When I call a webservice from a for loop to insert/update data into MySQL using PHP only the last item gets inserted/updated because (i think) the for loop completes quicker than the webservice, how can I delay my for loop or achieve a webservice call for each item returned in the for loop one after another.
For Loop Code:
for (int i = 0; i < lv.getCount(); i++) {
view = lv.getAdapter().getView(i, lv.getChildAt(i), lv);
if (view != null) {
// Getting my views
tvItem = (TextView) view.findViewById(R.id.tvItem);
strItem = tvItem.getText().toString();
//Call AsyncTask
accessWebService();
}
}
Webservice:
private class Webservice extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
}
return answer;
}
#Override
protected void onPostExecute(String result) {
try{
ld();
}catch (Exception e){
}
}
}// end async task
public void accessWebService() {
Webservice task = new Webservice();
//Update MySQL Using PHP
}
When you want to insert/update all data from for loop you must use callback like interfaces. Once you implement this it will wait for completing the process. Once completed it will call success or error method. Based on this you insert/update another record.
interface DataCallback {
fun onSuccess(result: Any)
fun onError(error: Any)
}
public void getCountries(new DataCallback(){
#Override
public void onSuccess(Object result){
// insert/update next record
}
#Override
public void onError(Object error){
// show error message
}
});
This is just example. You should convert it based on your need. Thanks.
Related
I want to receive and send data with a web server but the code does not work
What do I do for this code to work?
Note this code inside onCreate
try {
URL url = new URL("http://myweb.com/");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
InputStream Stream = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(Stream);
BufferedReader b = new BufferedReader(reader);
StringBuilder s = new StringBuilder();
String str ="";
while ((str = b.readLine())!=null) {
s.append(str);
}
String data = s.toString();
TextView myText = (TextView) findViewById(R.id.Text);
myText.setText(data);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Make sure that you do network-related tasks on a separate thread in Android. Also, check that you have the INTERNET permission set.
If you want to then update the UI from another thread, you have to use
runOnUiThread (new Runnable () {
public void run() {
//update ui in here
}
}
All your code runs in Main thread which should be always used for setting up the UI and to listen for UI events such as on click listeners.
Network calls are not allowed on this thread as they might take long time. Use AsyncTask API of android which is designed for running code in separate thread.
Create a class like one below for all GET request tasks.
public class DownloadTask extends AsyncTask<String, Void, Integer> {
private String TAG = "InDownloadTask";
private DownloadCallback callback;
private String data;
public DownloadTask(DownloadCallback cb){
callback = cb;
}
#Override
protected Integer doInBackground(String... params) {
Integer result = 0;
HttpURLConnection urlConnection;
try {
URL url = new URL(params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
int statusCode = urlConnection.getResponseCode();
if (statusCode == 200) {
BufferedReader r = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder response = new StringBuilder();
String line;
while ((line = r.readLine()) != null) {
response.append(line);
}
data = response.toString();
result = 1;
} else {
result = 0;
}
} catch (Exception e) {
Log.d(TAG, e.getLocalizedMessage());
}
return result;
}
#Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
callback.onFinishDownload(data, integer);
}
}
Create a callback interface that we use for the above class.
public interface DownloadCallback {
public void onFinishDownload(String data, Integer result);
}
Now from your activity onCreate
String url = "http://myweb.com/";
new DownloadTask(new DownloadCallback() {
public void onFinishDownload(String data, Integer result) {
if(result == 1)
myText.setText(data);
else
myText.setText("Error");
}
}).execute(url);
If you have many network related operations, use a Network library such as Volley which will take care of this.
I can't figure out how to get live updates in android from a json api that updates every 2-3 seconds. I've managed to download the JSON code and then create some arrays and log them, but I the values from the json api change every 2-3 seconds and I have no idea how to redownload the JSON. Thanks in advance for your help!
