Q:

CalledFromWrongThreadException when updating TextView through API

I'm working with an API. When I click the button in my app, it calls a synchronized void that requests data from the application. The data is then returned by CReceiver in the implemented method userInfo where I append the returned data to a TextView. I can System.out.println the information in userInfo and it works but if I try to append the TextView, I get a CalledFromWrongThreadException. What is the proper way to update the TextView with this information?
MainActivity
    public class MainActivity extends Activity implements CReceiver {
       private CSocket c_client = new CSocket(this);
       private TextView textLog;

       @Override
       protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            Button btnReqUser = (Button) findViewById(R.id.btnReqUser);

            textLog = (TextView) findViewById(R.id.textLog);

            btnReqUser.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View v) {
                    c_client.reqUser("roger");
                }
            });
       }

       @Override
       public void userInfo(String firstName, String lastName, String address, String phone) {
       // TODO Auto-generated method stub
       textLog.append(firstName + " " + lastName + " " + address + " " + phone);    
       }
    }

CSocket
    public synchronized void reqUser(String userName) {
    ...
    }

A:

What is the proper way to update the TextView with this information?

Since this is an Activity, use runOnUiThread():
@Override
   public void userInfo(String firstName, String lastName, String address, String phone) {
   runOnUiThread(new Runnable() {
     public void run() {
       // do something here with your TextView
     }
   });
}

