Develop Reference

Open bottom sheet dialog only for one time

I have an issue with my Bottom Sheet Dialog. How do make my bottom sheet dialog only open for one time? If I clicked the button twice from my activity, it will open up the dialog twice. How to check whether the dialog is open or not from the activity? If the dialog is open, it will dismiss if I click the button. Here's my code to open the fragment from the activity. Thanks
Bundle bundle = new Bundle();
bundle.putString("outletData", new Gson().toJson(outletData));
BookOutletDialogFragment bookOutletDialogFragment = BookOutletDialogFragment.newInstance();
bookOutletDialogFragment.setArguments(bundle);
bookOutletDialogFragment.show(getSupportFragmentManager(), bookOutletDialogFragment.TAG);

set the flag in your Activity as:-
public static boolean isFragmentShown=false;
modify your onPause() and onStart() method of your fragments as:-
#Override
public void onStart() {
super.onStart();
Log.e( "Fragment is visible", "Fragment is visible");
**YouActivityName**.isFragmentShown = true;
}
#Override
public void onPause() {
super.onPause();
Log.e("Fragment is not visible", "Fragment is not visible");
**YouActivityName**.isFragmentShown = false;
}
And in your click method add this code in your top to check fragment is visible or not:-
if(!isFragmentShown){
Bundle bundle = new Bundle();
bundle.putString("outletData", new Gson().toJson(outletData));
BookOutletDialogFragment bookOutletDialogFragment = BookOutletDialogFragment.newInstance();
bookOutletDialogFragment.setArguments(bundle);
bookOutletDialogFragment.show(getSupportFragmentManager(),
bookOutletDialogFragment.TAG);}

While Afzal Khan's answer is true in my case onPause() method never called after doing something (ex: Pressing button) inside Bottom Sheet Dialog. So I just overrided onDismiss() method as I observed that onDismiss() method is called everytime when you dismiss dialog unlike onPause()
#Override
public void onDismiss(DialogInterface dialog) {
System.out.println("onDismiss() method called");
**YouActivityName**.isFragmentShown = false;
}

back from fragment 2 to fragment 1 but title still that from fragment 2

Every one i have a problem and can't figure how to solve it;
the problem is i has mainActivity that contain toolbar is it's xml
and in onCreate() i add fragment 1 with this code
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
// put the fragment to the Main Activity
mainFragment = (MainFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_container);
if (mainFragment == null) {
mainFragment = MainFragment.newInstance();
getSupportFragmentManager()
.beginTransaction()
.add(R.id.fragment_container, mainFragment)
.commit();
}
} catch (Exception e) {
goToMainFragment();
// Log.v("goToMainFragment()", "goToMainFragment()");
}
}
then i had button for example or from drawer when click on it go to fragment 2 with this code
public void editTimeSheet() {
AddTimeSheetFragment timeSheetFragment = new AddTimeSheetFragment();
Bundle bundle = new Bundle();
bundle.putInt("action", 2);
bundle.putSerializable("timeSheet", timeSheet);
timeSheetFragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction().add(R.id.fragment_container, timeSheetFragment).addToBackStack("stack").commit();
}
and of course in each fragment i change toolbar title using
getActivity().setTitle("some title");
but the problem is when i back using onBackPressed the title not change and still the title that set from fragment 2 , I know why because i change the toolbar title of the activity and when i back to fragment 1 onCreateView not called so the title not changed , i try call fragment lifeCycle methods so any method has called in the back button i will change toolbar title from it but seems no method has call when back
i'm sorry if the question not clear enough but it's the best i write it and describe the problem, thanks for your time

ok nobody answer me and after long time of research i found this and it's work
#Override
public void onHiddenChanged(boolean hidden) {
super.onHiddenChanged(hidden);
if (hidden) {
// Toast.makeText(getContext(), "hide fragment", Toast.LENGTH_SHORT).show();
} else {
// Toast.makeText(getContext(), "show fragment", Toast.LENGTH_SHORT).show();
setToolbarTitle();
}
}
after back to fragment 1 this method is called with hidden value = false