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DownloadTask task = new DownloadTask();
String result = null;
try{
result = task.execute("thelinkIuse").get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
public class DownloadTask extends AsyncTask<String, Void, String>{
#Override
protected String doInBackground(String... urls) {
String result = "";
URL url;
HttpURLConnection urlConnection = null;
while (true) {
try {
url = new URL(urls[0]);
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();
}
return result;
} catch (IOException e) {
e.printStackTrace();
return "Failed";
}
}
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try {
JSONArray arr = new JSONArray(result);
for (int i = 0; i < arr.length(); i++) {
JSONObject jsonPart = arr.getJSONObject(i);
symbols.add(jsonPart.getString("symbol"));
bids.add(jsonPart.getString("bid"));
asks.add(jsonPart.getString("ask"));
}
Log.i("Symbols", String.valueOf(symbols));
Log.i("Bids", String.valueOf(bids));
Log.i("Asks", String.valueOf(asks));
} catch (JSONException e) {
e.printStackTrace();
Log.i("failed", "failed");
}
}
}
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
try{
result =new DownloadTask().execute("thelinkIuse").get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
},0,5000);
This will call the asynctask every 5 seconds, thus fetching the updated JSON string
Im thinking you need some kind of polling mechanism. Look at Firebase Notifications because what you could do is have your server side code post an http request to the firebase server and that will trigger a server side push notification to your app in which you will have a receiver which will trigger the retrieval process
If you're absolutely sure about the updates occur every 2-3 seconds then you can periodically call the AsyncTask execute method. This is not considered a very good practice but can get your work done. Something on these lines:
private Timer autoRefresh;
autoRefresh=new Timer();
autoRefresh.schedule(new TimerTask() {
#Override
public void run() {
runOnUiThread(new Runnable() {
public void run() {
String result = null;
try{
result = task.execute("thelinkIuse").get();
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
});
}
}, 0, your_time_in_miliseconds);
The main problem is I'm unable to return two value help. i have tried lot of time but no success. And guys I'm new to this so please write your answer with respect to my code thanks in advance.
Here's my code
public class calculate extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... params) {
try {
uss = getJson("http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.xchange%20where%20pair%20in%20(%22INRUSD%22)&format=json&diagnostics=true&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback=");
JSONObject usjObj;
usjObj = new JSONObject(uss);
usResult = usjObj.getJSONObject("query").getJSONObject("results").getJSONObject("rate").getString("Rate");
eurr = getJson("http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.xchange%20where%20pair%20in%20(%22INREUR%22)&format=json&diagnostics=true&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback=");
JSONObject eurjObj;
eurjObj = new JSONObject(eurr);
eurResult = eurjObj.getJSONObject("query").getJSONObject("results").getJSONObject("rate").getString("Rate");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return eurResult + usResult;
////PROBLEM IS HERE ACTUALLY I DON'T KNOW HOW TO RETURN TWO OR MORE VALUE/////"
}
#Override
protected void onPostExecute(String usResult) {
valueus = Double.parseDouble(usResult);
inputus = lengthvalue * valueus;
us.setText("" + inputus);
valueeur = Double.parseDouble(eurResult);
inputeur = lengthvalue * valueeur;
eur.setText("" + inputeur);
}
}
public String getJson(String url) throws ClientProtocolException, IOException {
StringBuilder build = new StringBuilder();
HttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
HttpResponse response = client.execute(httpGet);
HttpEntity entity = response.getEntity();
InputStream content = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(content));
String con;
while ((con = reader.readLine()) != null) {
build.append(con);
}
return build.toString();
}
}
You should not try to cram everything into a String. There are better data structures to hold multiple values: array, Vector, List, etc. Declare your AsyntTask as:
public class calculate extends AsyncTask<String, String, String[]>
and then your doInBackgorund method would be something like this:
#Override
protected String doInBackground(String... params) {
String[] result = new String[numResults];
...
result[0] = usjObj.getJSONObject("query").getJSONObject("results").getJSONObject("rate").getString("Rate");
...
result[1] = usjObj.getJSONObject("query").getJSONObject("results").getJSONObject("rate").getString("Rate");
...
return result;
}
And finally your onPostExecute would be
#Override
protected void onPostExecute(String[] usResult) {
...
}
I have a method that need to update its status periodically to the server.
I am using AsyncTask to run the HTTP call in background.
PROBLEM: In onPostExecute method upon checking AsyncTask.getStatus, It show the previous task still running which is causing the error.
ERROR: java.lang.IllegalStateException: Cannot execute task: the task is already running.
