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Java IO: PipedWriter

Jakob Jenkov
Last update: 2015-09-07

The Java PipedWriter class ( makes it possible to write to a Java pipe as a stream of characters. In that respect the PipedWriter works much like a PipedOutputStream except that a PipedOutputStream is byte based, whereas a PipedWriter is character based. The PipedWriter is intended for writing text, in other words.

Normally a Java PipedWriter is connected to a PipedReader. And often the PipedWriter and the PipedReader are used by different threads.

PipedWriter Example

Here is a simple Java PipedWriter example:

PipedWriter pipedWriter = new PipedWriter();

while(moreData()) {
  int data = getMoreData();

Note: The proper exception handling has been skipped here for the sake of clarity. To learn more about correct exception handling, go to Java IO Exception Handling.


The write() method of a PipedWriter takes an int which contains the byte value of the byte to write. There are also versions of the write() method that take a String, char array etc.

Java IO Pipes

The PipedWriter must always be connected to a PipedReader. When connected like that, they form a Java pipe. To learn more about Java pipes, go to Java IO: Pipes.

Closing a PipedWriter

When you are finished writing characters to a Java PipedWriter you should remember to close it. Closing a PipedWriter is done by calling its close() method. Here is how closing a Java PipedWriter looks:


You can also use the try-with-resources construct introduced in Java 7. Here is how to use and close a PipedWriter looks with the try-with-resources construct:

try(PipedWriter pipedWriter =
    new PipedWriter(){

    pipedWriter.write("data 1");
    pipedWriter.write("data 2");
    pipedWriter.write("data 3");


Notice how there is no longer any explicit close() method call to the PipedWriter instance. The try-with-resources construct takes care of that.

Jakob Jenkov

Copyright  Jenkov Aps
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