Like my title says, i'm looking for an equivalent of getActivity() in my ActionBarActivity class in my Android project.
I want to pass an Activity parameter in AsyncTask declaration object, because i'm using an Activity object in my custom AsyncTask extended class
Here an example simplest code of my project
public class EventCreator extends ActionBarActivity {
private Context context;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_even_creator);
View v = getLayoutInflater().inflate(R.layout.activity_even_creator,null);
this.context = this.getBaseContext();
final Button createButton = (Button)findViewById(R.id.createEventButton);
createButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
AsyncTask<Void,Void,Boolean> eventCreatorSend = new SendEvents(/* here need activity object */);
eventCreatorSend.execute();
}
});
}
class SendEvents extends AsyncTask<Void,Void,Boolean> {
public Activity act;
SendEvents(Activity a) {
this.act = a;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
((LinearLayout)act.findViewById(R.id.layout_loader_create_event)).setVisibility(View.VISIBLE);
}
#Override
protected Boolean doInBackground(Void... params) {
SystemClock.sleep(5000);
return true;
}
#Override
protected void onPostExecute(Boolean params) {
if (params){
((LinearLayout)act.findViewById(R.id.layout_loader_create_event)).setVisibility(View.GONE);
act.finish();
}
else {
((LinearLayout)act.findViewById(R.id.layout_loader_create_event)).setVisibility(View.VISIBLE);
Toast.makeText(act,"Fail to send event",Toast.LENGTH_SHORT).show();
}
}
};
}
In a time, i thought use getParent() from ActionBarActivity class, but it return a null object.
So how to get the Activity object i want in ActionBarActivity class ?
Try nameofactivity.this instead getActivity()
I always use getActivity() in Fragments Activities and .this in any other kind of Activity.
Oh damn !
I just found a solution just after posting my ask.
I use MyClass.this, and it's done. Like this :
AsyncTask<Void,Void,Boolean> eventCreatorSend = new SendEvents(EventCreator.this);
eventCreatorSend.execute();
Hope that's can help someone !
The easiest way is an Activity variable
// in your fragment
Activity myActivity;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
//fragment shouts "i know my father!!!"
myActivity = activity; //
}
now your activity instance(The father) can be represented anywhere
Related
Previous I haved that AsyncTask on main activity and called with:
new SyncGetLocations(ActivityMain.this).execute();
Now,I move it to a fragment and don't know now how to call it from MainActivity.
AsyncTask look alike :
private static class SyncGetLocations extends AsyncTask<Void, Void, Void> {
private WeakReference<ActivityMap> activityReference;
SyncGetLocations(ActivityMap context) {
activityReference = new WeakReference<>(context);
}
#Override
protected void onPreExecute() {
}
#Override
protected Void doInBackground(Void... voids) {
}
#Override
protected void onPostExecute(Void aVoid) {
}
}
Either
From MainActivity find your fragment:
val fragment = getSupportFragmentManager().findFragmentByTag(...) or findFragmentByID(...)
and then call a method in this fragment to launch the asyncTask
fragent.callAsyncTask()
Or
make your asynctask public or remove it from fragment to be its own class and call it froim every where you want
I suggest you to make asyntask not an inner class of fragment of activity it you wants to call it from everywhere
Try attaching Listener to your fragment with a method like
public interface FragmentInteractionListener{
void onClick();
}
In your fragment
private FragmentInteractionListener fragmentListener;
#Override
public void onDetach() {
super.onDetach();
fragmentListener = null;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof FragmentInteractionListener) {
fragmentListener = (FragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement FragmentInteractionListener");
}
}
And under onClick event call it like this
fragmentListener.onClick();
Then in your activity implement the FragmentInteractionListener
OR
((SomeActivity)getActivity()).someMethod();
Hi there I'm thinking about what is the correct and best way to handle Activity, Fragment, AsyncTask and DialogFragments together.
My current state is that I start my Activity and replace its ContentView with my Fragment, in which I got an EditText and one Button.
Tapping my Button executes an AsyncTasks which Requests random things and takes some time. Meanwhile I display a DialogFragment begging for patience.
Desired behavior is that, e.g. I rotate my screen my DialogFragment keeps being displayed for the time my AsyncTask is running. After that I want to show up a simple toast displaying the information I got from my HttpRequest.
Compact overview about how I thought it would work:
BaseFragment keeps a WeakReference to the Activity it's attached to
AsyncTask keeps a WeakReference to Fragment which exectures it
AsyncTasks onPreExecute() shows up the DialogFragment
AsyncTasks onPostExecute() dissmisses the DialogFragment
BaseFragment holds DialogFragment
Unfortunately this is not the way it works, on orientation change my DialogFragment keeps being displayed and no toast is showing up.
