Develop Reference

MapView messed up my fragment transactions?

I have a fragment with a mapview. I can open another fragment (call it listfragment) from the action bar, it works fine. But if I rotate the screen, and then try to open the listfragment, it does not load, instead the mapview flickers on time (the map in the view goes blank and then appears again). If I try to load the listfragment again by clicking the menuitem on the action bar, the app crashes with
java.lang.IllegalStateException: Fragment already added:
Part of MainActivity that loads the fragment:
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mNewTrackFragment = (NewTrackFragment) getFragmentManager()
.findFragmentByTag(TAG_NEW_TRACK_FRAGMENT);
if (mNewTrackFragment == null) {
mNewTrackFragment = NewTrackFragment.newInstance();
}
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.add(R.id.fragment_container, mNewTrackFragment)
.commit();
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_track_list) {
if (null == mTrackListFragment) {
mTrackListFragment = TrackListFragment.newInstance();
}
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.fragment_container, mTrackListFragment, TAG_TRACK_LIST_FRAGMENT)
.addToBackStack(null)
.commit();
return true;
}
Part of NewTrackFragment with the MapView:
public NewTrackFragment() {
}
public static NewTrackFragment newInstance() {
NewTrackFragment fragment = new NewTrackFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_new_track, container, false);
mTrackTitleTV = (TextView) view.findViewById(R.id.tv_track_title);
mDistanceTV = (TextView) view.findViewById(R.id.tv_distance);
mElapsedTimeTV = (TextView) view.findViewById(R.id.tv_elapsed_time);
mSpeedTV = (TextView) view.findViewById(R.id.tv_speed);
mAscentTV = (TextView) view.findViewById(R.id.tv_ascent);
mDescentTV = (TextView) view.findViewById(R.id.tv_descent);
mAltitudeTV = (TextView) view.findViewById(R.id.tv_altitude);
mStartStopFab = (FloatingActionButton) view.findViewById(R.id.fab_startstop);
mMapView = (MapView) view.findViewById(R.id.new_track_mapview);
setupMapView(savedInstanceState);
return view;
}
private void setupMapView(Bundle savedInstanceState) {
mMapView.onCreate(savedInstanceState);
mMapView.getMapAsync(this);
}
I googled the best of the evening for some info about it but found nothing similar.

There's a couple of things wrong here. Right now, you are not passing TAG_NEW_TRACK_FRAGMENT as a tag in the call to add within onCreate. Because of this, you are adding a NewTrackFragment instance without an associated tag, and therefore the call to findFragmentByTag will always return null. Essentially, you are creating a new instance of NewTrackFragment every time you rotate the device. This is not good, because the state of the FragmentManager is preserved across device rotations, meaning it is still holding on to each Fragment you add to it. Because you are unconditionally calling add, the FragmentManager will end up holding multiple instances of NewTrackFragment.
With that said, what you should do is add the tag in the call to add and only call add once you know the FragmentManager is not currently holding on to an instance of NewTrackFragment:
mNewTrackFragment = (NewTrackFragment) getFragmentManager()
.findFragmentByTag(TAG_NEW_TRACK_FRAGMENT);
if (mNewTrackFragment == null) {
mNewTrackFragment = NewTrackFragment.newInstance();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.add(R.id.fragment_container, mNewTrackFragment, TAG_NEW_TRACK_FRAGMENT)
.commit();
}
You might want to do something similar with your TrackListFragment as well:
if (id == R.id.action_track_list) {
FragmentManager fragmentManager = getFragmentManager();
mTrackListFragment = (TrackListFragment) fragmentManager.findFragmentByTag(TAG_TRACK_LIST_FRAGMENT);
if (null == mTrackListFragment) {
mTrackListFragment = TrackListFragment.newInstance();
fragmentManager.beginTransaction()
.replace(R.id.fragment_container, mTrackListFragment, TAG_TRACK_LIST_FRAGMENT)
.addToBackStack(null)
.commit();
}
}

Adding and replacing Fragments , is not working as expected in android

I was trying out android fragments, and i could not understand this; please help
public class MainActivity extends FragmentActivity {
private static final String TAG = "MyActivity";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (findViewById(R.id.fragment_container) !=null) {
if(savedInstanceState!=null){
return ;
}
ArticleFragment first_fragment = new ArticleFragment();
HeadlineFragment second_fragment = new HeadlineFragment();
first_fragment.setArguments(getIntent().getExtras());
second_fragment.setArguments(getIntent().getExtras());
FragmentTransaction manager=getSupportFragmentManager().beginTransaction();
manager.add(R.id.fragment_container, first_fragment,"first");
manager.add(R.id.yo, second_fragment,"second");
manager.commit();
}
}
now i want to remove second_fragment at a button press and replace it with another. So i tried this
if(getSupportFragmentManager().findFragmentByTag("second")!=null) {
Log.d(TAG,"found");
abc newFragment = new abc();
Bundle args = new Bundle();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.remove(getSupportFragmentManager().findFragmentByTag("second"));
transaction.add(R.id.fragment_container,newFragment,"third");
transaction.addToBackStack(null);
transaction.commit();
}
but when i press that button again and again, the if condition passes.
What is wrong here?

