1.1
      See Also:
      Constant Field Values
    • buffer

      protected byte[] buffer
      The circular buffer into which incoming data is placed.
      Since:
      1.1
    • in

      protected int in
      The index of the position in the circular buffer at which the next byte of data will be stored when received from the connected piped output stream. in < 0 implies the buffer is empty, in == out implies the buffer is full
      Since:
      1.1
    • out

      protected int out
      The index of the position in the circular buffer at which the next byte of data will be read by this piped input stream.
      Since:
      1.1
  • Constructor Details

    • PipedInputStream

      public PipedInputStream(PipedOutputStream src) throws IOException
      Creates a PipedInputStream so that it is connected to the piped output stream src. Data bytes written to src will then be available as input from this stream.
      Parameters:
      src - the stream to connect to.
      Throws:
      IOException - if an I/O error occurs.
    • PipedInputStream

      public PipedInputStream(PipedOutputStream src, int pipeSize) throws IOException
      Creates a PipedInputStream so that it is connected to the piped output stream src and uses the specified pipe size for the pipe's buffer. Data bytes written to src will then be available as input from this stream.
      Parameters:
      src - the stream to connect to.
      pipeSize - the size of the pipe's buffer.
      Throws:
      IOException - if an I/O error occurs.
      IllegalArgumentException - if pipeSize <= 0.
      Since:
      1.6
    • PipedInputStream

      public PipedInputStream()
      Creates a PipedInputStream so that it is not yet connected. It must be connected to a PipedOutputStream before being used.
    • PipedInputStream

      public PipedInputStream(int pipeSize)
      Creates a PipedInputStream so that it is not yet connected and uses the specified pipe size for the pipe's buffer. It must be connected to a PipedOutputStream before being used.
      Parameters:
      pipeSize - the size of the pipe's buffer.
      Throws:
      IllegalArgumentException - if pipeSize <= 0.
      Since:
      1.6
  • Method Details

    • connect

      public void connect(PipedOutputStream src) throws IOException
      Causes this piped input stream to be connected to the piped output stream src. If this object is already connected to some other piped output stream, an IOException is thrown.

      If src is an unconnected piped output stream and snk is an unconnected piped input stream, they may be connected by either the call:

      snk.connect(src) 

      or the call:

      src.connect(snk) 

      The two calls have the same effect.

      Parameters:
      src - The piped output stream to connect to.
      Throws:
      IOException - if an I/O error occurs.
    • receive

      protected void receive(int b) throws IOException
      Receives a byte of data. This method will block if no input is available.
      Parameters:
      b - the byte being received
      Throws:
      IOException - If the pipe is broken, unconnected, closed, or if an I/O error occurs.
      Since:
      1.1
    • read

      public int read() throws IOException
      Reads the next byte of data from this piped input stream. The value byte is returned as an int in the range 0 to 255. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.
      Specified by:
      read in class InputStream
      Returns:
      the next byte of data, or -1 if the end of the stream is reached.
      Throws:
      IOException - if the pipe is unconnected, broken, closed, or if an I/O error occurs.
    • read

      public int read(byte[] b, int off, int len) throws IOException
      Reads up to len bytes of data from this piped input stream into an array of bytes. Less than len bytes will be read if the end of the data stream is reached or if len exceeds the pipe's buffer size. If len is zero, then no bytes are read and 0 is returned; otherwise, the method blocks until at least 1 byte of input is available, end of the stream has been detected, or an exception is thrown.
      Overrides:
      read in class InputStream
      Parameters:
      b - the buffer into which the data is read.
      off - the start offset in the destination array b
      len - the maximum number of bytes read.
      Returns:
      the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
      Throws:
      NullPointerException - If b is null.
      IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
      IOException - if the pipe is broken, unconnected, closed, or if an I/O error occurs.
      See Also:
      InputStream.read()
    • available

      public int available() throws IOException
      Returns the number of bytes that can be read from this input stream without blocking.
      Overrides:
      available in class InputStream
      Returns:
      the number of bytes that can be read from this input stream without blocking, or 0 if this input stream has been closed by invoking its close() method, or if the pipe is unconnected, or broken.
      Throws:
      IOException - if an I/O error occurs.
      Since:
      1.0.2
    • close

      public void close() throws IOException
      Closes this piped input stream and releases any system resources associated with the stream.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class InputStream
      Throws:
      IOException - if an I/O error occurs.