Socket Connections

I'm trying to do a project in which I do the transfer of a file. I am having problem at the time the server accepts the client connection. As I'm trying to do in different packages the class Talya initiates the connection of the server in line 21, but only after I start the client and there the error of java.null.

How do I open the server connection and accept on the client if they are in different classes?

code:

package servidor;
import java.io.BufferedInputStream;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;



@SuppressWarnings("unused")
public class Servidor {
    private ServerSocket socketServidor;
    private Socket socketConexao;
    private int porta;

    public Servidor(int porta) {
        this.porta = porta;
    }
    public void iniciaConexaoServidor() {

        try {
            this.socketServidor = new ServerSocket(this.porta);
        } catch (IOException e) {
            System.out.println("Não conseguiu iniciar o socket do servidor");
            e.printStackTrace();
        }
        try {
            this.socketConexao = socketServidor.accept();
        } catch (IOException e) {
            System.out.println("Não conseguiu aceitar a conexao com o cliente.");
            e.printStackTrace();
        }
    }
    public void enviarArquivo(String diretorio) throws Exception {
        File arquivo = new File(diretorio);
        FileInputStream fis = new FileInputStream(arquivo);
        BufferedInputStream bis = new BufferedInputStream(fis);
        OutputStream os = this.socketConexao.getOutputStream();

        byte[] conteudo;
        long fileLength = arquivo.length();
        long current = 0;

        while(current!=fileLength){ 
            int size = 10000;
            if(fileLength - current >= size)
                current += size;    
            else{
                size = (int)(fileLength - current); 
                current = fileLength;
            } 
            conteudo = new byte[size]; 
            bis.read(conteudo, 0, size); 
            os.write(conteudo);
            System.out.println("Mandando arquivo ... "+(current*100)/fileLength+"% completo!");
        }   

        os.flush(); 
        this.socketConexao.close();
        this.socketServidor.close();
        bis.close();
        System.out.println("Arquivo enviado com sucesso!");
    }
}

package Cliente;
import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;

public class Cliente {
    private Socket socketCliente;
    int porta;
    String address;
    public Cliente(int porta, String address) {
        this.porta=porta;
        this.address=address;
    }
    public void iniciarConexaoCliente() throws Exception {
        this.socketCliente = new Socket(address, porta);
    }
    public void transferenciaArquivo(String diretorio) throws IOException {
        byte[] conteudo = new byte[10000];

        FileOutputStream fos = new FileOutputStream(diretorio);
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        InputStream is = socketCliente.getInputStream();

        int bytesRead = 0;

        while((bytesRead=is.read(conteudo))!=-1) {
            bos.write(conteudo, 0, bytesRead);
        }
        bos.flush();
        socketCliente.close();

        System.out.println("Arquivo recebido!");
    }

}
import Cliente.Cliente;
import servidor.Servidor;

import java.io.IOException;
import java.util.Scanner;
@SuppressWarnings("unused")
public class Talya {

    public static void main(String[] args) {
        String adress; //192.168.25.9
        int porta;
        Scanner in = new Scanner(System.in);
        Scanner str = new Scanner(System.in);
        System.out.println("endereço ip: ");
        adress = str.nextLine();
        System.out.println("porta: ");
        porta = in.nextInt();

        Cliente cliente = new Cliente(porta, adress);
        Servidor servidor = new Servidor(porta);
        servidor.iniciaConexaoServidor();
        try {
            cliente.iniciarConexaoCliente();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String diretorioServidor = "C:\Users\ange4\eclipse-workspace\ProjetoComunicacao\TesteMusic.rar";
        try {
            servidor.enviarArquivo(diretorioServidor);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        String diretorioCliente = "C:\Users\ange4\eclipse-workspace\ProjetoComunicacao\TesteMusic2.rar";
        try {
            cliente.transferenciaArquivo(diretorioCliente);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }

}