Properly Using AsyncTask get() - android

I am running into a problem. I need to use asynctask to retrieve JSON data and I need that data before I moved to the next part of the program. However, when using the get() method of AsyncTask I have 5 to 8 sec black screen before I see the data is displayed. I would like to display a progress dialog during the data retrieval but I cannot do this due to the black screen. Is there a way to put into another thread? here is some code
AsyncTask
public class DataResponse extends AsyncTask<String, Integer, Data> {
AdverData delegate;
Data datas= new Data();
Reader reader;
Context myContext;
ProgressDialog dialog;
String temp1;
public DataResponse(Context appcontext) {
myContext=appcontext;
}
#Override
protected void onPreExecute()
{
dialog= new ProgressDialog(myContext);
dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
dialog.setCancelable(false);
dialog.setMessage("Retrieving...");
dialog.show();
};
#Override
protected Data doInBackground(String... params) {
temp1=params[0];
try
{
InputStream source = retrieveStream(temp1);
reader = new InputStreamReader(source);
}
catch (Exception e)
{
e.printStackTrace();
}
Gson gson= new Gson();
datas= gson.fromJson(reader, Data.class);
return datas;
}
#Override
protected void onPostExecute(Data data)
{
if(dialog.isShowing())
{
dialog.dismiss();
}
}
private InputStream retrieveStream(String url) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet getRequest = new HttpGet(url);
try {
HttpResponse getResponse = client.execute(getRequest);
final int statusCode = getResponse.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w(getClass().getSimpleName(),
"Error " + statusCode + " for URL " + url);
return null;
}
HttpEntity getResponseEntity = getResponse.getEntity();
return getResponseEntity.getContent();
}
catch (IOException e) {
getRequest.abort();
Log.w(getClass().getSimpleName(), "Error for URL " + url, e);
}
return null;
}
}
DisplayInfo
public class DisplayInfo extends Activity implements AdverData {
public static Data data;
public ProjectedData attup;
public ProjectedData attdown;
public ProjectedData sprintup;
public ProjectedData sprintdown;
public ProjectedData verizionup;
public ProjectedData veriziondown;
public ProjectedData tmobileup;
public ProjectedData tmobiledown;
public ProjectedAll transfer;
private ProgressDialog dialog;
public DataResponse dataR;
Intent myIntent; // gets the previously created intent
double x; // will return "x"
double y; // will return "y"
int spatial; // will return "spatial"
//public static Context appContext;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
StrictMode.ThreadPolicy policy = new StrictMode.
ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
dialog= new ProgressDialog(DisplayInfo.this);
dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
dialog.setCancelable(false);
dialog.setMessage("Retrieving...");
dialog.show();
myIntent= getIntent(); // gets the previously created intent
x = myIntent.getDoubleExtra("x",0); // will return "x"
y = myIntent.getDoubleExtra("y", 0); // will return "y"
spatial= myIntent.getIntExtra("spatial", 0); // will return "spatial"
String URL = "Some URL"
dataR=new DataResponse().execute(attUp).get();
#Override
public void onStart()
{more code}

When you are using get, using Async Task doesn't make any sense. Because get() will block the UI Thread, Thats why are facing 3 to 5 secs of blank screen as you have mentioned above.
Don't use get() instead use AsyncTask with Call Back check this AsyncTask with callback interface

