DataOutputStream dOut = newDataOutputStream(socket.getOutputStream());

           byte[] s2 = Encrypt3.encrypt2(myString);

           dOut.writeInt(s2.length); // write length of the message
            dOut.write(s2);

import java.security.Key;

import javax.crypto.Cipher;

import javax.crypto.spec.SecretKeySpec;


public class Encrypt3 {
public static String key = "mykey";

public static byte[] encrypt2(String text ){
    String encrypt ="";

    try{
        // Create key and cipher
        Key aesKey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES");
        // encrypt the text
        cipher.init(Cipher.ENCRYPT_MODE, aesKey);
        byte[] encrypted = cipher.doFinal(text.getBytes());
        return encrypted ;
    }catch(Exception e){
        System.out.println(e);
    }
    return null ;
}


public static String decrypt2(byte[] encrypted2){
    String decrypt ="";
    try{
        Key aesKey = new SecretKeySpec(key.getBytes(), "AES");
        Cipher cipher = Cipher.getInstance("AES");
        // decrypt the text
        cipher.init(Cipher.DECRYPT_MODE, aesKey);
        decrypt = new String(cipher.doFinal(encrypted2));
    }catch(Exception e){
        System.out.println(e);
    }

    return decrypt ;
}