java PipedReader和PipedWriter用法

import java.io.PipedReader;
import java.io.PipedWriter;
import java.io.Reader;
import java.io.Writer;
import java.io.BufferedReader;
import java.io.InputStreamReader;

class ReadThread extends Thread
{
        private PipedReader reader;

        public ReadThread(PipedReader reader)
        {
                this.reader = reader;
        }

        public void run()
        {
                char[] data = new char[1024];
                int len;

                while (true)
                {
                        try
                        {
                                len = reader.read(data, 0, data.length);
                                if (len == -1)
                                        break;
                                else
                                        System.out.println(new String(data, 0, len));
                        }
                        catch(Exception e)
                        {
                                e.printStackTrace();
                        }
                }
        }
}

public class tmp
{
        public static void main(String args[]) throws Exception
        {
                PipedReader reader = new PipedReader();
                PipedWriter writer = new PipedWriter();

                ReadThread t = new ReadThread(reader);
                t.start();

                writer.connect(reader);

                BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
                char[] data = new char[1024];
                int len;

                while (true)
                {
                        len = in.read(data, 0, data.length);
                        if (len == -1)
                                break;
                        else
                                writer.write(data, 0, len);
                }

                in.close();
                writer.flush();
                writer.close();
                reader.close();
        }
}