Related

How to use Handler in AsynkTask in android

I am fetching data from server using AsynkTask which works fine but I want to use handler in AsynkTask to reduce load from main Thread.How can I use Handler in AsynkTask. Kindly help me to solve this problem.
Here is my code.
public class CLoginScreen extends Fragment {
public static String s_szLoginUrl = "http://192.168.0.999:8080/rest/json/metallica/getLoginInJSON";
public static String s_szresult = " ";
public static String s_szMobileNumber, s_szPassword;
public static String s_szResponseMobile, s_szResponsePassword;
public View m_Main;
public EditText m_InputMobile, m_InputPassword;
public AppCompatButton m_LoginBtn, m_ChangePass, m_RegisterBtn;
public CJsonsResponse m_oJsonsResponse;
public boolean isFirstLogin;
public JSONObject m_oResponseobject;
public LinearLayout m_MainLayout;
public CLoginSessionManagement m_oLoginSession;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
m_Main = inflater.inflate(R.layout.login_screen, container, false);
((AppCompatActivity) getActivity()).getSupportActionBar().hide();
m_oLoginSession = new CLoginSessionManagement(getActivity());
init();
return m_Main;
}
public void init() {
m_MainLayout = (LinearLayout) m_Main.findViewById(R.id.mainLayout);
m_InputMobile = (EditText) m_Main.findViewById(R.id.input_mobile);
m_InputPassword = (EditText) m_Main.findViewById(R.id.input_password);
m_LoginBtn = (AppCompatButton) m_Main.findViewById(R.id.btn_Login);
m_ChangePass = (AppCompatButton) m_Main.findViewById(R.id.btn_ChangePass);
m_ChangePass.setBackgroundColor(Color.TRANSPARENT);
m_ChangePass.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CChangePasswordScreen()).commit();
}
});
m_RegisterBtn = (AppCompatButton) m_Main.findViewById(R.id.btn_Register);
m_RegisterBtn.setBackgroundColor(Color.TRANSPARENT);
m_RegisterBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CRegistrationScreen()).commit();
}
});
m_LoginBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
new LoginAttempt().execute();
}
});
}
private class LoginAttempt extends AsyncTask<String, Void, String> {
public Dialog m_Dialog;
public ProgressBar m_ProgressBar;
#Override
protected void onPreExecute() {
super.onPreExecute();
m_Dialog = new Dialog(getActivity());
m_Dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
m_Dialog.setContentView(R.layout.progress_bar);
showProgress("Please wait while Logging...");// showing progress ..........
}
#Override
protected String doInBackground(String... params) {
getLoginDetails();// getting login details from editText...........
InputStream inputStream = null;
m_oJsonsResponse = new CJsonsResponse();
isFirstLogin = true;
try {
// 1. create HttpClient
HttpClient httpclient = new DefaultHttpClient();
// 2. make POST request to the given URL
HttpPost httpPost = new HttpPost(s_szLoginUrl);
String json = "";
// 3. build jsonObject
JSONObject jsonObject = new JSONObject();
jsonObject.put("agentCode", s_szMobileNumber);
jsonObject.put("pin", s_szPassword);
jsonObject.put("firstloginflag", m_oLoginSession.isLogin());
// 4. convert JSONObject to JSON to String
json = jsonObject.toString();
// 5. set json to StringEntity
StringEntity se = new StringEntity(json);
// 6. set httpPost Entity
httpPost.setEntity(se);
// 7. Set some headers to inform server about the type of the content
// httpPost.setHeader("Accept", "application/json"); ///not required
httpPost.setHeader("Content-type", "application/json");
// 8. Execute POST request to the given URL
HttpResponse httpResponse = httpclient.execute(httpPost);
HttpEntity entity = httpResponse.getEntity();
// 9. receive response as inputStream
inputStream = entity.getContent();
System.out.print("InputStream...." + inputStream.toString());
System.out.print("Response...." + httpResponse.toString());
StatusLine statusLine = httpResponse.getStatusLine();
System.out.print("statusLine......" + statusLine.toString());
////Log.d("resp_body", resp_body.toString());
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) {