Exiting from Activity with only fragments

My app contains one empty activity and a couple of fragments. The onCreate of the activity replaces the empty view in activity_main.xml with a MainFragment that contains some buttons. Each button launches a separate fragment, and user can navigate from one fragment to another, etc.
On the press of back key, the current fragment correctly gets replaced with the previous fragment, until you get to the MainFragment. When user presses back from MainFragment, it hides the main fragment and you see the white empty background of the main activity. But I want to exit from the activity at this point, as that would be the sensible behaviour.
I am able to achieve this by calling super.onBackPressed() for a second time from onBackPressed if there are no fragments left in the fragment manager.
#Override
public void onBackPressed() {
super.onBackPressed();
FragmentManager manager = getSupportFragmentManager();
List<Fragment> fragments = manager.getFragments();
if (fragments == null || fragments.size() == 0) {
Log.d(TAG, "No more fragments: exit");
super.onBackPressed();
}
}
Is this acceptable thing to do - would it create any issues in the activity workflow? Is there a better/standard way to handle this scenario?

There is no problem to do that, but probably it would be easier if when you add the main fragment to the activity you do NOT call .addToBackStack()

You don't really need to override onBackPressed in your Activity. I would suggest implementing a method for adding fragments in your Activity:
protected void addFragment(Fragment fragment, boolean addToBackStack) {
String tag = fragment.getClass().getName(); //It's optional, may be null
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction()
.add(R.id.your_container_id, fragment, tag);
if (addToBackStack) {
transaction.addToBackStack(tag);
}
transaction.commit();
}
And modify your onCreate method of activity like in the following snippet:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
// Add your fragment only if it is a first launch,
// otherwise it will be restored by system
addFragment(new YourFirstFragment(), false);
}
}
For all other fragments use:
addFragment(new OtherFragment(), true);

how to go back to previous fragment on pressing manually back button of individual fragment?

I have only one activity and multiple fragments in my application.
Two main fragment A(left) and B(right).
Fragment A1 called from A
B1 called from B
B2 called from B1
All fragments have individual back buttons.
So when I press back button of fragment A1, it should go back to A, similarly when Back button from B2 is pressed, B1 appears and from B1 to B and so on.
How to implement this type of functionality?

public void onBackPressed()
{
FragmentManager fm = getActivity().getSupportFragmentManager();
fm.popBackStack();
}

I have implemented the similar Scenario just now.
Activity 'A' -> Calls a Fragment 'A1' and clicking on the menu item, it calls the Fragment 'A2' and if the user presses back button from 'A2', this goes back to 'A1' and if the user presses back from 'A1' after that, it finishes the Activity 'A' and goes back.
See the Following Code:
Activity 'A' - OnCreate() Method:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activityA);
if (savedInstanceState == null) {
Fragment fragInstance;
//Calling the Fragment newInstance Static method
fragInstance = FragmentA1.newInstance();
getFragmentManager().beginTransaction()
.add(R.id.container, fragInstance)
.commit();
}
}
Fragment : 'A1'
I am replacing the existing fragment with the new Fragment when the menu item click action happens:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.action_edit_columns) {
//Open the Fragment A2 and add this to backstack
Fragment fragment = FragmentA2.newInstance();
this.getFragmentManager().beginTransaction()
.replace(R.id.container, fragment)
.addToBackStack(null)
.commit();
return true;
}
return super.onOptionsItemSelected(item);
}
Activity 'A' - onBackPressed() Method:
Since all the fragments have one parent Activity (which is 'A'), the onBackPressed() method lets you to pop fragments if any are there or just return to previous Activity.
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else {
getFragmentManager().popBackStack();
}
}
If you are looking for Embedding Fragments inside Fragments, please refer the link: http://developer.android.com/about/versions/android-4.2.html#NestedFragments

