I currently have multiple activity that needs to perform an asynctask for http post and I wish to make the asynctask as another class file so that the different activity can call the asynctask to perform the http post request and onPostExecute, call the method httpResult(result) in the activity that called the asynctask. I have tried to pass the activity in but I am unable to call the method in onPostExecute. How can I do that?
public class MyActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_MyActivity);
//logic here...
AsyncHttpPost asyncHttpPost = new AsyncHttpPost("someContent", this, dialog);
JSONObject data = new JSONObject();
data.put("key", "value");
try {
asyncHttpPost.execute(data);
}
catch (Exception ex){
ex.printStackTrace();
}
}
public static void httpResult(String result) {
//this method has to get called by asynctask to make changes to the UI
}
}
AsyncHttpPost.java
public class AsyncHttpPost extends AsyncTask<JSONObject, String, String> {
String recvdjson;
String mData="";
private ProgressDialog dialog;
private Activity activity;
public AsyncHttpPost(String data, Activity activity, ProgressDialog dialog) {
mData = data;
this.activity = activity;
this.dialog = dialog;
}
protected void onPreExecute()
{
dialog.show();
}
#Override
protected String doInBackground(JSONObject... params) {
//logic to do http request
return "someStringResult";
}
protected void onPostExecute(String result) {
dialog.dismiss();
activity.httpResult(result); //This line gives me error : The method httpResult(String) is undefined for the type Activity
}
}
Create an Interface called HttpResponseImpl in a seperate file and add the required method httpResult
interface HttpResponseImpl{
public void httpResult(String result);
}
Now implement this interface by you Activity class
public class MyActivity extends Activity implements HttpResponseImpl{
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_MyActivity);
//logic here...
AsyncHttpPost asyncHttpPost = new AsyncHttpPost("someContent", this, dialog);
JSONObject data = new JSONObject();
data.put("key", "value");
try {
asyncHttpPost.execute(data);
}
catch (Exception ex){
ex.printStackTrace();
}
}
public void httpResult(String result){
//this method has to get called by asynctask to make changes to the UI
}
}
And your AsyncHttpPost class would be.
public class AsyncHttpPost extends AsyncTask<JSONObject, String, String> {
String recvdjson;
String mData="";
private ProgressDialog dialog;
private HttpResponseImpl httpResponseImpl;
public AsyncHttpPost(String data, HttpResponseImpl httpResponseImpl, ProgressDialog dialog) {
mData = data;
this.httpResponseImpl = httpResponseImpl;
this.dialog = dialog;
}
protected void onPreExecute()
{
dialog.show();
}
#Override
protected String doInBackground(JSONObject... params) {
//logic to do http request
return "someStringResult";
}
protected void onPostExecute(String result) {
dialog.dismiss();
httpResponseImpl.httpResult(result);
}
}
Implements this HttpResponseImpl interface with all you Activity class from which you want to do HttpRequest.
Generic AsyncTask Example
Call it like
new RetrieveFeedTask(new OnTaskFinished()
{
#Override
public void onFeedRetrieved(String feeds)
{
//do whatever you want to do with the feeds
}
}).execute("http://enterurlhere.com");
RetrieveFeedTask.class
class RetrieveFeedTask extends AsyncTask<String, Void, String>
{
String HTML_response= "";
OnTaskFinished onOurTaskFinished;
public RetrieveFeedTask(OnTaskFinished onTaskFinished)
{
onOurTaskFinished = onTaskFinished;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
}
#Override
protected String doInBackground(String... urls)
{
try
{
URL url = new URL(urls[0]); // enter your url here which to download
URLConnection conn = url.openConnection();
// open the stream and put it into BufferedReader
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
while ((inputLine = br.readLine()) != null)
{
// System.out.println(inputLine);
HTML_response += inputLine;
}
br.close();
System.out.println("Done");
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
return HTML_response;
}
#Override
protected void onPostExecute(String feed)
{
onOurTaskFinished.onFeedRetrieved(feed);
}
}
OnTaskFinished.java
public interface OnTaskFinished
{
public void onFeedRetrieved(String feeds);
}
Related
I tried almost all the solution but there's some problem with my Inner AsyncTask class. It seems that doInBackground() is not being executed.
onPreExecute() and onPostExecute()are working. However, doInBackground() does not read the code.
