import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;


public class Test {
  public class WritingClass {
    public DataOutputStream dos;
    public DataInputStream dis;

    public WritingClass(File output, File input) throws FileNotFoundException {
      dos = new DataOutputStream(new FileOutputStream(output));
      dis = new DataInputStream(new FileInputStream(output));
    }

    public String writeThis(String str) throws IOException {
      dos.writeUTF(str);
      String response = dis.readUTF();
      return response;
    }
  }

  public class ReadingClass {
    public DataOutputStream dos;
    public DataInputStream dis;

    public ReadingClass(File output, File input) throws FileNotFoundException {
      dos = new DataOutputStream(new FileOutputStream(output));
      dis = new DataInputStream(new FileInputStream(output));
    }

    public String readThat() throws IOException {
      String read = dis.readUTF();
      dos.writeUTF("nice string");
      return read;
    }
  }

  public Test() throws IOException {
    final File output = new File("out.txt");
    if(!output.exists())
      output.createNewFile();
    final File input = new File("in.txt");
    if(!input.exists())
      input.createNewFile();

    final WritingClass wc = new WritingClass(output, input);
    final ReadingClass rc = new ReadingClass(output, input);

    Thread writeThread = new Thread() {
      @Override
      public void run() {
        System.out.println("writeThread > Starting..");
        try {
          String testStr = "test";
          String reponse = wc.writeThis(testStr);
          System.out.printf("writeThread > wrote: %s, response%n", testStr, reponse);
        } catch(Exception ex) {
          System.out.println("writeThread > Exception");
          ex.printStackTrace();
        }
        System.out.println("writeThread > Stopping..");
      }
    };
    Thread readThread = new Thread() {
      @Override
      public void run() {
        System.out.println(" readThread > Starting writeThread..");
        try {
          System.out.printf(" readThread > read: %s%n", rc.readThat());
        } catch(Exception ex) {
          System.out.println(" readThread > Exception");
          ex.printStackTrace();
        }
        System.out.println(" readThread > Stopping..");
      }
    };
    writeThread.start();
    readThread.start();
  }


  public static void main(String[] args) throws Exception {
    Test t = new Test();
  }
}