#trueblue's answer got me going with one minor but annoying issue. When there is only one fragment on the backstack and you press back button, that frame is removed and the app remains active with a blank screen. User needed to press back button one more time to exit the app. I modified the original code to the following in order to handle this situation
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else if(getFragmentManager().getBackStackEntryCount() == 1) {
moveTaskToBack(false);
}
else {
getFragmentManager().popBackStack();
}
}
When there is only 1 fragment in the backstack, we are basically telling android to move the whole app to back.
Update (and probably a better answer)
So after doing some more reading around this, I found out that you can add fragment manager transactions to back stack and then android handles back presses automatically and in a desired way. The below code snippet shows how to do that
Fragment fragment; //Create and instance of your fragment class here
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment).addToBackStack(null);
fragmentTransaction.commit();
fragmentTransaction.addToBackStack(null);
The last line shows how you add a transaction to back stack. This solves back press issue for fragments in most situations except for one. If you go on pressing back button, then eventually you will reach a point when there is only one fragment in the back stack. At this point, you will want to do one of the two things
Remove the activity housing the fragment from the back stack of the task in which activity is running. This is because you do not want to end up with a blank activity
If the activity is the only activity in the back stack of the task, then push the task in background.
In my case, it was the later, so I modified the overridden onBackPressed method from my previous answer to look like below
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 1) {
moveTaskToBack(false);
}
else {
super.onBackPressed();
}
}
This code is simpler because it has less logic and it relies on framework than on our custom code. Unfortunately I did not manage to implement code for first situation as I did not need to.

You have to implement your own backstack implementation as explained here.
You can call the popFragments() whenever you click the back button in a fragment and call pushFragments() whenever you navigate from one Fragment to other.

Just Do
getActivity().getFragmentManager().popBackStack();

Try this, Its Work for me.
public void onBackPressed() {
if (mainLayout.isMenuShown()) {
mainLayout.toggleMenu();
} else {
FragmentManager fm = getSupportFragmentManager();
Log.print("back stack entry", fm.getBackStackEntryCount() + "");
if (fm.getBackStackEntryCount() > 1) {
fm.popBackStack();
// super.onBackPressed();
// return;
} else {
if (doubleBackToExitPressedOnce) {
fm.popBackStack();
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Press one more time to exit",
Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 3000);
}
}
}

Back button will traverse in the order, in which Fragments were added to backstack. This is provided as a navigation function by default. Now if you want to go to specific Fragment, you can show it from backstack.

You can handle it by adding tag in the backStack. Check my answer here :
https://stackoverflow.com/a/19477957/1572408
hope it helps

#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){
// replace your fragment here
return true;
}
return false;
}
});
}
// Happy Coding

If you press back image you have to create method first like this
private void Backpresses() {
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.contant_main, new Home()).commit();
}
then you have to call like this when you press back image..
back.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Backpresses();
}
});
It work fine for me.

Handling ActionBar title with the fragment back stack?

I have an Activity where I load in a ListFragment and, upon clicking, it drills down a level and a new type of ListFragment is shown, replacing the original one (using the showFragment method below). This is placed on the back stack.
At the beginning, the activity shows the default title in the action bar (i.e. it's set automatically based on the application's android:label).
When showing the list for the next level in the hierarchy, the name of the item clicked on should become the action bar's title.
However, when pressing Back, I would like the original default title to be restored. This isn't something FragmentTransaction knows about, so the title isn't restored.
I've vaguely read about FragmentBreadCrumbs, but this seems to require using a custom view. I'm using ActionBarSherlock and would prefer to not have my own custom title view.
What is the best way of doing this? Is it possible without a load of boilerplate code and having to keep track of the titles shown along the way?
protected void showFragment(Fragment f) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.fragment_container, f);
ft.addToBackStack(null);
ft.commit();
}

In every fragment and every activity I change the title like this. This way the active title will always be correct:
#Override
public void onResume() {
super.onResume();
// Set title
getActivity().getActionBar()
.setTitle(R.string.thetitle);
}
There is some cases where onResume isn't called inside fragments. In some of these cases we can use:
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if(isVisibleToUser) {
// Set title
getActivity().getActionBar()
.setTitle(R.string.thetitle);
}
}

As the original answer is quite old, this might come of help as well. As the documentation states, one might want to register a listener to listen on the back stack changes in the hosting Activity:
getSupportFragmentManager().addOnBackStackChangedListener(
new FragmentManager.OnBackStackChangedListener() {
public void onBackStackChanged() {
// Update your UI here.
}
});
Then, identify the situation in the callback method and set a proper title, without accessing the ActionBar from the Fragment.
This is a more elegant solution as the Fragment doesn't have to know about the ActionBar existence and Activity is usually the place that is managing the backstack so having it handled over there seems to be more appropriate. Fragment should at all time be considered only by its own content, not the surroundings.
More on the topic in the documentation.

