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
		}
	}