import java.io.*;

public class PipedStreamTest {

    /**
     *
     * @param args
     *
     */
    public static void main(String[] args) {
// TODO Auto-generated method stub
        Sender t1 = new Sender();
        Receiver t2 = new Receiver();
        PipedOutputStream os = t1.getOutput(); //The method getOutput() is undefined for the type Thread
        PipedInputStream is = t2.getInput(); //The method getInput() is undefined for the type Thread
        try {
            is.connect(os);
        } catch (IOException e) {
            e.printStackTrace();
        }

        t1.start();

        t2.start();
    }
}

class Sender extends Thread {

    private PipedOutputStream out = new PipedOutputStream();

    public PipedOutputStream getOutput() {
        return out;
    }

    public void run() {
        try {
            out.write("hello".getBytes());
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class Receiver extends Thread {

    private PipedInputStream in = new PipedInputStream();

    public PipedInputStream getInput() {
        return in;
    }

    public void run() {
        byte[] buf = new byte[1024];
        try {
            int len = in.read(buf);
            System.out.println("receive from sender:\n" + new String(buf, 0, len));
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

------解决方案--------------------

你定义的类型不对