Java NIO Pipe

Creating a Pipe
Writing to a Pipe
Reading from a Pipe

Jakob Jenkov Last update: 2014-06-23

A Java NIO Pipe is a one-way data connection between two threads. A

Pipe

has a source channel and a sink channel. You write data to the sink channel. This data can then be read from the source channel.

Here is an illustration of the

Pipe

principle:

Java NIO: Pipe Internals

Creating a Pipe

You open a

Pipe

by calling the

Pipe.open()

method. Here is how that looks:

Pipe pipe = Pipe.open();

Writing to a Pipe

To write to a

Pipe

you need to access the sink channel. Here is how that is done:

Pipe.SinkChannel sinkChannel = pipe.sink();

You write to a

SinkChannel

by calling it's

write()

method, like this:

String newData = "New String to write to file..." + System.currentTimeMillis();

ByteBuffer buf = ByteBuffer.allocate(48);
buf.clear();
buf.put(newData.getBytes());

buf.flip();

while(buf.hasRemaining()) {
sinkChannel.write(buf);
}

Reading from a Pipe

To read from a

Pipe

you need to access the source channel. Here is how that is done:

Pipe.SourceChannel sourceChannel = pipe.source();

To read from the source channel you call its

read()

method like this:

ByteBuffer buf = ByteBuffer.allocate(48);

int bytesRead = inChannel.read(buf);

The

int

returned by the

read()

method tells how many bytes were read into the buffer.