Java - convert OutputStream to InputStream

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// Note: in the example, InputStream waits until data is available.


// ------------------------------------------------------------
// Program.java file:
// ------------------------------------------------------------

import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;

public class Program {

    public static void main(String[] args) throws IOException {

        CombinedStream combinedStream = new CombinedStream();

        OutputStream outputStream = combinedStream.getOutputStream();
        InputStream inputStream = combinedStream.getInputStream();

        outputStream.write(new byte[] {1, 2, 3, 4, 5});

        byte[] inputData = new byte[5];               // {0, 0, 0, 0, 0}
        int readCount = inputStream.read(inputData);  // 5
                                                      // {1, 2, 3, 4, 5}
    }
}



// ------------------------------------------------------------
// CombinedStream.java file:
// ------------------------------------------------------------

import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingDeque;

public static class CombinedStream {

    private BlockingQueue<Integer> queue = new LinkedBlockingDeque<>();

    private OutputStream outputStream = null;
    private InputStream inputStream = null;

    public OutputStream getOutputStream() {
        if (this.outputStream == null) {
            this.outputStream = new OutputStream() {
                @Override
                public void write(int value) throws IOException {
                    queue.add(value);
                }
            };
        }
        return this.outputStream;
    }

    public InputStream getInputStream() {
        if (this.inputStream == null) {
            this.inputStream = new InputStream() {
                @Override
                public int read() throws IOException {
                    try {
                        return queue.take();  // returns byte or waits until byte is available
                    } catch (InterruptedException e) {
                        throw new IOException("Input stream interrupted.", e);
                    }
                }
            };
        }
        return this.inputStream;
    }
}



// Hint: to read and return only available data without waiting use this source code as InputStream:
/*
    public InputStream getInputStream() {
        if (this.inputStream == null) {
            this.inputStream = new InputStream() {
                @Override
                public int read() throws IOException {
                    Integer value = queue.poll();
                    if (value == null) {
                        return -1;
                    }
                    return value;
                }
            };
        }
        return this.inputStream;
    }
*/