Writing to a file using PipedWriter in Java

22 Sep 2023

fileio

In Java, the PipedWriter class is used to write data into a pipe. A pipe is a communication channel that connects two threads: one for writing and another for reading. This allows for easy communication between threads in a Java program.

Here’s an example code that demonstrates how to use PipedWriter to write data into a file:

import java.io.*;

public class FileWriterExample {
    public static void main(String[] args) {
        try {
            // Create a PipedWriter and connect it to a PipedReader
            PipedWriter writer = new PipedWriter();
            PipedReader reader = new PipedReader(writer);
            
            // Create a BufferedWriter for writing into a file
            BufferedWriter fileWriter = new BufferedWriter(new FileWriter("output.txt"));

            // Create a separate thread to read from the pipe and write to the file
            Thread readerThread = new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        int data;
                        while ((data = reader.read()) != -1) {   // Read from the pipe
                            fileWriter.write(data);   // Write to the file
                            fileWriter.flush();
                        }
                        fileWriter.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });

            readerThread.start();

            // Write some data to the pipe
            writer.write("Hello, World!");

            // Close the writer to signal the end of data
            writer.close();

            // Wait for the reader thread to finish
            readerThread.join();
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }
}

In the code above, we first create a PipedWriter and connect it to a PipedReader. Then, we create a BufferedWriter that writes data into a file named “output.txt”.

We then create a separate thread that continuously reads from the pipe using the PipedReader and writes the data into the file using the BufferedWriter. The main thread writes the data “Hello, World!” into the pipe using the write() method of PipedWriter.

Finally, we close the PipedWriter to indicate that no more data will be written, and wait for the reader thread to finish before exiting the program.

That’s it! Now you know how to use PipedWriter to write data into a file in Java. Try running the code and check the “output.txt” file to see the result.

#java #fileio