I'm new to Android programming, and I'd like to create a central database service class which will take care of user data exchange with an external database. For this, I created a service which is started after successful login. I created another class that extends AsyncTask to do the data retrieval.
Now, I wanted the methods for the data retrieval to be stored in the service. I would fire intents to the service from different activities, and with .setAction() I would determine which method to call, or which data to retrieve.
I also created an interface class for handling the AsyncTask results.
Now, from this question I thought that it would be possible to have multiple listeners to one and the same AsyncTask result. But now this seems impossible to achieve: I'd like to retrieve the AsyncTask results in the MainMenuActivity, but I can't create an instance of AsyncUserData there as a delegate for the UserData class. In my example below, the missing piece is a valid instance of AsyncUserData for the UserData class to work with. How could I do it?
Here's the example:
MainMenuActivity
public class MainMenuActivity extends ActionBarActivity implements AsyncUserData {
TextView tvUsername;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_menu);
tvUsername =
(TextView) findViewById(R.id.tvUsername);
TelephonyManager tManager = (TelephonyManager) this.getSystemService(Context.TELEPHONY_SERVICE);
String uid = tManager.getDeviceId();
getDataFromUserSessionService(this, uid);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main_menu, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void retrieveResult(String result) throws JSONException {
JSONObject jsonObject = new JSONObject(result);
String joName;
joName = jsonObject.getJSONObject("name").toString();
user.setName(joName);
tvUsername.setText(joName);
}
public void getDataFromUserSessionService(Context context, String uid) {
Intent intent = new Intent(context, UserSession.class);
intent.setAction(UserSession.ACTION_FETCH_USER_DATA);
intent.putExtra(UserSession.UID, uid);
context.startService(intent);
}
UserSession Service
public class UserSession extends IntentService {
public static final String ACTION_FETCH_USER_DATA = "com.example.blahblah.services.action.read_user_data";
#Override
protected void onHandleIntent(Intent intent) {
if (intent != null) {
utils = new Utils(this);
final String action = intent.getAction();
uid = intent.getStringExtra(UID);
if (ACTION_FETCH_USER_DATA.equals(action)) {
handleUserDataFetch(uid);
}
}
}
private void handleUserDataFetch(String uid) {
String[] parameters = new String[2];
parameters[0] = uid;
parameters[1] = Constants.USER_DATA_FETCH;
UserData userData = new UserData(this);
userData.execute(parameters);
}
UserData AsyncTask Class (the Utils class just has another post method):
public class UserData extends AsyncTask < String, Void, String > {
public AsyncUserData delegate = null;
private Context myContext;
public UserData(Context context) {
myContext = context;
}
#Override
protected String doInBackground(String...params) {
String serverResponse = "";
String uid = params[0];
Utils utils = new Utils(myContext);
String phpName = params[1];
List < NameValuePair > nameValuePairs = new ArrayList < NameValuePair > ();
nameValuePairs.add(new BasicNameValuePair("uid", uid));
try {
serverResponse = utils.passDataToServer(phpName, nameValuePairs);
} catch (IOException e) {
e.printStackTrace();
}
return serverResponse;
}
protected void onPostExecute(String result) {
try {
delegate.retrieveResult(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
};
And the AsyncUserData interface:
public interface AsyncUserData {
void retrieveResult(String result) throws JSONException;
}
You can use a Singleton that stores a reference to the activity
public class ServiceToActivity
{
public ActionBarActivity mainactivity = null;
private static ServiceToActivity singleton = null;
public Class<?> cl = null;
private ServiceToActivity()
{
}
public static ActionBarActivity getSingleton()
{
if(singleton==null)
return null;
return singleton.mainactivity;
}
public static Class<?> getSingletonClass()
{
if(singleton==null)
return null;
return singleton.cl;
}
