public class MainActivity extends AppCompatActivity
{
public List<CharSequence> chat = new ArrayList<CharSequence>();

private void connect(final String ip, final int port) {

        Thread thread = new Thread(new Runnable() {
@Override
public void run() {

try {
InetAddress addr = InetAddress.getByName(ip);
SocketAddress sockaddr = new InetSocketAddress(addr.getHostAddress(), port);

                                         catch (Exception e) {
if(tabLayout.getSelectedTabPosition() == 0){
chat.add(Html.fromHtml("<br><font color='red'>" + getString(R.string.coneccionFallida) + "</font>")); //Cuando cambio de pestaña, el texto no es mostrado en el EditText
}
else{
try{

runOnUiThread(new Runnable() {

@Override
public void run() {
secondFragment.chat.append(Html.fromHtml("<br><font color='red'>" + getString(R.string.coneccionFallida) + "</font>")); //funciona bien
}
});
}
catch(Exception e2){

}
}
}
}
});

        thread.start();
}
}

EditText chat;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.chat, container, false);
chat = (EditText) view.findViewById(R.id.chatEditText1);
if(!((MainActivity) getActivity()).chat.isEmpty()){
appenText(((MainActivity) getActivity()).chat);
((MainActivity) getActivity()).chat.clear();
}
return view;
}

public void appenText(List<CharSequence> l){
for(int f=0; f<l.size(); f++){
chat.append(l.get(f)); //Agrega Strings pero no objetos de tipo Spanned
}
}

public static byte[] Decompress(byte[] data) throws IOException
{
try (InputStream ms = new ByteArrayInputStream(data);
InflaterInputStream s = new InflaterInputStream(ms);
ByteArrayOutputStream baos = new ByteArrayOutputStream();) {
byte[] buf = new byte[8192];
for (int r = s.read(buf); r != -1; r = s.read(buf))
baos.write(buf, 0, r);
return baos.toByteArray();
}
}