// 10. convert inputstream to string
if (inputStream != null) {
s_szresult = m_oJsonsResponse.convertInputStreamToString(inputStream);
//String resp_body =
EntityUtils.toString(httpResponse.getEntity());
}
} else
s_szresult = "Did not work!";
} catch (Exception e) {
Log.d("InputStream", e.getLocalizedMessage());
}
System.out.println("s_szResult....." + s_szresult);
System.out.println("password......" + s_szPassword);
// 11. return s_szResult
return s_szresult;
}
#Override
protected void onPostExecute(String response) {
super.onPostExecute(response);
hideProgress();// hide progressbar after getting response from server......
try {
m_oResponseobject = new JSONObject(response);// getting response from server
new Thread() {// making child thread...
public void run() {
Looper.prepare();
try {
getResponse();// getting response from server
Looper.loop();
} catch (JSONException e) {
e.printStackTrace();
}
}
}.start();
} catch (JSONException e) {
e.printStackTrace();
}
}
public void getResponse() throws JSONException {
if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Transaction Successful")) {
m_oLoginSession.setLoginData(s_szResponseMobile, s_szResponsePassword);
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.container, new CDealMainListing()).commit();
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Agentcode Can Not Be Empty")) {
showToast("Please Enter Valid Mobile Number");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Pin Can Not Be Empty")) {
showToast("Please Enter Password");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Invalid PIN")) {
showToast("Invalid Password");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Subscriber/Agent Blocked due to Wrong Attempts")) {
showToast("You are blocked as You finished you all attempt");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Connection Not Available")) {
showToast("Connection Lost ! Please Try Again");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("Subscriber/Agent Not Found")) {
showToast("User not found ! Kindly Regiter before Login");
} else if (m_oResponseobject.getString("resultdescription").equalsIgnoreCase("OTP not verify")) {
showToast("Otp not Verify ! Kindly Generate Otp on Sign Up");
}
}
public void showToast(String message) {// method foe showing taost message
Toast toast = Toast.makeText(getActivity(), "" + message, Toast.LENGTH_SHORT);
toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();
}
public void getLoginDetails() {
s_szMobileNumber = m_InputMobile.getText().toString();
s_szPassword = m_InputPassword.getText().toString();
}
public void showProgress(String message) {
m_ProgressBar = (ProgressBar) m_Dialog.findViewById(R.id.progress_bar);
TextView progressText = (TextView) m_Dialog.findViewById(R.id.progress_text);
progressText.setText("" + message);
progressText.setVisibility(View.VISIBLE);
m_ProgressBar.setVisibility(View.VISIBLE);
m_ProgressBar.setIndeterminate(true);
m_Dialog.setCancelable(false);
m_Dialog.setCanceledOnTouchOutside(false);
m_Dialog.show();
}
public void hideProgress() {
m_Dialog.dismiss();
}
}
}
As per android docs here
An asynchronous task is defined by a computation that runs on a
background thread and whose result is published on the UI thread.
And loading data from URL with Handler is not a good thing. Instead use Executor or ThreadPoolExecutor to do heavy background tasks.
You Can Use
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
getResponse();
}
});
you can do like this:
class MyAsyncTask extends AsyncTask<Object,Object,Object>{
Private Context c;
private Handler handler;
private final static int YOUR_WORK_ID = 0x11;
public MyAsyncTask(Context c,Handler handler){
this.c = c;
this.handler = handler;
}
protected Object doInBackground(Object... params){
//do your work
...
Message m = handler.obtainMessage();
m.what = YOUR_WORK_ID;
...
handler.sendMessage().sendToTarget();
}
}
And in your fragment ,you can init a handler as params to MyAsyncTask,and deal with you work in handleMessage();