public static void setSingleton(ActionBarActivity mainactivity, Class<?> cl)
{
if(singleton==null)
singleton = new ServiceToActivity();
singleton.mainactivity = mainactivity;
singleton.cl = cl;
}
}
Then create the singleton before the service is started
public void getDataFromUserSessionService(Context context, String uid) {
Intent intent = new Intent(context, UserSession.class);
intent.setAction(UserSession.ACTION_FETCH_USER_DATA);
intent.putExtra(UserSession.UID, uid);
ServiceToActivity.setSingleton(this,this.getClass()); //create Singleton to store a reference to the activity
context.startService(intent);
}
In UserData retrieve data to the main activity by:
protected void onPostExecute(String result) {
try {
Class<?> cl = ServiceToActivity.getSingletonClass();
Method met = cl.getMethod("retrieveResult", String); //String because result is of type String: you can use result.getClass() instead
met.invoke(cl.cast(ServiceToActivity.getSingleton()), result); // compare it to this ServiceToActivity.getSingleton().retrieveResult(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
It sounds like you might want to use an event bus such as otto
Related
I'm working on app that will use biometric as an option to login. Before I use the actual biometric prompt I need to check one thing from server - I use AsyncTask to do it. So, to sum up - I invoke AsyncTask from Parent Activity (login.java), and then AsyncTask uses biometricUtils.java class, that makes biometric prompt. The point is, I keep passing null instead of context to biometricUtils.java:
Attempt to invoke virtual method 'java.util.concurrent.Executor android.content.Context.getMainExecutor()' on a null object reference at biometricUtils.<init>(biometricUtils.java:34)
I have no idea to pass the context correctly.
Here's my code:
login.java
public class login extends AppCompatActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
Bundle bundle = getIntent().getExtras();
final boolean flag = false;
final String androidID = bundle.getString("androidID");
final Activity thisActivity = this;
final Context context = getApplicationContext();
// login using biometrics
Button btnBiometricLogin = findViewById(R.id.btnBiometricLogin);
btnBiometricLogin.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
checkAndroidID async = new checkAndroidID(context);
async.getParentActivity(thisActivity);
async.setFlag(flag);
async.execute(androidID);
}
});
}
}
checkAndroidID.java
public class checkAndroidID extends AsyncTask <String, Void, String> {
openHTTP openHTTP = new openHTTP();
requestHTTP requests = new requestHTTP();
Activity parentActivity;
private WeakReference<Context> contextRef;
Boolean flag;
public checkAndroidID(Context context){
contextRef = new WeakReference<>(context);
}
public void getParentActivity(Activity parentActivity){
this.parentActivity = parentActivity;
}
public void setFlag (Boolean flag){
this.flag = flag;
}
#Override
protected String doInBackground(String... strings) {
try {
HttpURLConnection httpConn = openHTTP.prepareConnection("url");
String json = "{ \"androidID\": \"" + strings[0] + "\" }";
requests.sendData(json, httpConn);
return requests.receiveData(httpConn);
} catch (Exception e){
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String s) {
String[] result = s.split(";");
Context ctx = contextRef.get();
if (result[0].equals("TRUE")) flag = true;
if (!flag) Toast.makeText(parentActivity, "Biometric authentication is now unavailable." +
" Please login using username and password", Toast.LENGTH_SHORT).show();
else {
biometricUtils biometrics = new biometricUtils(ctx);
biometrics.getParentActivity(parentActivity);
biometrics.getUsername(result[1]);
biometrics.inovkeBiometricPrompt();
}
super.onPostExecute(s);
}
}
and biometricUtlis.java
public class biometricUtils {
Activity parentActivity;
String username;
Context context;
public void getParentActivity(Activity parentActivity){
this.parentActivity = parentActivity;
}
public void getUsername(String s){
this.username = s;
}
public biometricUtils(Context context){
this.context = context;
}
// creating a variable for our Executor
Executor executor = ContextCompat.getMainExecutor(context); // LINE 34
// this will give us result of AUTHENTICATION