Let the controlling activity do all the work as follows:
Listen for backstack events (in onCreate() of activity):
// Change the title back when the fragment is changed
getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
Fragment fragment = getFragment();
setTitleFromFragment(fragment);
}
});
Get the current fragment from the container:
/**
* Returns the currently displayed fragment.
* #return
* Fragment or null.
*/
private Fragment getFragment() {
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.container);
return fragment;
}
Set the fragment inside the content view:
private void setFragment(Fragment fragment, boolean addToBackStack) {
// Set the activity title
setTitleFromFragment(fragment);
.
.
.
}

Warpzit is right. This also solves title problem when orientation of device is changed. Also if you use support v7 for action bar, you can get action bar from fragment like this :
#Override
public void onResume() {
super.onResume();
((ActionBarActivity)getActivity()).getSupportActionBar().setTitle("Home");
}

It is best to let the OS do as much of the work as possible.
Assuming each fragment is properly named using .addToBackStack("title") then
you can override onBackPressed something like this to achieve desired behavior:
// this example uses the AppCompat support library
// and works for dynamic fragment titles
#Override
public void onBackPressed() {
FragmentManager fragmentManager = getSupportFragmentManager();
int count = fragmentManager.getBackStackEntryCount();
if (count <= 1) {
finish();
}
else {
String title = fragmentManager.getBackStackEntryAt(count-2).getName();
if (count == 2) {
// here I am using a NavigationDrawer and open it when transitioning to the initial fragment
// a second back-press will result in finish() being called above.
mDrawerLayout.openDrawer(mNavigationDrawerFragment.getView());
}
super.onBackPressed();
Log.v(TAG, "onBackPressed - title="+title);
getSupportActionBar().setTitle(title);
}
}

I use a similar solution to Lee approach, but replacing onBackStackChanged() method instead.
First I set the fragment name when adding the transaction to the back stack.
getSupportFragmentManager().beginTransaction()
.replace(R.id.frame_content, fragment)
.addToBackStack(fragmentTitle)
.commit();
Then I override the onBackStackChanged() method and I call setTitle() with the last backstack entry name.
#Override
public void onBackStackChanged() {
int lastBackStackEntryCount = getSupportFragmentManager().getBackStackEntryCount() - 1;
FragmentManager.BackStackEntry lastBackStackEntry =
getSupportFragmentManager().getBackStackEntryAt(lastBackStackEntryCount);
setTitle(lastBackStackEntry.getName());
}

Use Fragments method:
#Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater)
It is called on every Fragment appearance, but onResume is not.