How can I get filleUploaded URL as string from async task in android

I am uploading an image on server by using async task and in the end I want to return value of uploaded file url. How can I do that
I am calling asynctask as
new Config.UploadFileToServer(loginUserInfoId, uploadedFileURL).execute();
and my asynctask function is as:
public static final class UploadFileToServer extends AsyncTask<Void, Integer, String> {
String loginUserInfoId = "";
String filePath = "";
long totalSize = 0;
public UploadFileToServer(String userInfoId, String url){
loginUserInfoId = userInfoId;
filePath = url;
}
#Override
protected void onPreExecute() {
// setting progress bar to zero
super.onPreExecute();
}
#Override
protected void onProgressUpdate(Integer... progress) {
// Making progress bar visible
// updating progress bar value
}
#Override
protected String doInBackground(Void... params) {
return uploadFile();
}
#SuppressWarnings("deprecation")
private String uploadFile() {
String responseString = null;
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(Config.HOST_NAME + "/AndroidApp/AddMessageFile/"+loginUserInfoId);
try {
AndroidMultiPartEntity entity = new AndroidMultiPartEntity(
new AndroidMultiPartEntity.ProgressListener() {
#Override
public void transferred(long num) {
publishProgress((int) ((num / (float) totalSize) * 100));
}
});
File sourceFile = new File(filePath);
// Adding file data to http body
entity.addPart("file", new FileBody(sourceFile));
totalSize = entity.getContentLength();
httppost.setEntity(entity);
// Making server call
HttpResponse response = httpclient.execute(httppost);
HttpEntity r_entity = response.getEntity();
int statusCode = response.getStatusLine().getStatusCode();
if (statusCode == 200) {
// Server response
responseString = EntityUtils.toString(r_entity);
} else {
responseString = "Error occurred! Http Status Code: "
+ statusCode;
}
} catch (ClientProtocolException e) {
responseString = e.toString();
} catch (IOException e) {
responseString = e.toString();
}
responseString = responseString.replace("\"","");
return responseString;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
}
}
Try my code as given below.
public Result CallServer(String params)
{
try
{
MainAynscTask task = new MainAynscTask();
task.execute(params);
Result aResultM = task.get(); //Add this
}
catch(Exception ex)
{
ex.printStackTrace();
}
return aResultM;//Need to get back the result
}
You've almost got it, you should do only one step. As I can see, you are returning the result at the doInBackground method (as a result of calling uploadFile). Now, this value is passed to the onPostExecute method, which is executed on the main thread. In its body you should notify components, which are waiting for result, that result is arrived. There are a lot of methods to do it, but if you don't want to used 3rd party libs, the simplest one should be to inject listener at the AsyncTask constructor and call it at the onPostExecute. For example, you can declare the following interface:
public interface MyListener {
void onDataArrived(String data);
}
And inject an instance implementing it at the AsyncTask constructor:
public UploadFileToServer(String userInfoId, String url, MyListener listener){
loginUserInfoId = userInfoId;
filePath = url;
mListener = listener;
}
Now, you can simply use it at the onPostExecute:
#Override
protected void onPostExecute(String result) {
listener.onDataArrived(result);
super.onPostExecute(result); //actually `onPostExecute` in base class does nothing, so this line can be removed safely
}
If you are looking for a more complex solutions, you can start from reading this article.

Android: ProgressDialog in external async class (sth block async thread)

I have main activity:
public class ChooseWriteSentenceActivity extends ActionBarActivity{
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String userName = "Zdzisiu";
String password = "Ziemniak";
MainServie service = new MainService(this);
boolean isExsist = service.findUser(String userName, String password);
//more code...
}
}
In my app service uses repositories and jsonconsumers but for simpler code I'm skipping them.
public class MyService{
private Context context;
public MyService(Context context){
this.context = context
}
public boolean findUser(String userName, String password){
String resultS = null;
try{
resultS = new QueryExecutorFindUser(context).execute(userName,password).get();
}
catch(Exception ex){
ex.printStackTrace();
}
boolean realRes = jsonConsumer(resultS).getFindUser();
return realRes;
}
}
public class QueryExecutorFindUser extends AsyncTask<String,Void,String> {
protected final String connectionUrl = "http://myWebService:44302/Service.svc/";
protected ProgressDialog progressDialog;
protected Context curContext;
public QueryExecutor(Context context){
curContext = context;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
progressDialog = ProgressDialog.show(curContext,"Loading...",
"Loading application View, please wait...", false, false);
}
#Override
protected void onPostExecute(String result)
{
super.onPostExecute(result);
progressDialog.dismiss();
}
protected String doInBackground(String... args){
String result = null;
String url = connectionUrl + args[0] + "/" + args[1];
HttpResponse response = null;
HttpClient httpclient = this.getNewHttpClient();
HttpGet get = new HttpGet(url);
get.setHeader("Accept", "application/json");
get.setHeader("Content-type", "application/json");
try{
response = httpclient.execute(get);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpStatus.SC_OK){
if(response != null){
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
result = out.toString();
}
} else{
throw new IOException(statusLine.getReasonPhrase());
}
} catch(Exception ex){
ex.getMessage();
} finally{
if(response != null){
try{
response.getEntity().getContent().close();
} catch(Exception ex){
}
}
}
return result;
}
}
And progress dialog is show but only after all code in onCreatre in ChooseWriteSentenceActivity including doInBacground(...) from QueryExecutor is finished (so it disappears practically at the same time). It looks like sth waiting for thread with QueryExecutorFindUser.doInBackground() and it is runs like synchronously (?), I think that because when I debug code onPreExecute() is running correctly (and start before doInBackground(...)) and progressDialog.isShowing() == true (but not on the screen :( ).
If I remove extends AsyncTask from QueryExecutorFindUser and make private class with this extension in main activity (and run all code from onCreated() including service.findUser() in thisPrivateClass.doInBackground(...)) it works okey.
I prefer to have progressDialog in one place no in all main activities (of cource in practise I use QueryExecutor for all queries not only findUser) but I don't have idea what i am doing wrong. I spent all day on it with no result :(
Dialogs are tied to an Activity and ultimately must be hosted by one. So until your app's activity gets created, the dialog will not display.