final BiometricPrompt biometricPrompt = new BiometricPrompt((FragmentActivity) parentActivity, executor, new BiometricPrompt.AuthenticationCallback() {
#Override
public void onAuthenticationError(int errorCode, #NonNull CharSequence errString) {
super.onAuthenticationError(errorCode, errString);
}
// THIS METHOD IS CALLED WHEN AUTHENTICATION IS SUCCESS
#Override
public void onAuthenticationSucceeded(#NonNull BiometricPrompt.AuthenticationResult result) {
super.onAuthenticationSucceeded(result);
Intent intent = new Intent(parentActivity.getApplicationContext(), tmp.class);
intent.putExtra("username", username);
parentActivity.startActivity(intent);
}
#Override
public void onAuthenticationFailed() {
super.onAuthenticationFailed();
}
});
// creating a variable for our promptInfo
// BIOMETRIC DIALOG
final BiometricPrompt.PromptInfo promptInfo = new BiometricPrompt.PromptInfo.Builder().setTitle("Biometrical login")
.setDescription("Place your fingerprint on scanner to proceed").setNegativeButtonText("Cancel").build();
public void inovkeBiometricPrompt() {
biometricPrompt.authenticate(promptInfo);
}
}
In my app, I use a Contacts database and display those contacts using a RecyclerView . When I click on a contact, I want to fetch its data from the tables in the DB, and load them in a new Activity, ContactCard. I have an AsyncTask() which fetches the PhoneNumber objects that match the selected contactId, but I will also need to retrieve the Address and Email objects from the other tables.
I would like to be able to start the activity after all the relevant data is fetched, and I tried doing this in the activity with the Contacts RecyclerView, but the application crashes as the data has not been fetched yet.
I can call the new activity using an intent, but how can I ensure data from different tables is fetched first, before I start the new activity (which effectively displays this data)?
Some of my code:
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public List<PhoneNumber> fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(List<PhoneNumber> result) {
super.onPostExecute(result);
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
// for (PhoneNumber pn : result) {
// Toast.makeText(mContext, pn + "", Toast.LENGTH_SHORT).show();
// }
}
}.execute();
return returnedNumbers;
}
public List<PhoneNumber> getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
}
ContactsFragment:
adapter.setOnItemClickListener(
contact -> {
Intent viewContact = new Intent(getActivity(), WorksideContactCard.class);
viewContact.putExtra(WORKSIDE_CONTACT, contact);
PhoneNumberRepository phoneNumberRepository =
new PhoneNumberRepository(getActivity().getApplicationContext());
List<PhoneNumber> phoneNumberList;
phoneNumberList = phoneNumberRepository.getPhoneNumbers(contact.getId());
ArrayList<PhoneNumber> arrlistPhoneNumbers =
new ArrayList<>(phoneNumberList);
viewContact.putParcelableArrayListExtra(
WORKSIDE_CONTACT_PHONE_NO, arrlistPhoneNumbers);
startActivity(viewContact);
}
You can do this when you click on an item start the asyntask like this
adapter.setOnItemClickListener(
contact -> {
PhoneNumberRepository phoneNumberRepository =
new PhoneNumberRepository(getActivity().getApplicationContext());
List<PhoneNumber> phoneNumberList;
phoneNumberRepository.getPhoneNumbers(contact.getId());
}
and change your PhoneNumberRepository to this class
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public void fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(List<PhoneNumber> result) {
super.onPostExecute(result);
Intent viewContact = new Intent(context, WorksideContactCard.class);
ArrayList<PhoneNumber> arrlistPhoneNumbers =
new ArrayList<>(result);
viewContact.putParcelableArrayListExtra(
WORKSIDE_CONTACT_PHONE_NO, arrlistPhoneNumbers);
context.startActivity(viewContact);
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
}
}.execute();
}
public void getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
}
store the contacts in a list in the doInBackground() method and start an intent to the new activity in the onPostExecute() method and with this intent pass the list of contacts as intent.extra() variables, retrieve and use them in the called activity.