What am I doing wrong ?
public class BaseFragment extends Fragment{
private static final String TAG = BaseFragment.class.getSimpleName();
protected WeakReference<AppCompatActivity> mActivity;
private TemplateDialogFragment dialogFragment;
public WeakReference<AppCompatActivity> getAppCompatActivity(){ return mActivity; }
#Override
public void onAttach(Context context) {
if(!(context instanceof AppCompatActivity)) {
throw new IllegalStateException(TAG + " is not attached to an AppCompatActivity.");
}
mActivity = new WeakReference<>((AppCompatActivity) context);
super.onAttach(context);
}
#Override
public void onDetach() {
mActivity = null;
super.onDetach();
}
#Override
public void onStart() {
super.onStart();
showContent();
}
public void showContent(){
}
public void showDialog(String title, String content){
dialogFragment = new TemplateDialogFragment();
Bundle bundle = new Bundle();
bundle.putString(TemplateDialogFragment.DIALOG_TITLE, title);
bundle.putString(TemplateDialogFragment.DIALOG_MESSAGE, content);
dialogFragment.setArguments(bundle);
dialogFragment.show(getFragmentManager(), TemplateDialogFragment.FRAGMENT_TAG);
}
public void notifyTaskFinished(String result) {
dismissDialog();
if(mActivity != null && !mActivity.get().isFinishing()) {
Toast.makeText(mActivity.get().getApplicationContext(), result, Toast.LENGTH_LONG).show();
}
}
private void dismissDialog(){
if(dialogFragment != null && dialogFragment.isAdded()) {
dialogFragment.dismissAllowingStateLoss();
}
}
}
...
public class TemplateFragment extends BaseFragment {
private static final String TAG = TemplateFragment.class.getSimpleName();
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.test_fragment, container, false);
}
#Override
public void showContent() {
super.showContent();
Button startTask = (Button) getAppCompatActivity().get().findViewById(R.id.button0);
final BaseFragment instance = this;
startTask.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
CustomAsyncTask task = new CustomAsyncTask(instance);
EditText input = (EditText) getAppCompatActivity().get().findViewById(R.id.text0);
task.execute(input.getText().toString());
}
});
}
private static class CustomAsyncTask extends AsyncTask<String, Void, String> {
WeakReference<BaseFragment> weakBaseFragmentReference;
private CustomAsyncTask(BaseFragment fragment) {
weakBaseFragmentReference = new WeakReference<>(fragment);
}
#Override
protected void onPreExecute() {
super.onPreExecute();
weakBaseFragmentReference.get().showDialog("Executing", "Working on the request...");
}
#Override
protected String doInBackground(String... params) {
HttpURLConnection con = HttpUrlConnectionFactory.createUrlConnection("https://www.httpbin.org/bytes/" + (params[0] == null ? "1" : params[0]));
return HttpRequester.doGet(con).getResponseAsString();
}
#Override
protected void onPostExecute(String response) {
super.onPostExecute(response);
if(weakBaseFragmentReference.get() == null) {
return;
}
weakBaseFragmentReference.get().notifyTaskFinished(response);
}
}
}
*Edit:
After some time researching this theme I'm sure a Service is the best solution for most of my field of use. Also I used AsyncTaskLoaders a lot, because there is a smooth control of lifecycle....
Use progress bar instead of DialogFragment.
AsyncTask should only be used for tasks that take quite few seconds.
AsyncTask doesn't respect Activity lifecycle, and can lead to memory leaks.
Check some gotchas.
You can try AsyncTaskLoader to survive configuration changes.
I have a class which extends Activity.
public class MyActivity extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.id,someactivitylayout);
new Game(getApplicationContext());
}
My Game class looks like
public class Game{
Game(final Context context){
cell.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
/* here i need to call runOnUIThread*/
}
}
}
My code does not have any syntax errors, so it compiles fine.
In the place where i have to call runOnUIThread, i have tried
Thread t = new Thread() {
public void run() {
while (progressBar.getProgress() < 100) {
((Activity) context).runOnUiThread(new unnable() {
public void run() {
}
});
}
};
t.start();
But when i try to cast context to Activity it gives an exception
java.lang.ClassCastException: android.app.Application cannot be cast to android.app.Activity
Why is it not possible to cast context to Activity??
I have tried many ways but did not find anyway to get Activity in my Game class.
Is there any way to do that??
You are sending ApplicationContext to the Game class. Just replace the getApplicationContext() with this to pass the Activity Context. It will work.
It should be new Game(this)
try with
public class MyActivity extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.id,someactivitylayout);
new Game(this);
}
}
Update1
activity:
public Integer _number = 0;
#Override
public void onCreate(Bundle savedInstanceState) {
if (_number >0)
{
Log.d("onSuccessfulExecute", ""+_number);
}
else
{
Log.d("onSuccessfulExecute", "nope empty songs lists");
}
}
public int onSuccessfulExecute(int numberOfSongList) {
_number = numberOfSongList;
if (numberOfSongList >0)
{
Log.d("onSuccessfulExecute", ""+numberOfSongList);
}
else
{
Log.d("onSuccessfulExecute", "nope empty songs lists");
}
return numberOfSongList;
}
end Update1
UPDATE: AsynchTask has its own external class.
How to pass an value from AsyncTask onPostExecute()... to activity
my code does returning value from onPostExecute() and updating on UI but i am looking for a way to set the activity variable (NumberOfSongList) coming from AsynchTask.