Don't Do removing and adding. Simply Replace second fragment with the new one. You will be done.

Cant understand fragment replace

I have trouble understanding in FragmentTransaction.replace(id, fragment, 'string') what does .replace actually
I read somewhere that it will replace the content of view id with fragment but in my
public class MainActivity extends
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (findViewById(R.id.fragment_container) !=null) {
if(savedInstanceState!=null){
return ;
}
ArticleFragment first_fragment = new ArticleFragment();
HeadlineFragment second_fragment = new HeadlineFragment();
first_fragment.setArguments(getIntent().getExtras());
second_fragment.setArguments(getIntent().getExtras());
FragmentTransaction manager=getSupportFragmentManager().beginTransaction();
manager.add(R.id.fragment_container, first_fragment,"first");
manager.add(R.id.fragment_container, second_fragment,"second");
manager.commit();
}
abc newFragment = new abc();
Bundle args = new Bundle();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment_container, newFragment,"second");
transaction.addToBackStack(null);
transaction.commit();
}
}
it only replaces the first fragment that i added to Transaction, i.e. first_fragment.
And how do i replace a specific fragment?

The issue seems to be with R.id.fragment_container. You should have a different first argument on the line below in order to replace a fragment that is not your "first" fragment:
manager.add(R.id.fragment_container, second_fragment,"second");

Android - Dynamic Fragment problems on orientation change

I'm having a problem with dynamic fragment . If I'm not change orientation , it work fine . When I change orientation , I click on ListView item . It's not change textview .
This is DynamicActivity class
public class DynamicActivity extends Activity implements FragmentCoordinator{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dynamic);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
ListContentFragment listContentFragment = new ListContentFragment();
DetailsContentFragment detailsContentFragment = new DetailsContentFragment();
transaction.add(R.id.listContainer, listContentFragment,"listContent");
transaction.add(R.id.detailsContainer, detailsContentFragment,"detailsContent");
transaction.commit();
}
#Override
public void onSetContentDetails(int index) {
FragmentManager fragmentManager = getFragmentManager();
DetailsContentFragment detailsContentFragment = (DetailsContentFragment)fragmentManager.findFragmentByTag("detailsContent");
detailsContentFragment.setContentDetails(index);
}
}
And DetailsContentFragment class
public class DetailsContentFragment extends Fragment {
TextView lbMess;
String[] array;
int saveIndex;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.details_content_fragment, container,false);
array = getResources().getStringArray(R.array.list_details);
lbMess = (TextView)v.findViewById(R.id.lbDetails);
int currentIndex = savedInstanceState == null ? 0 : savedInstanceState.getInt("indexContent",0);
setContentDetails(currentIndex);
return v;
}
#Override
public void onSaveInstanceState(Bundle outState) {
outState.putInt("indexContent", saveIndex);
}
public void setContentDetails(int index) {
saveIndex = index;
lbMess.setText(array[saveIndex]);
}
}
I have debug but it doesn't have any error . Please give me some advice

I found the problems are :
When the system destroys and re-creates an activity because of a run-time configuration change, the activity automatically
re-instantiates existing fragments.
This isn’t a problem for “static” fragments declared in the activity’s layout.
But for “dynamic” fragments, i need to test for this situation to prevent creating a second instance of my fragment.
I check the Bundle argument passed to my activity’s onCreate() is null.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dynamic);
if(savedInstanceState == null)
{
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction transaction = fragmentManager.beginTransaction();
ListContentFragment listContentFragment = new ListContentFragment();
DetailsContentFragment detailsContentFragment = new DetailsContentFragment();
transaction.add(R.id.listContainer, listContentFragment,"listContent");
transaction.add(R.id.detailsContainer, detailsContentFragment,"detailsContent");
transaction.commit();
}
}
And it work fine . I think is helpful for someone have same problems .