Change your repository class to something like this
public class PhoneNumberRepository {
private WorksideDatabase worksideDatabase;
private List<PhoneNumber> returnedNumbers;
private Context mContext;
private boolean dataDownloaded;
public PhoneNumberRepository(Context context) {
String DB_NAME = "workside_database";
worksideDatabase = Room.databaseBuilder(context, WorksideDatabase.class, DB_NAME).build();
mContext = context;
}
public List<PhoneNumber> fetchPhoneNumbers(final int id) {
new AsyncTask<Integer, Void, List<PhoneNumber>>() {
#Override
protected List<PhoneNumber> doInBackground(Integer... ids) {
returnedNumbers = worksideDatabase.phoneNumberDao().getPhoneNumbersById(id);
System.out.println(returnedNumbers);
for (PhoneNumber pn : returnedNumbers) {
System.out.println("Number: " + pn.getPhoneNumber());
}
return returnedNumbers;
}
// This runs in UI when background thread finishes
#Override
protected void onPreExecute(List<PhoneNumber> result) {
//set flag to false when download starts
dataDownloaded = false;
}
// This runs in UI when background thread finishes
#Override
protected void onPostExecute(Object obj) {
super.onPostExecute(result);
//set flag to true once download completes, you can also check if response is null and update it accordingly
dataDownloaded = true;
System.out.println("Entered onPostExecute of fetchPhoneNumbers");
// for (PhoneNumber pn : result) {
// Toast.makeText(mContext, pn + "", Toast.LENGTH_SHORT).show();
// }
}
}.execute();
return returnedNumbers;
}
public List<PhoneNumber> getPhoneNumbers(int id) {
return fetchPhoneNumbers(id);
}
public boolean isDataDownloaded(int id) {
return dataDownloaded;
}
}
Use this function in onItemClick() whether your data is downloaded or not
if(phoneNumberRepository.isDataDownloaded()) {
//code to fetch data from phonenumberrepo and start activity
}
Hi I'm quite new to Java, I wonder how to call a void method from another activity, when I already moved to new activity. For example, I want to call
onCreate(Bundle state)
from PocketSphinxActivty.java
in my new activity SMSReaderMain.java
I already tried
PocketSphinxActivity ps = new PocketSphinxActivity();
ps.onCreate(null);
It gives no error, but when SMSReaderMain.java activity start it suddenly force close and not responding in the actual device.
I also try to change into ps.onCreate(this) or ps.onCreate(SMSReaderMain.this) but it gives
The method setupRecognizer(File) in the type PocketSphinxActivity is not applicable for the arguments
(SMSReaderMain)
Here's the complete code, and I want to call almost all of method there in my new activity SMSReaderMain.java
PocketSphinxActivity.java
package edu.cmu.pocketsphinx.demo;
public class PocketSphinxActivity extends Activity implements
RecognitionListener {
//keyword yang digunakan dalem program untuk set ke even2 tertentu
private static final String KWS_SEARCH = "wakeup";
private static final String FORECAST_SEARCH = "forecast";
private static final String DIGITS_SEARCH = "drive mode";
private static final String MENU_SEARCH = "menu";
private static final String KEYPHRASE = "ok";
private SpeechRecognizer recognizer;
private HashMap<String, Integer> captions;
#Override
public void onCreate(Bundle state) {
