I have a little issue about a little thing I don't understand.
It's just a simple request: how do I display an xml I just got in a thread?
There is my method postData to get the xml, I make it display in a log.v as you can see below in the code, but I can't display it to a TextView out of the thread.
public class RecupXml_Activity extends Activity {
TextView campagne;
String user = "toto";
String password = "tata";
String theCampagneXml;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
campagne = (TextView) findViewById(R.id.campagneTest);
postData(user, password);
}
public void postData(final String login, final String password) {
Thread background = new Thread(new Runnable() {
URL url;
String buffer;
String theCampagneXml = null;
@Override
public void run() {
try {
URLConnection urlConnection;
String body = "login=" + URLEncoder.encode(login, "UTF-8") + "&password=" + URLEncoder.encode(password, "UTF-8");
url = new URL("http://3pi.tf/apps/sms/");
urlConnection = url.openConnection();
((HttpURLConnection) urlConnection).setRequestMethod("POST");
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.setUseCaches(false);
urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
urlConnection.setRequestProperty("Content-Length", "" + body.length());
OutputStreamWriter writer = null;
BufferedReader reader = null;
writer = new OutputStreamWriter(urlConnection.getOutputStream());
writer.write(body);
writer.flush();
reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
while ((buffer = reader.readLine()) != null) {
theCampagneXml = buffer;
}
Log.v("test", "xml = " + theCampagneXml);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
} catch (IOException e) {
// TODO Auto-generated catch block
}
campagne.post(new Runnable() {
@Override
public void run() {
campagne.setText("salut voici ta campagne : " + theCampagneXml);
}
});
}
});
background.start();
}
}
It appears in my Log but not in the TextView:/ I have a white empty Activity.
The problem is that you call postData() on UI-tread, meaning that the method also returns theCampagneXml on UI-thread, while your network operation goes on a worker thread. The following code with some changes and additions fixes the problem:
public class MainActivity extends Activity {
TextView campagne;
String user = "toto";
String password = "tata";
String theCampagneXml; // new
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
campagne = (TextView) findViewById(R.id.text);
postData(user, password); // new
}
public void postData(final String login, final String password) { // note: the return type has been changed
Thread background = new Thread(new Runnable() {
URL url;
String buffer;
String theCampagneXml = null; // new
@Override
public void run() {
try {
// no changes here but declaring `theCampagneXml` as class member
}
campagne.post(new Runnable() {
@Override
public void run() {
campagne.setText("hello, here is your XML : "+ theCampagneXml);
}
});
}
});
background.start();
}
}
Once the network operation is done and theCampagneXml is initialized, use post() for the TextView campagne that runs on UI-thread.
Additional info can be found in Processes and Threads.