Java : PipedReader with Examples
Last Modified : June 3, 2023 Published : May 8, 2023
PipedReader (Java SE 19 & JDK 19) API Examples.
You will find code examples on most PipedReader methods.
Summary
Piped character-input streams.
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
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()
final long current = System.nanoTime();
final DoubleSupplier elapsedTime = () -> (System.nanoTime() - current) / 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 src parameter.
- PipedReader(int pipeSize) for 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.
Please see PipedReader().
int read ()
Reads the next character of data from this piped stream.
Please see PipedReader().
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.
Related posts
- API Examples