Load Images Into ImageAdapter through JSON

HI I was trying GridView demo form this link
and it work superb but now I want to get the Images for server database.For that I implemented the handler class which will pass my URL and get the response from server. In response the JSON will contains the URLs of images. I also implemented one method which will download the images form that resultant URLs and set them into the Bitmap array..
The Service Handler class work correct but I don't know the changes I made in ImageAdapter class are correct or not..Please tell me where I'm getting wrong..
Following is code for ImageAdapter class..
public class ImageAdapter extends BaseAdapter {
private Context mContext;
Bitmap bm[]=new Bitmap[8];
ImageAdapter img;
public String[] imageurls=null;
// Keep all Images in array
public Integer[] mThumbIds ={
R.drawable.pic_1, R.drawable.pic_2,
R.drawable.pic_3, R.drawable.pic_4,
};
// Constructor
public ImageAdapter(Context c){
mContext = c;
img =new ImageAdapter(mContext);
new GetImageUrls(mContext).execute();
}
#Override
public int getCount() {
return mThumbIds.length;
}
#Override
public Object getItem(int position) {
return mThumbIds[position];
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView = new ImageView(mContext);
if(bm[position]==null)
imageView.setImageResource(mThumbIds[position]);
else
imageView.setImageBitmap(bm[position]);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(new GridView.LayoutParams(70, 70));
return imageView;
}
public class GetImageUrls extends AsyncTask<Void, Void, Void>
{
Context context;
private ProgressDialog pDialog;
// URL to get JSON
private static final String url= "http://192.xxx.x.xxx/Demo_Folder/test.json";
private static final String RESULT = "mainCategory";
private static final String URLS = "mcatimage";
// JSONArray
JSONArray loginjsonarray=null;
//result from url
//public String[] imageurls=null;
public GetImageUrls(Context c) {
this.context=c;
}
protected void onPreExecute() {
// Showing progress dialog
pDialog = new ProgressDialog(context);
pDialog.setMessage("Loading...");
pDialog.setCancelable(false);
//pDialog.show();
}
protected Void doInBackground(Void... arg) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonstr = sh.makeServiceCall(url, ServiceHandler.GET, null);
Log.d("Response: ", ">"+jsonstr);
if(jsonstr!=null){
try {
JSONObject jsonObj =new JSONObject(jsonstr);
loginjsonarray=jsonObj.getJSONArray(RESULT);
for(int i=0;i<loginjsonarray.length();i++){
JSONObject l=loginjsonarray.getJSONObject(i);
imageurls[i]=l.getString(URLS);
}
} catch (JSONException e) {
e.printStackTrace();
}
}else{
Toast.makeText(context,"Check your Internet Connection",Toast.LENGTH_SHORT).show();
}
return null;
}
protected void onPostExecute(Integer result) {
// Dismiss the progress dialog
if(pDialog.isShowing()){
pDialog.dismiss();
new ImageDownloader().execute();
}
}
}
private class ImageDownloader extends AsyncTask<Integer, Integer, String>
{
Context context;
private ProgressDialog pDialog;
#Override
public void onPreExecute()
{
// Showing progress dialog
pDialog = new ProgressDialog(context);
pDialog.setMessage("Loading...");
pDialog.setCancelable(false);
//pDialog.show();
}
protected void onPostExecute(String result)
{
pDialog.hide();
}
protected void onProgressUpdate(Integer... progress) {
img.notifyDataSetChanged();
}
protected String doInBackground(Integer... a)
{
for(int i=0;i<4;i++)
{
bm[i]=downloadBitmap(imageurls[i]);
this.publishProgress(i);
}
return "";
}
}
Bitmap downloadBitmap(String url) {
final HttpClient client = new DefaultHttpClient();
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode + " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
// Could provide a more explicit error message for IOException or IllegalStateException
getRequest.abort();
Log.e("ImageDownloader", "Error while retrieving bitmap from " + url);
} finally {
if (client != null) {
//client.
}
}
return null;
}
}
As I run the code it get stop immediately..and gives the error like
FATAL EXCEPTION: main
Process: com.example.androidhive, PID: 1383
java.lang.StackOverflowError
at java.util.AbstractList.<init>(AbstractList.java:376)
at java.util.ArrayList.<init>(ArrayList.java:81)
at android.database.Observable.<init>(Observable.java:34)
at android.database.DataSetObservable.<init>(DataSetObservable.java:24)
at android.widget.BaseAdapter.<init>(BaseAdapter.java:31)
at com.example.androidhive.ImageAdapter.<init>(ImageAdapter.java:40)
remove this line
img =new ImageAdapter(mContext);
from Constructor of ImageAdapter. It is trying to create infinite number of ImageAdapter instances leading to StackOverflowError...
and why do you need another instance of ImageAdapter in ImageAdapter?

