Code segment from https://masterex.github.io/archive/2020/07/25/decorator-design-pattern-synergies.html

OutputStreamAdapter.java

public class OutputStreamAdapter extends OutputStream implements Appendable, Closeable {

    private OutputStream os;
    private CheckedOutputStream cos;
    private DeflaterOutputStream dos;
    private Appendable appendable;
    private PrintStream pos;

    public OutputStreamAdapter(OutputStream os) {
        setOutputStream(os);
    }

    public void addOutputStream(OutputStream o) {
        setOutputStream(o);
    }

    private void setOutputStream(OutputStream o) {
        os = o;
        if (o instanceof CheckedOutputStream) {
            cos = (CheckedOutputStream) o;
        }
        if (o instanceof DeflaterOutputStream) {
            dos = (DeflaterOutputStream) o;
        }
        if (o instanceof Appendable) {
            appendable = (Appendable) o;
        }
        if (o instanceof PrintStream) {
            pos = (PrintStream) o;
        }
    }

    @Override
    public void write(int i) throws IOException {
        os.write(i);
    }

    public Checksum getChecksum() {
        if (cos != null) {
            return cos.getChecksum();
        } else if (os instanceof OutputStreamAdapter) {
            return ((OutputStreamAdapter) os).getChecksum();
        }
        throw new UnsupportedOperationException("Decorator method not implemented.");
    }

    public void finish() throws IOException {
        if (dos != null) {
            dos.finish();
        } else if (os instanceof OutputStreamAdapter) {
            ((OutputStreamAdapter) os).finish();
        }
        throw new UnsupportedOperationException("Decorator method not implemented.");
    }

    @Override
    public void flush() throws IOException {
        os.flush();
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        os.write(b, off, len);
    }

    @Override
    public void write(byte[] b) throws IOException {
        System.out.println("WRITE!");
        os.write(b);
    }

    @Override
    public void close() throws IOException {
        os.close();
    }

    @Override
    public Appendable append(CharSequence cs) throws IOException {
        if (appendable != null) {
            appendable.append(cs);
        }
        throw new UnsupportedOperationException("Decorator method not implemented.");
    }

    @Override
    public Appendable append(CharSequence cs, int i, int i1) throws IOException {
        if (appendable != null) {
            appendable.append(cs, i, i1);
        }
        throw new UnsupportedOperationException("Decorator method not implemented.");
    }

    @Override
    public Appendable append(char c) throws IOException {
        if (appendable != null) {
            appendable.append(c);
        }
        throw new UnsupportedOperationException("Decorator method not implemented.");
    }

    public void println(String x) {
        if (pos != null) {
            pos.println(x);
        } else {
            throw new UnsupportedOperationException("Decorator method not implemented.");
        }
    }

}