I'm really sure about getJSON() is correct 100% because i used the same code before
this is my class
public class My extends Activity implements Runnable {
public static String s = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
findViewById(android.R.id.content).postDelayed(this, 3000);
getJSON("My link ");
}
#Override
public void run() {
startActivity(new Intent(SplashActivity.this, MainActivity.class));
finish();
}
}
AsyncTask:
private void getJSON(String url) {
class GetJSON extends AsyncTask<String, Void, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... params) {
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while((json = bufferedReader.readLine())!= null){
sb.append(json+"\n");
}
s = sb.toString().trim();
return sb.toString().trim();
} catch(Exception e){
return null;
}
}
#Override
protected void onPostExecute(String ss) {
super.onPostExecute(ss);
s = ss;
}
}
GetJSON gj = new GetJSON();
gj.execute(url);
}
Thanks
I have a mainactivity which extends SampleActivityBase with the following code
public class MainActivity extends SampleActivityBase {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
SlidingTabsBasicFragment fragment = new SlidingTabsBasicFragment();
transaction.replace(R.id.sample_content_fragment, fragment);
transaction.commit();
}
}
}
I have another class
public class SlidingTabsBasicFragment extends Fragment {
and within this class I have another sub class
class SamplePagerAdapter extends PagerAdapter {
after override all the necessary functions i have one more function
public String getJSON(String url) {
class GetJSON extends AsyncTask<String, Void, String> {
ProgressDialog loading;
#Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(SlidingTabsBasicFragment.this.getContext(), "Please Wait...", "Checking", true, true);
}
#Override
protected String doInBackground(String... params) {
Log.d("doInBackground : ", "Function Started");
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while ((json = bufferedReader.readLine()) != null) {
sb.append(json + "\n");
}
jsonString = sb.toString().trim();
return sb.toString().trim();
} catch (Exception e) {
return new String("Exception: " + e.getMessage());
}
}
#Override
protected void onPostExecute(String s) {
if(loading.isShowing()) {
loading.dismiss();
}
super.onPostExecute(s);
jsonString = s;
}
}
GetJSON gj = new GetJSON();
gj.execute(url);
return jsonString;
}
when I am calling this function in the SamplePagerAdapter class every thing work fine except Progress Dialog. it is not showing...
Please tell me what I am doing wrong and how can I show progress dialog. Tabs are showing data from online database, I want to start progress dialog when data is fatching.
Keep adapter class separate try .get() instaed of .execute
In the ProgressDialog initialization it is showing that LoginActivity.this is not an enclosing class.
In onPostExecute() method Toast is not getting executed and getApplicationContext() method cannot be resolved.
public class LoginActivity extends AppCompatActivity {
EditText et1,et2;
Button b;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login2);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
et1=(EditText)findViewById(R.id.editText5);
et2=(EditText)findViewById(R.id.editText6);
b=(Button)findViewById(R.id.button2);
}
public void login(View view)
{
new BackgroundTask().execute(et1.getText().toString(),et2.getText().toString());
Toast.makeText(this,"Button",Toast.LENGTH_LONG).show();
}
}
class Background extends AsyncTask<String, Integer, Integer>
{
ProgressDialog progressDialog=new ProgressDialog(LoginActivity.this);;
#Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog.setMessage("Processing");
progressDialog.setTitle("Title");
progressDialog.show();
}
int check_point =0;
String resp="";
#Override
protected Integer doInBackground(String... params) {
try {
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost("http://192.168.1.6/login.php");
HttpResponse response = client.execute(post);
InputStream in = response.getEntity().getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String s;
while ((s = reader.readLine()) != null) {
resp=resp+s;
}
}
catch (Exception e)
{
System.out.print(e);
}
return check_point;
}
#Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
progressDialog.dismiss();
Toast.makeText(getApplicationContext(),"ACtivity",Toast.LENGTH_LONG).show();
}
}
The class Background is not an inner class. Its outside of the scope of the LoginActivity.
