Java : PipedReader with Examples

PipedReader (Java SE 22 & JDK 22) with Examples.
You will find code examples on most PipedReader methods.

Summary

Piped character-input streams.

Class diagram

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                writer.write("abc");
                TimeUnit.SECONDS.sleep(1);

                writer.write('X');
                TimeUnit.SECONDS.sleep(1);

                writer.write('Y');
                TimeUnit.SECONDS.sleep(1);

                writer.write('Z');
                TimeUnit.SECONDS.sleep(1);

            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });

        executor.submit(() -> {
            try (reader) {
                System.out.println("-- start --");
                while (true) {
                    final var c = reader.read();
                    if (c == -1) {
                        System.out.println("-- end --");
                        break;
                    }

                    System.out.printf("%c%n", c);
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            }
        });
    }
}

// Result
// ↓
//-- start --
//a
//b
//c
//X
//Y
//Z
//-- end --

Fields declared in Reader

lock

Please see the link below.

Reader with Examples

Constructors

PipedReader ()

Creates a PipedReader so that it is not yet connected.

try (final var reader = new PipedReader();
     final var writer = new PipedWriter()) {
    reader.connect(writer);

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                final var list = List.of('a', 'b', 'c', 'd');
                for (final var c : list) {
                    writer.write(c);
                    TimeUnit.SECONDS.sleep(1);
                }
            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });

        executor.submit(() -> {
            try (reader) {
                System.out.println("-- start --");
                while (true) {
                    final var c = reader.read();
                    if (c == -1) {
                        System.out.println("-- end --");
                        break;
                    }

                    System.out.printf("%c%n", c);
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            }
        });
    }
}

// Result
// ↓
//-- start --
//a
//b
//c
//d
//-- end --

PipedReader (int pipeSize)

Creates a PipedReader so that it is not yet connected and uses the specified pipe size for the pipe's buffer.

Please see also : PipedReader()

// Gets the elapsed seconds from the start time.
final long startTime = System.nanoTime();
final DoubleSupplier elapsedTime = () -> (System.nanoTime() - startTime) / 1000000000.0;

try (final var reader = new PipedReader(3);
     final var writer = new PipedWriter(reader)) {

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                final var list = List.of('a', 'b', 'c', 'd', 'e');
                for (final var c : list) {
                    writer.write(c);
                    System.out.printf("write = %c (%f sec.)%n", c, elapsedTime.getAsDouble());
                }
            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            }
        });

        executor.submit(() -> {
            try (reader) {
                while (true) {
                    TimeUnit.SECONDS.sleep(2);

                    final var c = reader.read();
                    if (c == -1) {
                        break;
                    }

                    System.out.printf("read  = %c (%f sec.)%n", c, elapsedTime.getAsDouble());
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });
    }

}

// Result
// ↓
//write = a (0.002390 sec.)
//write = b (0.003750 sec.)
//write = c (0.003882 sec.)
//read  = a (2.014535 sec.)
//write = d (2.029911 sec.)
//read  = b (4.030443 sec.)
//write = e (4.046095 sec.)
//read  = c (6.036116 sec.)
//read  = d (8.042297 sec.)
//read  = e (10.055684 sec.)

PipedReader (PipedWriter src)

Creates a PipedReader so that it is connected to the piped writer src.

try (final var writer = new PipedWriter();
     final var reader = new PipedReader(writer)) {

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                final var list = List.of('a', 'b', 'c', 'd');
                for (final var c : list) {
                    writer.write(c);
                    TimeUnit.SECONDS.sleep(1);
                }
            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });

        executor.submit(() -> {
            try (reader) {
                System.out.println("-- start --");
                while (true) {
                    final var c = reader.read();
                    if (c == -1) {
                        System.out.println("-- end --");
                        break;
                    }

                    System.out.printf("%c%n", c);
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            }
        });
    }
}

// Result
// ↓
//-- start --
//a
//b
//c
//d
//-- end --

PipedReader (PipedWriter src, int pipeSize)

Creates a PipedReader so that it is connected to the piped writer src and uses the specified pipe size for the pipe's buffer.

Please see :

PipedReader(PipedWriter src) for the src parameter.
PipedReader(int pipeSize) for the pipeSize parameter.

Methods

void close ()

Closes this piped stream and releases any system resources associated with the stream.