The best approach is to make use of the android provided Interface OnBackStackChangedListener method onBackStackChanged().
Lets say we have a navigation drawer with 4 options to which the user can navigate to. In that case we will have 4 fragments. Lets see the code first and then I will explain the working.
private int mPreviousBackStackCount = 0;
private String[] title_name = {"Frag1","Frag2","Frag3","Frag4"};
Stack<String> mFragPositionTitleDisplayed;
public class MainActivity extends ActionBarActivity implements FragmentManager.OnBackStackChangedListener
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
....
....
....
getSupportFragmentManager().addOnBackStackChangedListener(this);
mFragPositionTitleDisplayed = new Stack<>();
}
public void displayFragment() {
Fragment fragment = null;
String title = getResources().getString(R.string.app_name);
switch (position) {
case 0:
fragment = new Fragment1();
title = title_name[position];
break;
case 1:
fragment = new Fragment2();
title = title_name[position];
break;
case 2:
fragment = new Fragment3();
title = title_name[position];
break;
case 3:
fragment = new Fragment4();
title = title_name[position];
break;
default:
break;
}
if (fragment != null) {
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container_body, fragment)
.addToBackStack(null)
.commit();
getSupportActionBar().setTitle(title);
}
}
#Override
public void onBackStackChanged() {
int backStackEntryCount = getSupportFragmentManager().getBackStackEntryCount();
if(mPreviousBackStackCount >= backStackEntryCount) {
mFragPositionTitleDisplayed.pop();
if (backStackEntryCount == 0)
getSupportActionBar().setTitle(R.string.app_name);
else if (backStackEntryCount > 0) {
getSupportActionBar().setTitle(mFragPositionTitleDisplayed.peek());
}
mPreviousBackStackCount--;
}
else{
mFragPositionTitleDisplayed.push(title_name[position]);
mPreviousBackStackCount++;
}
}
In the code shown we have the displayFragment() method. Here I display the fragment on the basis of option chosen from the navigation drawer.The variable position corresponds to the position of the item clicked from the ListView or RecyclerView in the navigation drawer. I set the actionbar title accordingly with getSupportActionBar.setTitle(title), where the title stores the appropriate title name.
Whenever we click the item from nav drawer a fragment is displayed depending on the item clicked to the user. But on the back end side this fragment is added to the backstack and the method onBackStachChanged(), gets hit. What I have done is that I have created a variable mPreviousBackStackCount and initialized it to 0. I have also created an additional stack which will store the action bar title names. Whenever I add a new fragment to the backstack, I add the corresponding title name to my created stack. On the opposite side whenever I press the back button onBackStackChanged() is called and I pop the last title name from my stack and set the title to the name derived by the peek() method of the stack.
Example:
Lets say our android backstack is empty:
Press Choice 1 from nav drawer:
onBackStachChanged() is called and the Fragment 1 is added to android backstack, backStackEntryCount is set to 1 and Frag1 is pushed to my stack and size of mFragPositionTitleDisplayed becomes 1.
Press Choice 2 from nav drawer:
onBackStachChanged() is called and the Fragment 2 is added to android backstack, backStackEntryCount is set to 2 and Frag2 is pushed to my stack and size of mFragPositionTitleDisplayed becomes 2.
Now we have 2 elements both in the android stack and my stack. When you press back button onBackStackChanged() is called and the value of backStackEntryCount is 1. The code enters the if part and pops out the last entry from my stack. So, the android backstack has only 1 fragment - "Fragment 1" and my stack has only 1 title - "Frag1". Now I just peek() the title from my stack and set the action bar to that title.
Remember: To set the action bat title use peek() and not pop() else your application will crash when you open more than 2 fragments and try to go back by pressing back button.

You can Solve with onKeyDown!
I have a bool
mainisopen=true <-- MainFragment is Visible
other Fragment mainisopen=false
and here is My Code:
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && mainisopen == false) {
mainisopen = true;
HomeFrag fragment = new HomeFrag();
FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragmet_cont, fragment);
fragmentTransaction.commit();
navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.getMenu().findItem(R.id.nav_home).setChecked(true);
navigationView.setNavigationItemSelectedListener(this);
this.setTitle("Digi - Home"); //Here set the Title back
return true;
} else {
if (keyCode == KeyEvent.KEYCODE_BACK && mainisopen == true) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Wollen sie die App schliessen!");
builder.setCancelable(true);
builder.setPositiveButton("Ja!", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
System.exit(1);
}
});
builder.setNegativeButton("Nein!", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(getApplicationContext(), "Applikation wird fortgesetzt", Toast.LENGTH_SHORT).show();
}
});
AlertDialog dialog = builder.create();
dialog.show();
return true;
}
return super.onKeyDown(keyCode, event);
}
}

As described here my solution is adding this code to MainActivity onCreate method(): and changing actionbar title
FragmentManager fragmentManager=getSupportFragmentManager();
fragmentManager.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
Fragment currentFragment = fragmentManager.findFragmentById(R.id.My_Container_1_ID);
currentFragment.onResume();
}
});
and changing actionbar title in fragment's onResume() method
#Override
public void onResume() {
super.onResume();
AppCompatActivity activity = (AppCompatActivity) getActivity();
ActionBar actionBar = activity.getSupportActionBar();
if(actionBar!=null) {
actionBar.setTitle("Fragment Title");
actionBar.setSubtitle("Subtitle");
}
}

To update the actionbar title on back press. Just simply put
getActivity.setTitle("title")
inside onCreateView method.