DIFFERENT STRATEGIES USED TO SOLVE THE PROBLEM BUT NONE IS WORKING
1. Before Relaunching AsyncTask, checked the status, it is showing the thread is RUNNING.
2. Called the AsyncTask.cancel(true), immediately before calling the AsyncTask.execute if it is still running. It turns out AsyncTask still RUNNING and taking more than 3 mins to get cancel.
NOTE: I have checked many similar questions here, but haven't found helpful.
I would really appredicae if any one of you guys give me an example to solve this issue, Thanks a Million in advance......
public class MainActivity extends Activity implements AsyncResponse{
ConnectServer asyncTask =new ConnectServer();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
asyncTask.delegate = this;
setContentView(R.layout.activity_main);
//Start updating server using below method
loop();
}
public void processFinish(String output){
//this you will received result fired from async class of onPostExecute(result) method.
//Log.v(TAG, output);
if(output != null){
//not using this at this point
}
}
//Method that will call Async method to reach server
public void loop(){
TextView b = (TextView) findViewById(R.id.mField);
String str;
try {
str = asyncTask.execute(true).get();
b.setText(str);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// START SERVER CONNECTION
class ConnectServer extends AsyncTask<Boolean, String, String> {
public AsyncResponse delegate=null;
public int i = 0;
private Activity activity;
public void MyAsyncTask(Activity activity) {
this.activity = activity;
}
#Override
protected String doInBackground(Boolean... params) {
String result = null;
StringBuilder sb = new StringBuilder();
try {
// http post
HttpClient httpclient = new DefaultHttpClient();
HttpGet httppost = new HttpGet("http://192.168.0.21:8080");
HttpResponse response = httpclient.execute(httppost);
if (response.getStatusLine().getStatusCode() != 200) {
Log.d("GPSApp", "Server encountered an error");
}
BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF8"));
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
return result;
}
#Override
protected void onPostExecute(String result) {
TextView mField = (TextView) findViewById(R.id.mField);
mField.setText(result+i);
try {
Thread.sleep(10000);
//asyncTask =new ConnectServer();
i++;
String str = asyncTask.execute(true).get();
mField.setText(str+i);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ExecutionException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
protected void onPreExecute() {}
}
}
Call getStatus() to get the status of AsyncTask. If the status is AsyncTask.Status.RUNNING, cancel it.
I require a GET reequest from my own server to be extracted from the web and then displayed on screen with a TextView.
I have set up a GET Request.
public class GetMethodEx {
public String getInternetData() throws Exception{
BufferedReader in = null;
String data = null;
try
{
HttpClient client = new DefaultHttpClient();
URI website = new URI("http://www.mybringback.com");
HttpGet request = new HttpGet();
request.setURI(website);
HttpResponse response = client.execute(request);
in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer sb = new StringBuffer("");
String l = "";
String nl = System.getProperty("line.separator");
while ((l = in.readLine()) !=null){
sb.append(l + nl);
}
in.close();
data = sb.toString();
return data;
} finally{
if (in != null){
try{
in.close();
return data;
}catch (Exception e){
e.printStackTrace();
}
}
}
}
}
And I have set up on my main thread to extract the information and display it in a text view.
public class Home extends Activity {
TextView httpStuff;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.httpexample);
httpStuff = (TextView) findViewById(R.id.tvhttp);
GetMethodEx test = new GetMethodEx();
String returned;
try {
returned = test.getInternetData();
httpStuff.setText(returned);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
However, the Textview doesnt seem to change?
Can someone help me please.
Change your code using AsyncTask if you want to make any network operation from Ui Thread as:
public class Home extends Activity {
TextView httpStuff;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.httpexample);
httpStuff = (TextView) findViewById(R.id.tvhttp);
new LongOperation().execute("");
}
private class LongOperation extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
GetMethodEx test = new GetMethodEx();
String returned;
try {
returned = test.getInternetData();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return returned;
}
#Override
protected void onPostExecute(String result) {
// Update Ui here
httpStuff.setText(result);
}
}
}
Android OS > = 3.0
does not allow NetworkRequest on main UI thread.
Use AsyncTask to call webrequest.