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write('a');
    System.out.printf("%c%n", reader.read()); // a
}

// An example without a try-with-resources statement.
final var reader = new PipedReader();
try (final var writer = new PipedWriter(reader)) {

    writer.write('a');
    System.out.printf("%c%n", reader.read()); // a
} finally {
    reader.close();
}

void connect (PipedWriter src)

Causes this piped reader to be connected to the piped writer src.

try (final var reader = new PipedReader();
     final var writer = new PipedWriter()) {
    reader.connect(writer);

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                final var list = List.of('a', 'b', 'c', 'd');
                for (final var c : list) {
                    writer.write(c);
                    TimeUnit.SECONDS.sleep(1);
                }
            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });

        executor.submit(() -> {
            try (reader) {
                System.out.println("-- start --");
                while (true) {
                    final var c = reader.read();
                    if (c == -1) {
                        System.out.println("-- end --");
                        break;
                    }

                    System.out.printf("%c%n", c);
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            }
        });
    }
}

// Result
// ↓
//-- start --
//a
//b
//c
//d
//-- end --

int read ()

Reads the next character of data from this piped stream.

try (final var reader = new PipedReader();
     final var writer = new PipedWriter()) {
    reader.connect(writer);

    try (final var executor = Executors.newFixedThreadPool(2)) {

        executor.submit(() -> {
            try (writer) {
                final var list = List.of('a', 'b', 'c', 'd');
                for (final var c : list) {
                    writer.write(c);
                    TimeUnit.SECONDS.sleep(1);
                }
            } catch (IOException e) {
                System.out.println("Writer IOException! : " + e.getMessage());
            } catch (InterruptedException e) {
                System.out.println("InterruptedException!");
            }
        });

        executor.submit(() -> {
            try (reader) {
                System.out.println("-- start --");
                while (true) {
                    final var c = reader.read();
                    if (c == -1) {
                        System.out.println("-- end --");
                        break;
                    }

                    System.out.printf("%c%n", c);
                }
            } catch (IOException e) {
                System.out.println("Reader IOException! : " + e.getMessage());
            }
        });
    }
}

// Result
// ↓
//-- start --
//a
//b
//c
//d
//-- end --

int read (char[] cbuf, int off, int len)

Reads characters into a portion of an array.

final char[] cbuf = {'a', 'b', 'c'};

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write(cbuf);

    final var a = new char[3];
    final var ret = reader.read(a, 0, 1);

    // ret = 1 : [a,  ,  ]
    System.out.printf("ret = %d : %s%n", ret, Arrays.toString(a));
}

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write(cbuf);

    final var a = new char[3];
    final var ret = reader.read(a, 0, 2);

    // ret = 2 : [a, b,  ]
    System.out.printf("ret = %d : %s%n", ret, Arrays.toString(a));
}

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write(cbuf);

    final var a = new char[3];
    final var ret = reader.read(a, 0, 3);

    // ret = 3 : [a, b, c]
    System.out.printf("ret = %d : %s%n", ret, Arrays.toString(a));
}

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write(cbuf);

    final var a = new char[3];
    final var ret = reader.read(a, 1, 2);

    // ret = 2 : [ , a, b]
    System.out.printf("ret = %d : %s%n", ret, Arrays.toString(a));
}

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    writer.write(cbuf);

    final var a = new char[3];
    final var ret = reader.read(a, 2, 1);

    // ret = 1 : [ ,  , a]
    System.out.printf("ret = %d : %s%n", ret, Arrays.toString(a));
}

boolean ready ()

Tell whether this stream is ready to be read.

try (final var reader = new PipedReader();
     final var writer = new PipedWriter(reader)) {

    System.out.println(reader.ready()); // false

    writer.write('a');

    System.out.println(reader.ready()); // true
    System.out.printf("%c%n", reader.read()); // a

    System.out.println(reader.ready()); // false

    writer.write('b');
    writer.write('c');

    System.out.println(reader.ready()); // true
    System.out.printf("%c%n", reader.read()); // b

    System.out.println(reader.ready()); // true
    System.out.printf("%c%n", reader.read()); // c

    System.out.println(reader.ready()); // false
}

Methods declared in Reader

mark, markSupported, nullReader, read, read, reset, skip, transferTo

Please see the link below.

Reader with Examples

API Examples

Java : PipedReader with Examples

Summary

Fields declared in Reader

lock

Constructors

PipedReader ()

PipedReader (int pipeSize)

PipedReader (PipedWriter src)

PipedReader (PipedWriter src, int pipeSize)

Methods

void close ()

void connect (PipedWriter src)

int read ()

int read (char[] cbuf, int off, int len)

boolean ready ()

Methods declared in Reader

mark, markSupported, nullReader, read, read, reset, skip, transferTo

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