Thats why you're getting that error. Try moving it as an inner class.
classs ParentClass{
//some fields, methods whatevenr
class InnerClass{
// this is inner
}
}
class OutSideScope{
// this is outside of the scope of the Parent Class
}
Happy coding ;)
I'm new to Android development and I'm trying to code a little app which allows me to grab an external JSON file and parse it. I got this to work, however it wont work if I try to execute it in the background as an AsyncTask. Eclipse gives me the error
The method findViewById(int) is undefined for the type LongOperation
in this line:
TextView txtView1 = (TextView)findViewById(R.id.TextView01);
Here is my code:
public class Main extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new LongOperation().execute();
}
}
class LongOperation extends AsyncTask<String, Void, String> {
private final Context LongOperation = null;
#Override
protected String doInBackground(String... params) {
try {
URL json = new URL("http://www.corps-marchia.de/jsontest.php");
URLConnection tc = json.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(tc.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
JSONArray ja = new JSONArray(line);
JSONObject jo = (JSONObject) ja.get(0);
TextView txtView1 = (TextView)findViewById(R.id.TextView01);
txtView1.setText(jo.getString("text") + " - " + jo.getString("secondtest"));
}
} catch (MalformedURLException e) {
Toast.makeText(this.LongOperation, "Malformed URL Exception: " + e, Toast.LENGTH_LONG).show();
} catch (IOException e) {
Toast.makeText(this.LongOperation, "IO Exception: " + e, Toast.LENGTH_LONG).show();
} catch (JSONException e) {
Toast.makeText(this.LongOperation, "JSON Exception: " + e, Toast.LENGTH_LONG).show();
}
return null;
}
#Override
protected void onPostExecute(String result) {
}
protected void onPreExecute() {
}
#Override
protected void onProgressUpdate(Void... values) {
ProgressDialog pd = new ProgressDialog(LongOperation);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setMessage("Working...");
pd.setIndeterminate(true);
pd.setCancelable(false);
}
}
Any ideas on how to fix this?
Here is what you should do to make it work as you want. Use onPostExecude()
public class Main extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new LongOperation(this).execute();
}
}
class LongOperation extends AsyncTask<String, Void, String> {
private Main longOperationContext = null;
public LongOperation(Main context) {
longOperationContext = context;
Log.v("LongOper", "Konstuktor");
}
#Override
protected String doInBackground(String... params) {
Log.v("doInBackground", "inside");
StringBuilder sb = new StringBuilder();
try {
URL json = new URL("http://www.corps-marchia.de/jsontest.php");
URLConnection tc = json.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(tc.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
JSONArray ja = new JSONArray(line);
JSONObject jo = (JSONObject) ja.get(0);
Log.v("line = ", "jo.getString() ="+jo.getString("text"));
sb.append(jo.getString("text") + " - " + jo.getString("secondtest")).append("\n");
}
} catch (MalformedURLException e) {
e.printStackTrace();
Log.v("Error", "URL exc");
} catch (IOException e) {
e.printStackTrace();
Log.v("ERROR", "IOEXECPTOIn");
} catch (JSONException e) {
e.printStackTrace();
Log.v("Error", "JsonException");
}
String result = sb.toString();
return result;
}
#Override
protected void onPostExecute(String result) {
Log.v("onPostExe", "result = "+result);
TextView txtView1 = (TextView)longOperationContext.findViewById(R.id.textView01);
txtView1.setText(result);
}
protected void onPreExecute() {
}
#Override
protected void onProgressUpdate(Void... values) {
ProgressDialog pd = new ProgressDialog(longOperationContext);
pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pd.setMessage("Working...");
pd.setIndeterminate(true);
pd.setCancelable(false);
}
}
The implementation of AsyncTask in one of the other answers is flawed. The progress dialog is being created every time within publishProgress, and the reference to the dialog is not visible outside the method. Here is my attempt:
public class Main extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
new LongOperation().execute();
}
class LongOperation extends AsyncTask<String, Void, String> {
ProgressDialog pd = null;
TextView tv = null;
#Override
protected void onPreExecute(){
tv = Main.this.findViewById(R.id.textvewid);
pd = new ProgressDialog(Main.this);
pd.setMessage("Working...");
// setup rest of progress dialog
}
#Override
protected String doInBackground(String... params) {
//perform existing background task
return result;
}
#Override
protected void onPostExecute(String result){
pd.dismiss();
tv.setText(result);
}
}
}
You are trying to do something which won't work. First of all you are inside of a class that extends AsyncTask so you won't have that method available as it is a method of the class Activity.
