Develop Reference

View not updating in OnClickListener

i am trying to make an E-Leaning app.
I have a submit button, that when pressed, sends the user's answer to a server to be evaluated.
During that evaluation, I want to display a loading indicator (I am simply using Android Studio's progress bar).
During the onViewCreated of my fragment, I set the onClickListener as follows:
submit_button.setOnClickListener {
submit_button.isClickable = false
loadingIndicator.visibility = View.VISIBLE
inputFragment.passDataToActivityAndEvaluate()
}
On press, a coroutine is launched that makes an html request. After that, I want to hide the loading spinner before navigating the child fragment
loadingIndicator.visibility = View.INVISIBLE
submit_button.isClickable = true
The idea sounded simple enough, however, I discovered that when trying to make any form of UI change in the OnClickListener, it only gets applied when the evaulation is already done and the app has navigated to the next fragment.

Show Indeterminate Indicator when loading another Activity

I'm trying to show my Indeterminate Progress Indicator When a certain Card is being tapped.
I declared the indicator in my onCreate as follows
mSlider = Slider.from(mCardScroller);
mIndeterminate = mSlider.startIndeterminate();
Then in my onclick I have the following
mIndeterminate.show();
intent = new Intent(getApplicationContext(), CaptureActivity.class);
startActivityForResult(intent, REQUEST_CODE);
I want to show the progress indicator while the QR-Scan activity is being loaded since this takes a few seconds.
However with this the indicator doesn't show up at all. Is there a way to make sure the indicator is being shown while the called upon activity is loading?
When I take out the startActivityForResult() it does start the indicator so I'm pretty sure it has something to do with the lifecycle of the activity, but I'm not sure how I should go about it in this case.

I guess you should put the slider in CaptureActivity instead.
Your slider is hidden. From my understanding, you start the progress bar in the activity which is moved to the background. The whole activity cannot be seen not only the progress bar.
Try moving these code into onCreate of CaptureActivity
mSlider = Slider.from(mCardScroller);
mIndeterminate = mSlider.startIndeterminate();
mIndeterminate.show();

How to refresh the screen when back button is pressed

I have scenario with two screens.
Screen 1 shows data from from API in list format
There is a "+" button in menu bar
Clicking this button takes user to screen 2
User can enter some info on screen 2 and press the "save" button on top of this screen. This does a POST to my API and saves the data.
After saving, I would like to put the user back to screen 1. I've done that with this:
#Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
if (menuItem.getTitle().toString().equalsIgnoreCase("save")) {
new CreateSomethingTask(this,enteredName.getText().toString(), id).execute();
Intent listscreen = new Intent(getApplicationContext(), ShowListActivity.class);
startActivity(listscreen);
return true;
}
return true;
}
However, the added item is not shown. If I close my app and open it again then the item shows up.
Is there a good way to handle this? I like how the Github Android app handles this when creating a new Gist. But I'm not sure how to implement that.

You should start your screen2 with startActivityForResult(). That way you could send a result back and a code and proceed to refresh your screen1. See example : How to manage `startActivityForResult` on Android?

Below function maybe help you, didn't tried.
#Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
callFunctionToRefreshList();
//or redraw data from api
//setContentView(R.layout.activity_book);
}

"Login" activity: ProgressDialog alternative

I have got an activity where the user can enter host name, user name and password and then click on a "Verify credentials" button. Then the credentials will be checked, which will take some time. In the meantime the user should neither be able to change the credentials nor to click on "Verify" again. So, a modal dialog like the ProgressDialog seems perfect for this.
Unfortunately, ProgressDialog has the well-know limitations regarding orientation changes etc. The guide (UI/Dialogs) tells to avoid ProgressDialog at all and use a ProgressBar in the layout instead (like in Progress & Activity). What does this mean? Shall I create another activity with just one progress bar? Or disable all input fields and put a progress bar on top of it? Sounds quite weird to me... whats your preferred solution?

Best thing which I use is:
Put a ProgressBar just beside the Login Button.
I have put a progressbar beside it(Whose visibility is set to View.GONE) in the OnCreate method.
When the user clicks on the Login/Submit button, I set the visibility of the button to View.GONE and visibility of ProgressBar to View.VISIBLE.
It looks good and the user cannot click on the button until the work is done, If an error occurs, toggle the visibility to let the user try again

Like #micro.pravi mentioned in his answer, you can implement the ProgressBar inside your layout. To keep the state after an orientation change you have to use onSaveInstanceState and onRestoreInstanceState to save and restore important values, i.e. private variables, like the private boolean isChecking
public class MyActivity extends Activity {
public boolean isProcessing;
#Override
public void onCreate(Bundle stateBundle) {
super.onCreate(stateBundle);
// Set Layout
setContentView(R.layout.main);
if(stateBundle!=null) {
// read your data here from the bundle
isProcessing = stateBundle.getBoolean("isProcessing");
}
setUiState(isChecking);
}
#Override
protected void onRestoreInstanceState(Bundle stateBundle) {
// Second value of getBoolean is the default value
isProcessing = stateBundle.getBoolean("isProcessing", false);
super.onRestoreInstanceState(stateBundle);
}
#Override
protected void onSaveInstanceState(Bundle stateBundle) {
// Save the critical data
stateBundle.putString("isProcessing", isProcessing);
super.onSaveInstanceState(stateBundle);
}
#Override
protected onResume() {
setUiState(isProcessing);
}
private setUiState(boolean processing) {
textView.setEnabled(!processing);
button.setEnabled(!processing);
progressbar.setVisibility(processing?View.VISIBLE:View.GONE);
}
}
This should be used to saved any critical data on orientation change or when the App is being killed and later restored by the OS. You don't have to save your TextView data, as the defautl View elements already handle this by themselves. Also do not store Image data this way. Instead store the Uri or path to the Url and load it on restore

For temporarily solving your problem, you can continue using the Progress Dialog and put this line in your Login Activity's tag in Manifest.xml file :
android:configChanges="orientation|keyboardHidden|screenSize"
Using this line of code will not affect the Progress Dialog on orientation changes. But it is considered a wrong practice according to Android Development's Documentation.
In the long run, i recommend you to Preserve the states for orientation changes.

How to dim the status bar in a fragment

Im trying to dim the status bar at the bottom of the screen in a fragment, then show it again when the fragment goes away. Here's the code:
#Override
public void onPause()
{
super.onPause();
getActivity().getActionBar().show();
getView().setSystemUiVisibility(View.STATUS_BAR_VISIBLE);
}
#Override
public void onStart()
{
super.onStart();
getActivity().getActionBar().hide();
getView().setSystemUiVisibility(View.STATUS_BAR_HIDDEN);
}
If the user launches my fragment, it works. It dims correctly. But if they hit "back", it seems like the status bar gets shown again correctly, but then after a split second, it goes dim again by itself. Has any one else seen this behavior? I think the system is doing something automatically with the status bar, but I cant figure out what it is. If I take out my call to show the status bar, it still shows it by itseft if the user hits back, but then a split second later, it gets dimmed again.

I had the same issue. I think the problem was that I wasn't setting the visibility on the main content view. I ended up copying the code from HoneycombGallery's ContentFragment.java and that finally worked for me.