super.onCreate(state);
// Buat nyiapin User Interface
captions = new HashMap<String, Integer>();
captions.put(KWS_SEARCH, R.string.kws_caption);
captions.put(MENU_SEARCH, R.string.menu_caption);
//captions.put(DIGITS_SEARCH, R.string.digits_caption);
captions.put(FORECAST_SEARCH, R.string.forecast_caption);
setContentView(R.layout.main);
((TextView) findViewById(R.id.caption_text))
.setText("Preparing the recognizer");
// Recognizer initialization is a time-consuming and it involves IO,
// so we execute it in async task
new AsyncTask<Void, Void, Exception>() {
#Override
protected Exception doInBackground(Void... params) {
try {
Assets assets = new Assets(PocketSphinxActivity.this);
File assetDir = assets.syncAssets();
setupRecognizer(assetDir);
} catch (IOException e) {
return e;
}
return null;
}
#Override
protected void onPostExecute(Exception result) {
if (result != null) {
((TextView) findViewById(R.id.caption_text))
.setText("Failed to init recognizer " + result);
} else {
switchSearch(KWS_SEARCH);
}
}
}.execute();
}
//nyocokin keyword dan pindah2 menu
#Override
public void onPartialResult(Hypothesis hypothesis) {
String text = hypothesis.getHypstr();
try {
Intent i= null;
if (text.equals(KEYPHRASE)) {
switchSearch(MENU_SEARCH);
}
if (text.equals(DIGITS_SEARCH)) {
//panggil class SMSReaderMain
recognizer.stop();
i = new Intent(getApplicationContext(),SMSReaderMain.class);
startActivity(i);
}
if (text.equals(FORECAST_SEARCH)) {
switchSearch(FORECAST_SEARCH);
}
//else
//((TextView) findViewById(R.id.result_text)).setText(text);
} catch (Exception e) {
e.printStackTrace();
}
}
//nge pop up keyword yang sesuai kita ucapin sama library yg udah ada
#Override
public void onResult(Hypothesis hypothesis) {
((TextView) findViewById(R.id.result_text)).setText("");
if (hypothesis != null) {
String text = hypothesis.getHypstr();
makeText(getApplicationContext(), text, Toast.LENGTH_SHORT).show();
}
}
#Override
public void onBeginningOfSpeech() {
}
//kembali ke menu utama
/*#Override
public void onEndOfSpeech() {
if (DIGITS_SEARCH.equals(recognizer.getSearchName())
|| FORECAST_SEARCH.equals(recognizer.getSearchName()))
switchSearch(KWS_SEARCH);
}**/
//nampilin caption yg di mau sesuai dengan keyword
public void switchSearch(String searchName) {
recognizer.stop();
recognizer.startListening(searchName);
String caption = getResources().getString(captions.get(searchName));
((TextView) findViewById(R.id.caption_text)).setText(caption);
}
//inisiasi recognizer di awal
public void setupRecognizer(File assetsDir) {
File modelsDir = new File(assetsDir, "models");
recognizer = defaultSetup()
.setAcousticModel(new File(modelsDir, "hmm/en-us-semi"))
.setDictionary(new File(modelsDir, "dict/cmu07a.dic"))
.setRawLogDir(assetsDir).setKeywordThreshold(1e-20f)
.getRecognizer();
recognizer.addListener(this);
// Create keyword-activation search.
recognizer.addKeyphraseSearch(KWS_SEARCH, KEYPHRASE);
// Create grammar-based searches.
File menuGrammar = new File(modelsDir, "grammar/mulai.gram");
recognizer.addGrammarSearch(MENU_SEARCH, menuGrammar);
//File digitsGrammar = new File(modelsDir, "grammar/digits.gram");
//recognizer.addGrammarSearch(DIGITS_SEARCH, digitsGrammar);
// Create language model search.