The second problem is that you are trying to do UI stuff in a method that is not synchronized with the UI thread. That is nothing you would want to do.
Process your JSON response in the doInBackground method and pass the result to the onPostExecute method where you will be able to handle UI stuff as it is synchronized with the UI thread.
The current setup you have will not make it easier for you to handle what you are trying to do anyway. You could make your LongOperation class a private class of your Activity class and define the TextView as a instance member. Grab it off the layout using findViewById inside of your OnCreate and modify (set text or whatever) inside the onPostExecute method of your AsyncTask.
I hope it is somewhat clear what I meant.
findViewById is method in Activity class. You should pass instance of your activity to your LongOperation when you create it. Then use that instance to call findViewById.
I believe I'm doing this correctly, in my activity class I'm calling execute the alert dialog appears and then the data load but the alert dialog never goes away. Here is my AsyncTask code:
Followed by my activity code.
public class Worker extends AsyncTask<URL, Integer, Long>{
private Activity ne;
private ProgressDialog progressDialog;
private Handler handler;
public Worker(Handler handler, Activity ne){
this.handler = handler;
this.ne = ne;
}
protected void onPreExecute() {
progressDialog = ProgressDialog.show(ne,"", "Retrieving News Events", true);
}
protected void onProgressUpdate(Void... progress) {
}
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
/* (non-Javadoc)
* #see android.os.AsyncTask#doInBackground(Params[])
*/
#Override
protected Long doInBackground(URL... urls) {
HttpClient client = new DefaultHttpClient();
HttpGet get;
try {
get = new HttpGet(urls[0].toURI());
ResponseHandler<String> response = new BasicResponseHandler();
String responseBody = client.execute(get, response);
String page = responseBody;
Bundle data = new Bundle();
data.putString("page",page);
Message msg = new Message();
msg.setData(data);
handler.sendMessage(msg);
}
catch (Throwable t) {
Log.d("UpdateNews", "PROBLEMS");
}
return null;
}
}
public class NewsEvents extends ListActivity{
private URL JSONNewsEvents;
private ArrayList<NewsEvent> neList;
private ArrayList<String> keyWordList;
private Worker worker;
private TextView selection;
private ProgressDialog progressDialog;
static final int PROGRESS_DIALOG = 0;
public static final String KEYWORDS = "keywords";
private NewsEvents ne;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newsevents);
ne = this;
neList = new ArrayList<NewsEvent>();
selection=(TextView)findViewById(R.id.selection);
try {
JSONNewsEvents = new URL(getString(R.string.jsonnewsevents));
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
worker = new Worker(handler, this);
setListAdapter(new IconicAdapter());
getKeywords();
worker.execute(JSONNewsEvents);
}
/**
* #return
*/
public ArrayList<String> getKeywords(){
try {
InputStream fi = openFileInput(KEYWORDS);
if (fi!=null) {
ObjectInputStream in = new ObjectInputStream(fi);
keyWordList = (ArrayList<String>) in.readObject();
in.close();
}
}
catch (java.io.FileNotFoundException e) {
// that's OK, we probably haven't created it yet
}
catch (Throwable t) {
Toast
.makeText(this, "Exception: "+t.toString(), Toast.LENGTH_LONG)
.show();
}
if(keyWordList == null){
keyWordList = new ArrayList<String>();
return keyWordList;
}
return keyWordList;
}
public void onListItemClick(ListView parent, View v,
int position, long id) {
startFullNewsEvent(neList.get(position));
}
/**
* #param newsEvent
*/
public void startFullNewsEvent(NewsEvent ne) {
Intent intent = new Intent(this, FullNewsEvent.class);
intent.putExtra("ne", ne);
this.startActivity(intent);
finish();
}