AsyncTask class:
#Override
public void onPostExecute(asynctask.Payload payload)
{
AsyncTemplateActivity app = (AsyncTemplateActivity) payload.data[0];
//the below code DOES UPDATE the UI textView control
int answer = ((Integer) payload.result).intValue();
app.taskStatus.setText("Success: answer = "+answer);
//PROBLEM:
//i am trying to populate the value to an variable but does not seems like the way i am doing:
app.NumberOfSongList = payload.answer;
..............
..............
}
Activity:
public Integer NumberOfSongList;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//Several UI Code
new ConnectingTask().execute();
Log.d("onCreate", ""+NumberOfSongList);
}
What about using a setter method? e.g.
private int _number;
public int setNumber(int number) {
_number = number;
}
UPDATE:
Please look at this code. This will do what you're trying to accomplish.
Activity class
public class TestActivity extends Activity {
public int Number;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
Button btnDisplay = (Button) findViewById(R.id.btnDisplay);
btnDisplay.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast toast = Toast.makeText(v.getContext(), "Generated number: " + String.valueOf(Number), Toast.LENGTH_LONG);
toast.show();
}
});
new TestTask(this).execute();
}
}
AsyncTask class
public class TestTask extends AsyncTask<Void, Void, Integer> {
private final Context _context;
private final String TAG = "TestTask";
private final Random _rnd;
public TestTask(Context context){
_context = context;
_rnd = new Random();
}
#Override
protected void onPreExecute() {
//TODO: Do task init.
super.onPreExecute();
}
#Override
protected Integer doInBackground(Void... params) {
//Simulate a long-running procedure.
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
Log.e(TAG, e.getMessage());
}
return _rnd.nextInt();
}
#Override
protected void onPostExecute(Integer result) {
TestActivity test = (TestActivity) _context;
test.Number = result;
super.onPostExecute(result);
}
}
Just a word of caution: Be very careful when attempting to hold a reference to an Activity instance in an AsyncTask - I found this out the hard way :). If the user happens to rotate the device while your background task is still running, your activity will be destroyed and recreated thus invalidating the reference being to the Activity.
Create a listener.
Make a new class file. Called it something like MyAsyncListener and make it look like this:
public interface MyAsyncListener() {
onSuccessfulExecute(int numberOfSongList);
}
Make your activity implement MyAsyncListener, ie,
public class myActivity extends Activity implements MyAsyncListener {
Add the listener to the constructor for your AsyncTask and set it to a global var in the Async class. Then call the listener's method in onPostExecute and pass the data.
public class MyCustomAsync extends AsyncTask<Void,Void,Void> {
MyAsyncListener mal;
public MyCustomAsync(MyAsyncListener listener) {
this.mal = listener;
}
#Override
public void onPostExecute(asynctask.Payload payload) {
\\update UI
mal.onSuccessfulExecute(int numberOfSongList);
}
}
Now, whenever your AsyncTask is done, it will call the method onSuccessfulExecute in your Activity class which should look like:
#Override
public void onSuccessfulExecute(int numberOfSongList) {
\\do whatever
}
Good luck.
I have doInBackground(). after function I want to change some TextView on MainActivity.
but When I trigger the function on main activity I got NullPointerException on TextView line.
protected String doInBackground(Object... arguments) {
some code..
return result;
}
#Override
protected void onPostExecute(String result) {
if(result!=null)
new MainActivity().setScoreListUpdate(result);
}
MainActivity:
public void setScoreListUpdate(String settings)
{
String[] yeniscore = settings.split("\\|");
if(yeniscore.length > 1)
{
birinci.setText(yeniscore[1]); << NULLPOINTEREXC.
}
}
The reason this gives a NullPointerException is that you create a new instance of MainActivity instead of working on your existing one.
What you need to do is pass a reference to your Activity to the AsyncTask and then call your method on that reference.
So in your AsyncTask-class you will have a variable:
private MainActivity myMainActivity;
Add a constructor to your AsyncTask-class:
public MyAsyncTaskClassName( MainActivity activity ) {
myMainActivity = activity;
}
Then in onPostExecute you do:
myMainActivity.setScoreListUpdate(result);
Use
MainActivity.this.setScoreListUpdate(result);
instead of
new MainActivity().setScoreListUpdate(result);
in yout postExecute method.
Also, TextView called birinci should be a field in your MainActivity class, not just a variable in the onCreate method for example.
EDIT: It works like this in my program. Check out the differences.
public class DeviceSettingsStatsActivity extends ListActivity {
AsyncTask<Void, Integer, ListAdapter> task = null;
ListAdapter listAdapter = null;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
task = new ComputeTask().execute();
}
protected void viewComputeResult(ListAdapter result) {
setListAdapter(result);
}
private class ComputeTask extends AsyncTask<Void, Integer, ListAdapter> {
#Override
protected ListAdapter doInBackground(Void... params) {
// some stuff
}
#Override
protected void onPostExecute(ListAdapter result) {
DeviceSettingsStatsActivity.this.viewComputeResult(result);
}
}
}