File languageModel = new File(modelsDir, "lm/weather.dmp");
recognizer.addNgramSearch(FORECAST_SEARCH, languageModel);
}
#Override
public void onEndOfSpeech() {
// TODO Auto-generated method stub
}
}
SMSReaderMAin.java
public class SMSReaderMain extends Activity {
private final int CHECK_CODE = 0x1;
private final int LONG_DURATION = 5000;
private final int SHORT_DURATION = 1200;
private Speaker speaker;
private ToggleButton toggle;
private OnCheckedChangeListener toggleListener;
private TextView smsText;
private TextView smsSender;
private BroadcastReceiver smsReceiver;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//PocketSphinxActivity ps = new PocketSphinxActivity();
//ps.setupRecognizer(null);
//ps.onPartialResult(null);
//ps.onResult(null);
//ps.switchSearch(null);
setContentView(R.layout.main_sms);
//recognizer.startListening(searchName);
toggle = (ToggleButton)findViewById(R.id.speechToggle);
smsText = (TextView)findViewById(R.id.sms_text);
smsSender = (TextView)findViewById(R.id.sms_sender);
toggleListener = new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton view, boolean isChecked) {
if(isChecked){
speaker.allow(true);
speaker.speak(getString(R.string.start_speaking));
}else{
speaker.speak(getString(R.string.stop_speaking));
speaker.allow(false);
}
}
};
toggle.setOnCheckedChangeListener(toggleListener);
checkTTS();
initializeSMSReceiver();
registerSMSReceiver();
}
private void checkTTS(){
Intent check = new Intent();
check.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
startActivityForResult(check, CHECK_CODE);
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode == CHECK_CODE){
if(resultCode == TextToSpeech.Engine.CHECK_VOICE_DATA_PASS){
speaker = new Speaker(this);
}else {
Intent install = new Intent();
install.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
startActivity(install);
}
}
}
private void initializeSMSReceiver(){
smsReceiver = new BroadcastReceiver(){
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
if(bundle!=null){
Object[] pdus = (Object[])bundle.get("pdus");
for(int i=0;i<pdus.length;i++){
byte[] pdu = (byte[])pdus[i];
SmsMessage message = SmsMessage.createFromPdu(pdu);
String text = message.getDisplayMessageBody();
String sender = getContactName(message.getOriginatingAddress());
speaker.pause(LONG_DURATION);
speaker.speak("You have a new message from" + sender + "!");
speaker.pause(SHORT_DURATION);
speaker.speak(text);
smsSender.setText("Message from " + sender);
smsText.setText(text);
}
}
}
};
}
private void registerSMSReceiver() {
IntentFilter intentFilter = new IntentFilter("android.provider.Telephony.SMS_RECEIVED");
registerReceiver(smsReceiver, intentFilter);
}
private String getContactName(String phone){
Uri uri = Uri.withAppendedPath(PhoneLookup.CONTENT_FILTER_URI, Uri.encode(phone));
String projection[] = new String[]{ContactsContract.Data.DISPLAY_NAME};
Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
if(cursor.moveToFirst()){
return cursor.getString(0);
}else {
return "unknown number";
}
}
#Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(smsReceiver);
speaker.destroy();
}
}
This is a really wrong approach to the way of programming in Android. Activities are one of the main core components in an Android application that is managed directly by the OS, which means that the system creates them and are managed by the OS. The onCreate method is part of the lifecycle and it is automatically called by the system. Here you have the activity's lifecycle.
The way of starting a new activity is:
Intent intent = new Intent(mContext, MyActivity.class);
startActivity(intent);
As the activity is instanciated by the system, you cannot call directly to methods on it. The way of communicating between activities is by providing bundle objects in the intent, so in the new Activity you can get the data from:
getIntent().getExtras()
You can also provide backward information by using startActivityForResult instead of startActivity, receiving a result in onActivityResult.
You have the info you need here.
Activity corresponds to something you are going to display on screen. If you are not going to display anything, don't create activities.
In this example you do not need PocketsphinxActivity at all. You can move all the methods of PocketsphinxActivity into your SMSReaderMain activity.
If you want to separate speech recognition code into separate class you can create a separate PocketsphinxRecognizer class but inherit it from Object, not from the Activity.