Android GSON processing remote JSON runtime exception

I am attempting to write an Android app which casts JSON input. This is my sample input.
I have the following class to serve as the data container:
public class DATA {
public Long id;
public String title;
public String author;
public String url;
public String date;
public String body;
public DATA() {
// TODO Auto-generated constructor stub
}
#Override
public String toString(){
return "DATA-Oblect: ID=> " + id + "/nTITLE=> " + title;
}
}
Using the following code:
protected void doInBackground(String... url) {
try{
//create an HTTP client
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost("http://kylewbanks.com/rest/posts");//url[0]);
//perform the request and check the status code
HttpResponse response = client.execute(post);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == 200){
HttpEntity entity = response.getEntity();
InputStream content = entity.getContent();
content = entity.getContent();
try{
Reader reader = new InputStreamReader(content);
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.setDateFormat("M/d/yy hh:mm a");
Gson gson = gsonBuilder.create();
List<DATA> Data = new ArrayList<DATA>();
Data = Arrays.asList(gson.fromJson(reader, DATA[].class));
content.close();
}catch(Exception ex){
Log.e(TAG, "JSON parse failed due to: " + ex);
}
}else{
Log.e(TAG, "Server response code: " + statusLine.getStatusCode());
}
}catch(Exception ex){
Log.e(TAG, "HTTP-Post failed due to: " + ex);
}
}
I get the following exception error:
JSON parse failed due to: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
What am I doing wrong?
Update
The following the the my main activity code:
public class MainActivity extends Activity {
private List<DATA> Data;
public static final String jsonSource = "http://kylewbanks.com/rest/posts";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
// DataRetriever("http://kylewbanks.com/rest/posts");
new DataRetriever(this.getApplicationContext()).execute(jsonSource);
}
/**
* Callback function for handling retrieved data from the
* DATARetrieve class
* #param Data
*/
public void DataListDrop(List<DATA> Data){
this.Data = Data;
Toast.makeText(MainActivity.this, "Testing ... testing!", Toast.LENGTH_SHORT).show();
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
for(DATA data : MainActivity.this.Data){
Toast.makeText(MainActivity.this, data.title, Toast.LENGTH_SHORT).show();
}
}
});
}
/**
* Callback function for responding no-data return from the
* DATARetrieve class
*/
private void NoData(){
runOnUiThread(new Runnable() {
#Override
public void run(){
Toast.makeText(MainActivity.this, "No data to process! Checkout LogCat.", Toast.LENGTH_SHORT).show();
}
});
}
}

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