private Handler handler = new Handler(){
#Override
public void handleMessage(Message msg) {
String page = msg.getData().getString("page");
try {
JSONArray parseArray = new JSONArray(page);
for (int i = 0; i < parseArray.length(); i++) {
JSONObject jo = parseArray.getJSONObject(i);
String title = jo.getString("title");
String body =jo.getString("body");
String pd = jo.getString("postDate");
String id = jo.getString("id");
NewsEvent ne = new NewsEvent(title, pd , body, id);
boolean unique = true;
for(NewsEvent ne0 : neList){
if(ne.getId().equals(ne0.getId())){
unique = false;
}else{
unique = true;
}
}
if(unique == true){
neList.add(ne);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
ne.setListAdapter(new IconicAdapter());
}
};
public class IconicAdapter extends ArrayAdapter<NewsEvent> {
IconicAdapter() {
super(NewsEvents.this, R.layout.rownews, neList);
}
public View getView(int position, View convertView,ViewGroup parent) {
LayoutInflater inflater=getLayoutInflater();
View row=inflater.inflate(R.layout.rownews, parent, false);
TextView label=(TextView)row.findViewById(R.id.label);
ImageView image= (ImageView)row.findViewById(R.id.icon);
String body = neList.get(position).getBody();
body.replaceAll("\\<.*?>", "");
String title = neList.get(position).getTitle();
for(String s : keyWordList){
if(body.contains(s) || body.contains(s.toLowerCase()) ||
title.contains(s) || title.contains(s.toLowerCase())){
neList.get(position).setInterested(true);
}
}
if(neList.get(position).isInterested() == true){
image.setImageResource(R.drawable.star);
}
label.setText(neList.get(position).getTitle());
return(row);
}
}
}
First of all change your onPostExecute to include the #Override:
#Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
In your class definition include this:
public class Worker extends AsyncTask<Void, Void, Void>
The first parameter is the type of input to the doInBackground method, the second is the type of the input to the onProgressUpdate and the third is the type of the input to the onPostExecute and the result from doInBackground.
It does not look like you are using the input parameter to the doInBackground method, so just change that to Void... and change the return type as well:
protected Void doInBackground(Void... paramArrayOfParams) { ... }
Does this help?
Edit:
I saw you had changed your code to use the parameter of the doInBackground, so the first parameter in your class definition is correct. However, try putting Void as the two last parameters. And change the return type of the doInBackground to Void too.
Like this:
public class Worker extends AsyncTask<URL, Void, Void>{
private Activity ne;
private ProgressDialog progressDialog;
private Handler handler;
public Worker(Handler handler, Activity ne){
this.handler = handler;
this.ne = ne;
}
#Override
protected void onPreExecute() {
progressDialog = ProgressDialog.show(ne,"", "Retrieving News Events", true);
}
protected void onProgressUpdate(Void... progress) {
}
#Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
/* (non-Javadoc)
* #see android.os.AsyncTask#doInBackground(Params[])
*/
#Override
protected Void doInBackground(URL... urls) {
HttpClient client = new DefaultHttpClient();
HttpGet get;
try {
get = new HttpGet(urls[0].toURI());
ResponseHandler<String> response = new BasicResponseHandler();
String responseBody = client.execute(get, response);
String page = responseBody;
Bundle data = new Bundle();
data.putString("page",page);
Message msg = new Message();
msg.setData(data);
handler.sendMessage(msg);
}
catch (Throwable t) {
Log.d("UpdateNews", "PROBLEMS");
}
return null;
}
You're not overriding the asynctask method correctly. Take a look at an example
http://developer.android.com/reference/android/os/AsyncTask.html
and note now they declare their asynctask
extends AsyncTask<URL, Integer, Long>