Using AsyncTask, but experiencing unexpected behaviour
- by capcom
Please refer to the following code which continuously calls a new AsyncTask. The purpose of the AsyncTask is to make an HTTP request, and update the string result.
package room.temperature;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.concurrent.ExecutionException;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
public class RoomTemperatureActivity extends Activity {
String result = null;
StringBuilder sb=null;
TextView TemperatureText, DateText;
ArrayList<NameValuePair> nameValuePairs;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TemperatureText = (TextView) findViewById(R.id.temperature);
DateText = (TextView) findViewById(R.id.date);
nameValuePairs = new ArrayList<NameValuePair>();
for (int i = 0; i < 10; i++) {
RefreshValuesTask task = new RefreshValuesTask();
task.execute("");
}
}
// The definition of our task class
private class RefreshValuesTask extends AsyncTask<String, Integer, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected String doInBackground(String... params) {
InputStream is = null;
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://mywebsite.com/roomtemp/tempscript.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}
catch(Exception e) {
Log.e("log_tag", "Error in http connection" + e.toString());
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
sb.append(reader.readLine());
is.close();
result=sb.toString();
}
catch(Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
return result;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
//System.out.println(result);
setValues(result);
}
}
public void setValues(String resultValue) {
System.out.println(resultValue);
String[] values = resultValue.split("&");
TemperatureText.setText(values[0]);
DateText.setText(values[1]);
}
}
The problem I am experiencing relates to the AsyncTask in some way or the function setValues(), but I am not sure how. Essentially, I want each call to the AsyncTask to run, eventually in an infinite while loop, and update the TextView fields as I have attempted in setValues. I have tried since yesterday after asking a question which led to this code, for reference.
Oh yes, I did try using the AsyncTask get() method, but that didn't work either as I found out that it is actually a synchronous call, and renders the whole point of AsyncTask useless.