I am having some problem when trying to pass a String and object to AsyncTask class. So when my button on click, it should pass in a String and an EventReview object into the AsyncTask class:
viewDtlEventBtn.setOnClickListener(new OnClickListener(){
public void onClick(View v){
new GetEventDetailAsyncTask(new GetEventDetailAsyncTask.OnRoutineFinished() {
public void onFinish() {
//Get the values returned from AsyncTask and pass it to another activity
}
}).execute(String.valueOf(eventIDTV.getText()));
}
});
And inside my AsyncTask class, I am getting String as the parameter:
public static class GetEventDetailAsyncTask extends AsyncTask<String, Integer, Double> {
EventController eventCtrl = new EventController();
Context context;
public interface OnRoutineFinished { // interface
void onFinish();
}
private OnRoutineFinished mCallbacks;
public GetEventDetailAsyncTask(OnRoutineFinished callback) {
mCallbacks = callback;
}
public GetEventDetailAsyncTask() {
} // empty constructor to maintain compatibility
public GetEventDetailAsyncTask(Context context){
this.context = context;
}
#Override
protected Double doInBackground(String... params) {
try {
eventCommentModel = eventCtrl.getEventCommentByID(params[0]);
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(Double result) {
if (mCallbacks != null)
mCallbacks.onFinish(); // call interface on finish
}
protected void onProgressUpdate(Integer... progress) {
}
}
So I wonder is there any possible way to pass in a String and EventReview object to the execute() and then when doInBackground(), each execute each method. Any guides?
Thanks in advance.
You can pass String and your custom class' object in Object[] in asynctask.
Object[] obj = new Object[2];
obj[0] = "my data";
obj[1] = myEventReviewObj;
new GetEventDetailAsyncTask().execute(obj);
AsyncTask:
public static class GetEventDetailAsyncTask extends AsyncTask<Object, Integer, Double> {
#Override
protected Double doInBackground(Object... params) {
String paramStr = "";
EventReview eventReview = null;
if(params[0] instanceof String && params[1] instanceof EventReview) {
paramStr = (String) params[0];
eventReview = (EventReview) params[1];
}
else {
eventReview = params[0];
paramStr = params[1];
}
try {
//perform operation using String and Object as per your need
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
}
Hope this helps.
You can change the class to accept Objects as input:
public static class GetEventDetailAsyncTask extends AsyncTask<Object, Integer, Double>
and check if the object is an instance of String or of EventReview
#Override
protected Double doInBackground(Object... params) {
if(params[0] instanceof String) // it is String
else if(params[0] instanceof EventReview) // it is EventReview
}
Create custom constructor and save the passed variables in your AsyncTask:
public static class GetEventDetailAsyncTask extends AsyncTask<String, Integer, Double> {
EventReview eventReview;
private OnRoutineFinished mCallbacks;
String string;
Context context;
public GetEventDetailAsyncTask(OnRoutineFinished callback, String str, EventReview review) {
mCallbacks = callback;
string = str;
eventReview = review;
}
...
}
And then call the AsyncTask by passing your vars:
public void onClick(View v){
new GetEventDetailAsyncTask(
new GetEventDetailAsyncTask.OnRoutineFinished() {
public void onFinish() {
// Get the values returned from AsyncTask and pass it to another activity
}
},
String.valueOf(eventIDTV.getText(),
eventReview).execute());
}
I'm trying to add a database connection inside my asynctask. This the code I'm working on:
DailySync.class:
DownloadSupplierMaster objAsyncTask;
// TODO get all checked items
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.daily_synchronize);
initControls();
objAsyncTask = new DownloadSupplierMaster(this);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.dailysync_menu, menu);
final MenuItem itemSync;
itemSync = menu.findItem(R.id.sync);
itemSync.setOnMenuItemClickListener(new OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
StringBuffer responseText = new StringBuffer();