Android replace the current fragment with another fragment

I just started with fragment design for HoneyComb. I created two fragments. When i click a button in the left side fragment, a new fragment is created in right side. Meanwhile when i click a button in the right fragment(ie. DetialsFragment in my code below should be replaced by another fragment.
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<fragment class="com.fragment.example.Titles"
android:id="#+id/titles" android:layout_weight="1"
android:layout_width="0px"
android:layout_height="match_parent" />
<FrameLayout android:id="#+id/details" android:layout_weight="1"
android:layout_width="0px"
android:layout_height="match_parent" />
</LinearLayout>
FragmentExample.java
public class FragmentExample extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
Titles.java
public class Titles extends Fragment {
public FragmentTransaction ft;
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.main1, null);
Button button1 = (Button)v.findViewById(R.id.button1);
button1.setText("santhosh");
button1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
DetailsFragment details = (DetailsFragment)
getFragmentManager().findFragmentById(R.id.details);
if (details == null || details.getShownIndex() != 1) {
// Make new fragment to show this selection.
details = DetailsFragment.newInstance(1);
// Execute a transaction, replacing any existing
// fragment with this one inside the frame.
ft
= getFragmentManager().beginTransaction();
ft.add(R.id.details, details, "detail");
ft.setTransition(
FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.commit();
}
}
});
return v;
}
}
DetailsFragment.java
public class DetailsFragment extends Fragment {
/**
* Create a new instance of DetailsFragment, initialized to
* show the text at 'index'.
*/
Titles title = new Titles();
String[] titles = {"Title1", "Title2", "Title3", "Title4"};
public static DetailsFragment newInstance(int index) {
DetailsFragment f = new DetailsFragment();
// Supply index input as an argument.
Bundle args = new Bundle();
args.putInt("index", index);
f.setArguments(args);
return f;
}
public int getShownIndex() {
return getArguments().getInt("index", 0);
}
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
if (container == null) {
// Currently in a layout without a container, so no
// reason to create our view.
return null;
}
Button button = new Button(getActivity());
button.setText("Next");
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
return button;
}
}

Then provided your button is showing and the click event is being fired you can call the following in your click event:
final FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.details, new NewFragmentToReplace(), "NewFragmentTag");
ft.commit();
and if you want to go back to the DetailsFragment on clicking back ensure you add the above transaction to the back stack, i.e.
ft.addToBackStack(null);
Or am I missing something? Alternatively some people suggest that your activity gets the click event for the button and it has responsibility for replacing the fragments in your details pane.

Latest Stuff
Okay. So this is a very old question and has great answers from that time. But a lot has changed since then.
Now, in 2020, if you are working with Kotlin and want to change the fragment then you can do the following.
Add Kotlin extension for Fragments to your project.
In your app level build.gradle file add the following,
dependencies {
def fragment_version = "1.2.5"
// Kotlin
implementation "androidx.fragment:fragment-ktx:$fragment_version"
// Testing Fragments in Isolation
debugImplementation "androidx.fragment:fragment-testing:$fragment_version"
}
Then simple code to replace the fragment,
In your activity
supportFragmentManager.commit {
replace(R.id.frame_layout, YourFragment.newInstance(), "Your_TAG")
addToBackStack(null)
}
References
Check latest version of Fragment extension
More on Fragments

You can try below code. it’s very easy method for push new fragment from old fragment.
private int mContainerId;
private FragmentTransaction fragmentTransaction;
private FragmentManager fragmentManager;
private final static String TAG = "DashBoardActivity";
public void replaceFragment(Fragment fragment, String TAG) {
try {
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(mContainerId, fragment, tag);
fragmentTransaction.addToBackStack(tag);
fragmentTransaction.commitAllowingStateLoss();
} catch (Exception e) {
// TODO: handle exception
}
}

Use android.support.v4.app for FragmentManager & FragmentTransaction in your code, it has worked for me.
DetailsFragment detailsFragment = new DetailsFragment();
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.details,detailsFragment);
fragmentTransaction.commit();

If you have a handle to an existing fragment you can just replace it with the fragment's ID.
Example in Kotlin:
fun aTestFuction() {
val existingFragment = MyExistingFragment() //Get it from somewhere, this is a dirty example
val newFragment = MyNewFragment()
replaceFragment(existingFragment, newFragment, "myTag")
}
fun replaceFragment(existing: Fragment, new: Fragment, tag: String? = null) {
supportFragmentManager.beginTransaction().replace(existing.id, new, tag).commit()
}

Updated Answer (Working for Overlap problem as well)
#aniket-thakur(https://stackoverflow.com/users/2396539/aniket-thakur) gave correct answer. Thank you for that!
But, getFragmentManager() is deprecated, so following code did work for me.
final FragmentTransaction ft = getParentFragmentManager().beginTransaction();
ft.replace(R.id.nav_host_fragment, new GalleryFragment(), "NewFragmentTag");
ft.addToBackStack(null);
ft.commit();

it's very simple how to replace with Fragment.
DataFromDb changeActivity = new DataFromDb();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.changeFrg, changeActivity);
transaction.commit();