Problem in transporting Key

I am coding a program to transmit public key from a client to server.

Code :

// SERVER
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.Security;
import javax.crypto.Cipher;
import java.io.*;
import java.net.*;
class server
{
public static void main(String a[])throws Exception
{
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC");
    ServerSocket ss=new ServerSocket(4321);
    Socket s=ss.accept();
    BufferedReader in=new BufferedReader(new InputStreamReader(s.getInputStream()));
    System.out.println(in.readLine());
    s.close();
    ss.close();
}
}

Code :

// CLIENT
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.Security;
import javax.crypto.Cipher;
import java.io.*;
import java.net.*;
class client
{
public static void main(String a[])throws Exception
{
    Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
    Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC");
    SecureRandom random = new SecureRandom();
    KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC");
    generator.initialize(512, random);
    KeyPair pair = generator.generateKeyPair();
    Key pubKey = pair.getPublic();
    Key privKey = pair.getPrivate();
    Socket s=new Socket("localhost",4321);
    DataOutputStream out=new DataOutputStream(s.getOutputStream());
    out.write(pubKey);
    s.close();
}
}

I got the following error:
C:\jdk1.6\bin>javac test4.java
test4.java:28: cannot find symbol
symbol : method write(java.security.Key)
location: class java.io.DataOutputStream
out.write(pubKey);
^
1 error
Please somebody help me