I've got a Main Activity which is a search interface, when the user clicks a result in the list, the result details are displayed in a Fragment. The Main Activity has an Action Bar, but in the details Fragment, the Action Bar is hidden. To hide the Action Bar in the Fragment, I'm calling a method in the Main Activity from the Fragment Activity like this: ((SearchInterface)getActivity()).hideABar();. Then when the user clicks the back button, they go back to the search interface and the Action Bar reappears. Doing that is a bit more complex than simply calling a method. I set up an Interface in the Main Activity and override the method in the Fragment like this:
Main Activity:
public interface Callback {
public void onBackPressedCallback();
}
#Override
public void onBackPressed() {
super.onBackPressed();
if(fragBackPressed != null)
fragBackPressed.onBackPressedCallback();
checkActionBarState();
}
...
public void checkActionBarState(){
bar_AB = getSupportActionBar();
boolean barVisible = bar_AB.isShowing();
if(barVisible){
Toast.makeText(getApplicationContext(),"ActionBar WAS Visible",Toast.LENGTH_LONG).show();
}else{
Toast.makeText(getApplicationContext(),"ActionBar WAS NOT Visible",Toast.LENGTH_LONG).show();
bar_AB.show();
}
}
Fragment:
#Override
public void onBackPressedCallback() {
Log.d("SSIVideoFrag", "checking action bar state");
}
So now, when the user presses the Back button while in the Details Fragment, they go back to Main Activity and the Action Bar reappears. Now I'd like to add a button in the Details Fragment that does what clicking the Back button does, but I can't figure out how to do it. I don't know how to override the onBackPressedCallback() method from within the onClick of a Button:
back_BTN.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
//--- what to do here?
}
});
simple:
getFragmentManager().popBackStack();
https://developer.android.com/reference/android/app/FragmentManager.html#popBackStack()
ps.: that's not an actual back press, your onBackPressed will not be called. But the fragment will be removed, just like in a back press.
Related
In my Application, i'm transitioning to a DetailsFragment when the user clicks on a list item. and there are TWO options to be back at the main Fragment (the List Fragment).
Press the back button. (no problem here, because I handle this in onBackPressed() in MainActivity)
Press the Toolbar back arrow (Here is my problem).
When the user presses the toolbar back arrow, I call the following
getActivity().getSupportFragmentManager().popBackStack();
how can I intercept this event in MainActivity?
(There are some manipulations I am doing in MainActivity when the List Fragment is visible to the user.
Just put this code
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onBackPressed();
}
});
I have an implementation of fragment as explained here. I have expanded the BaseFragment class to handle navigation icon onClickListener. The code for that looks like this,
private void onBackButtonPressed(int tag)
{
switch (tag)
{
case Global.DISPLAY_STORE:
{
setTitle("Loyalty Cards",Color.BLACK);
setToolBar(getResources().getColor(R.color.white), Global.ADD_CARD,R.drawable.add_round_btn);
break;
}
case Global.ADD_CARD:
{
setTitle("Wallet", Color.WHITE);
setToolBar(getResources().getColor(R.color.colorPrimary), Global.DISPLAY_STORE,R.drawable.icon_shopping);
getFragmentManager().popBackStack();
break;
}
case Global.CARD_DETAILS:
{
setTitle("Loyalty Cards",Color.BLACK);
setToolBar(getResources().getColor(R.color.white), Global.ADD_CARD,R.drawable.add_round_btn);
getFragmentManager().popBackStack();
break;
}
}
}
I am using this block of code to change the ToolBar icons and colors when back button is pressed.This code resides in BaseFragment.
Here is how I implement the code to handle back press,
I have my fragment extending the BaseFragment
public class CardDetailsFragment extends BaseFragment
Now inside the BaseFragment onCreate I have this code,
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mainActivity = (MainActivity) getActivity();
ImageButton righBarButton = (ImageButton) mainActivity.getToolbar().findViewById(R.id.btn_ToolBarRightBtn);
righBarButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onRighBarButtonClicked(Integer.parseInt(v.getTag().toString()));
}
});
mainActivity.getToolbar().setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
onBackButtonPressed(BACK_BUTTON_TAG);
}
});
getFragmentManager().addOnBackStackChangedListener(this);
shouldDisplayHomeUp();
}
By this every fragments back button press and the right bar button item click in toolbar are handled.
Consider the scenario I have three fragments A , B and C.
From Fragment A I open Fragment B and Then Fragment C. Now From fragment C I click the back button to reach fragment B. The back button event is handled by above code and it works fine.
Now from Fragment B, I click the back button to reach Fragment A. But when I click back button I am getting exception
java.lang.IllegalStateException: Fragment CardDetailsFragment{d8b35b5} not attached to Activity
at android.support.v4.app.Fragment.getResources(Fragment.java:636)
here the CardDetailsFragment is the FragmentC, but I am clicking the
back button from Fragment B
The first time the user presses the back button, Fragment C is no longer necessary and thus it is detached from the activity. The problem lies in the fact that even though Fragment C is detached, it is still registered as a listener for back stack change events.