responseText.append("Selected modules are...\n");
ArrayList<SyncDataItems> itemList = dataAdapter.itemList;
for (int i = 0; i < itemList.size(); i++) {
SyncDataItems itemName = itemList.get(i);
if (itemName.isSelected()) {
responseText.append("\n" + itemName.getItem() );
}
}
objAsyncTask.execute();
return true;
}
});
return super.onCreateOptionsMenu(menu);
}
#Override
public void onTaskComplete(String result) {
}
DownloadTask.class:
public class DownloadTask extends AsyncTask<Void, Void, Void> {
private Activity activity;
private AsyncTaskListener callback;
public DownloadSupplierMaster(Activity act) {
this.activity = act;
this.callback = (AsyncTaskListener)act;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
}
protected Void doInBackground(Void...params) {
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given website URL in JSONfunctions.class
String result = JSONFunctions.getJSONfromURL(URL);
try {
JSONArray jr = new JSONArray(result);
HashMap<String, String> map = new HashMap<String, String>();
String[] keys = { SupplierMaster.TAG_SUPPLIERCODE, SupplierMaster.TAG_SUPPLIERNAME,
SupplierMaster.TAG_SUPPLIERGROUP, SupplierMaster.TAG_SUPPLIERTYPE,
SupplierMaster.TAG_SUPPLIERADDRESS, SupplierMaster.TAG_SUPPLIERADDRESSALT, SupplierMaster.TAG_PHONE1,
SupplierMaster.TAG_PHONE2, SupplierMaster.TAG_FAX,
SupplierMaster.TAG_EMAIL, SupplierMaster.TAG_WEBSITE,
SupplierMaster.TAG_EXPENSEACCOUNT, SupplierMaster.TAG_CONTACTPERSON,
SupplierMaster.TAG_CREDITLIMIT, SupplierMaster.TAG_TOTALCREDIT, SupplierMaster.TAG_TIN,
SupplierMaster.TAG_TAXCODE, SupplierMaster.TAG_TERMS };
for(int i=0;i<jr.length();i++) {
jb = (JSONObject)jr.get(i);
for (String key : keys) {
map.put(key, jb.getString(key));
}
arraylist.add(map);
String suppliercode = jb.getString(SupplierMaster.TAG_SUPPLIERCODE);
String suppliername = jb.getString(SupplierMaster.TAG_SUPPLIERNAME);
String suppliergroup = jb.getString(SupplierMaster.TAG_SUPPLIERGROUP);
String suppliertype = jb.getString(SupplierMaster.TAG_SUPPLIERTYPE);
String supplieraddress = jb.getString(SupplierMaster.TAG_SUPPLIERADDRESS);
String supplieraddressalt = jb.getString(SupplierMaster.TAG_SUPPLIERADDRESSALT);
String phone1 = jb.getString(SupplierMaster.TAG_PHONE1);
String phone2 = jb.getString(SupplierMaster.TAG_PHONE2);
String fax = jb.getString(SupplierMaster.TAG_FAX);
String email = jb.getString(SupplierMaster.TAG_EMAIL);
String website = jb.getString(SupplierMaster.TAG_WEBSITE);
String expenseaccount = jb.getString(SupplierMaster.TAG_EXPENSEACCOUNT);
String contactperson = jb.getString(SupplierMaster.TAG_CONTACTPERSON);
String creditlimit = jb.getString(SupplierMaster.TAG_CREDITLIMIT);
String totalcredit = jb.getString(SupplierMaster.TAG_TOTALCREDIT);
String tin = jb.getString(SupplierMaster.TAG_TIN);
String taxcode = jb.getString(SupplierMaster.TAG_TAXCODE);
String terms = jb.getString(SupplierMaster.TAG_TERMS);
context.dbConnect(); // I'M GETTING A NULLPOINTEREXCEPTION IN THIS LINE!!!!!!!!!!!!
dbHelper.insertORReplaceToSUPPLIERCARD(suppliercode, suppliername, suppliergroup,
suppliertype, supplieraddress, supplieraddressalt, phone1,
phone2, fax, email, website, expenseaccount, contactperson,
creditlimit, totalcredit, tin, taxcode, terms);
dbHelper.close();
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void args) {
callback.onTaskComplete("Test");
}
AysncTaskListener.class:
public interface AsyncTaskListener {
public void onTaskComplete(String result);
}
The problem is, I'm getting a nullpointerexception in context.dbConnect();
What do you think is the problem? Any ideas? I would gladly appreciate your help. Thanks.
Where is this context object coming from? Can you confirm that it has a value?
From a design perspective, I suggest creating a database helper class that is a singleton, that you can then access from the AsyncTask and let it handle the database interactions for the whole application as this will both be easier to handle these sorts of exceptions as well as make it very easy to maintain all the database related code for your app.