The second time the user presses the back button, your onBackStackPressed() method is called in Fragment C. When getResources() is executed, there is no activity attachment so getResources() fails.
Something like this in your fragment should fix it:
#Override
public void onDestroy() {
getFragmentManager().removeOnBackStackChangedListener(this);
super.onDestroy();
}
I am working or an app where I have 4 fragments in viewpager and floating action button (fab). When I click on fab there appear 3 subfabs. Each of them start different activities where user can search data from different fragments. Is it possible to set fab so that if I click on it while I'm in first fragment it'll open an activity for searching inside this fragment, onClick inside second - search for second and etc. The issue is that now clicking on sub fab while I'm in some fragment I can search data from another fragment too and it's a bit weird. I understand question is kinda strange, if something is unclear I'll explain further
You can make FAB button public and implement onClick listener in each fragment.
You should override setUserVisibleHint and put your code onResume so getActivity() will not return null. Fab button will have different actions in different fragments.
Here's an example, inside each fragment when you want Fab click listener:
#Override
public void setUserVisibleHint(boolean visible)
{
super.setUserVisibleHint(visible);
if (visible && isResumed())
{
onResume();
}
}
#Override
public void onResume()
{
super.onResume();
if (!getUserVisibleHint())
{
return;
}
MainActivity mainActivity = (MainActivity)getActivity();
mainActivity.fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//Do what you want
}
});
}
You can check in onclick method of floating action button which fragment is currently opened and calling it.
Call findFragmentById() on FragmentManager and determine which fragment is in your R.id.frameTitle container.
I have 2 Activity(s). Inside 1st Activity there is initially one Fragment
MainActivity.java
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.myactivity);
if(savedInstanceState == null) {
getFragmentManager().beginTransaction().replace(R.id.fragmentContainer, MainFragment.newInstance().commit();
}
}
}
then clicking on a button replaces it with another Fragment.
#Override
public void onClick(View arg0) {
DetailFragment detail = (DetailFragment)getFragmentManager().findFragmentById(R.id.detail);
getFragmentManager().beginTransaction().replace(R.id.detail, detail, "detail").commit();
}
On 2nd Fragment there is another button, clicking on it opens a New Activity.
Intent popUp = new Intent(MainActivity.this, PopUp.class);
popUp.putExtra("CarID", carID);
startActivity(popUp);
From PopUp Activity, pressing device back will go back to MainActivity.
Now the challenge is for the Application's business logic I need to update the ActionBar's title of previous MainActivity when user goes back.
For this I'm listening for onResume() on both MainFragment and DetailFragment. Also when user goes back from DetailFragment to MainFragment I update the ActionBar title with different text.
So I need to know when exactly user goes back from:
1) PopUp Activity > Detail Fragment
2) Detail Fragment > Main Fragment
Currently onResume() is fired on both MainFragment and DetailFragment when PopUpActivity is closed. On MainFragment I can't exactly find out whether onResume() is called for 1st or 2nd case.
What is the best practice to fire onResume() on DetailFragment only when user goes back from PopUpActivity > DetailFragment. In other words, how do I detect from DetailFragment that PopUpActivity is closed without firing onResume() on MainFragment.
I wouldn't mess with onResume() for something like this.
I would suggest doing the following:
Create a Stack<String> for titles.
Implement FragmentManager.OnBackStackChangedListener in your MainActivity.
In your onBackStackChanged() implementation, check if the back stack has been pushed or popped using FragmentManager.getBackStackEntryCount().
If the back stack has been pushed, push the newly-displayed fragment's title to your title stack.
If the back stack has been popped, pop a title and set the title bar with the title at the new top of stack.
If you set a title from a fragment that isn't added to the back stack, pop a title from the title stack and push the newly-displayed fragment's title, i.e. replace the title at the top of the stack.
Invoke your PopupActivity with startActivityForResult() instead of startActivity().
Override onActivityResult() in your MainActivity so that when PopupActivity returns, you set the title bar with the title at the top of stack.
Don't forget to persist your title stack in onSaveInstanceState() in your MainActivity and restore it in onCreate().
That might seem like a lot of work just for maintaining titles, but you will drive yourself crazy trying to do this with onResume.
try it:
#Override
public void onResume() {
super.onResume();
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
// handle back button
return true;
}
return false;
}
});
}
I have a button on an action bar that reflects how many items are in the user's favourites. How can I get this to refresh when the back button is pressed?
try this.
#Override
public void onResume() {
invalidateOptionsMenu();
}
Use this:
#Override
public void onBackPressed() {
//Refresh action bar
}