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Handle onBackPressed in android in fragment

I want to handle onBackPressed in fragment
I use following code in my activity but this return 0
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
Toast.makeText(getBaseContext(), ""+count, Toast.LENGTH_SHORT).show();
if (count == 1) {
super.onBackPressed();
//additional code
} else {
getFragmentManager().popBackStack();
}
}

Just add .addToBackStack(null) in your Activity or Fragment . When you adding or replacing fragment. Like below
getSupportFragmentManager().beginTransaction().replace(R.id.parent_layout, new MyFragment()).addToBackStack(null).commit();
Note:- you don't have to do anything in your onBackPressed() method.

Just app this line when you want to replace any fragment and manage backsack on Fragment.
ClientHome per = new ClientHome();
Bundle bundle = new Bundle();
bundle.putString("usertype", "client");
per.setArguments(bundle);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.setCustomAnimations(R.anim.slide_from_left, R.anim.slide_to_right);
fragmentTransaction.replace(R.id.content_frame, per, "tag");
fragmentTransaction.addToBackStack("tag");
fragmentTransaction.commit();

How to transfer data from fragment to fragment through Bundle

Below is the adapter code of first fragment , here and sending data to second fragment StoreDetails.
holder.cv.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
StoreDetails fragment = new StoreDetails();
Bundle bundle = new Bundle();
bundle.putString("store_id",pojo.getSTORE_ID());
bundle.putString("store_name",pojo.getSTORE_NAME());
bundle.putString("address",pojo.getSTORE_ADDRESS());
// bundle.putString("status",pojo.getSTATUS());
// bundle.putString("teammember",pojo.getSTATUS());
fragment.setArguments(bundle);
FragmentManager manager=fragment.getFragmentManager();
// in below line I am getting error
FragmentTransaction ft = manager.beginTransaction().replace(R.id.container,fragment,"fragment");
ft.addToBackStack("fragment");
ft.commit();
}
});
Below is the StoreDetails fragment
Bundle bundle = getArguments();
mstore_id = bundle.getString("store_id");
mstore_name =bundle.getString("store_name");
mstoreaddress= bundle.getString("address");
mstorestatus = bundle.getString("status");
mteammember = bundle.getString("teammember");
The error I'm receiving is
java.lang.NullPointerException: Attempt to invoke virtual method
'android.app.FragmentTransaction
android.app.FragmentManager.beginTransaction()' on a null object
reference at Adapter.Tab1_Adapter$1.onClick(Tab1_Adapter.java:78)

FragmentManager will be null until it is attached to the activity.
instead of using
FragmentManager manager=fragment.getFragmentManager();
use
getActivity().getFragmentManager() or getActivity().getSupportFragmentManager();

What is the best way to add fragment in the Tabs android

My application had a bottom navigation bar which has 5 tabs.
So according to these tabs, I have 5 fragments
When I click on the tab, the fragment changed according to that tab.
I can switch fragment by using the method beginTransaction().replace...
I dont want the fragment to be destroyed and recreated again each time I switch tabs, so my solution is sth like this
//I init 5 fragments
Fragment1 frag1 = new Fragment1();
Fragment2 frag2 = new Fragment2();
Fragment3 frag3 = new Fragment3();
Fragment4 frag4 = new Fragment4();
Fragment5 frag5 = new Fragment5();
//When I click on tab, for example tab1, I hide all fragments except tab1
//hide all fragments
getSupportFragmentManager()
.beginTransaction()
.hide(fragment1) //Fragment2, 3, 4, 5 as well
.commit();
//show fragment 1
getSupportFragmentManager()
.beginTransaction()
.show(fragment1)
.commit();
It works very well, but the problem is sometimes 2 fragments show at once time (I dont know why because I hide all fragments)
Any other way to achieve that? Switch fragment without destroying it and creating it again.

for adding fragment I make this code for my project, hope it will be help.
public static void replaceFragment(Fragment fragment, FragmentManager fragmentManager) {
String backStateName = fragment.getClass().getName();
String fragmentTag = backStateName;
Fragment currentFrag = fragmentManager.findFragmentById(R.id.frame_container);
Log.e("Current Fragment", "" + currentFrag);
// boolean fragmentPopped = fragmentManager.popBackStackImmediate(backStateName, 0);
int countFrag = fragmentManager.getBackStackEntryCount();
Log.e("Count", "" + countFrag);
if (currentFrag != null && currentFrag.getClass().getName().equalsIgnoreCase(fragment.getClass().getName())) {
return;
}
FragmentTransaction ft = fragmentManager.beginTransaction();
// if (!fragmentPopped) {
ft.replace(R.id.frame_container, fragment);
ft.addToBackStack(backStateName);
ft.commit();
// }
currentFrag = fragmentManager.findFragmentById(R.id.frame_container);
Log.e("Current Fragment", "" + currentFrag);
}
hope this will be help you, and use this method in entire project for replacing fragment.

Using ViewPager with FragmentPagerAdapter suits for you in this case.
Then use ViewPager#setOffsetPageLimit(5). This will help you show/hide your fragments without recreating it again.
Follow this tutorial
Let try it, then tell me if your problem is solved or not. ;)

you don't have to need to hide the fragment just replace the fragment like this method:
public void setFragment(Fragment fragmentWhichYouWantToShow) {
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
ft.replace(R.id.container, fragmentWhichYouWantToShow);
ft.commit();
}

Try to make it in a singe transaction.
protected void showAsRootFragment(Fragment fragment, #NonNull String tag) {
FragmentManager supportFragmentManager = getSupportFragmentManager();
FragmentTransaction transaction = supportFragmentManager.beginTransaction();
if (supportFragmentManager.getFragments() != null) {
for (Fragment attachedFragment : supportFragmentManager.getFragments()) {
if (attachedFragment != null && !tag.equals(attachedFragment.getTag())) {
transaction.hide(attachedFragment);
attachedFragment.setUserVisibleHint(false);
}
}
}
if (!fragment.isAdded()) {
transaction.add(R.id.frame_container, fragment, tag);
fragment.setUserVisibleHint(true);
} else {
transaction.show(fragment);
fragment.setUserVisibleHint(true);
}
transaction.commit();
}

Fragment UX choice and genericity

I find myself switching between a lot of Fragments in my card game app.
When my user creates a deck he goes through the following fragments:
Deck List Fragment (Click on 'New Deck') -> Class Selection Fragment (Mage, Warrior etc.) -> Name Selection Fragment -> Back to Deck List Fragment with our new deck listed.
I do this in order to have a smooth deck creation process but here are my two questions:
1) Is it recommended to use more Fragments than required if it makes the UX better and smoother?
2) Note that I do the following in order to switch Fragment:
Fragment fragment = new MyFragment();
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
// Set argument(s) - Not all fragments set arguments
Bundle args = new Bundle();
args.putString("deckName", deckName);
fragment.setArguments(args);
fragmentTransaction.replace(R.id.content_frame, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
Instead of having similar methods from one Fragment to the other, I wish to create a generic method that takes a variable amount of parameters and the type of Fragment to create and switches to said Fragment.
But I can't seem to figure out how to do it.
Please excuse this lengthy post, and thank you.

Check out my code :
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
replaceFragment(new HomeFragment());
}
public void replaceFragment(final Fragment fragment) {
getFragmentManager()
.beginTransaction()
.replace(R.id.container, fragment, fragment.getClass().getSimpleName())
.commit();
}
public void addFragment(final Fragment fragment) {
final Fragment hideFragment = getFragmentManager().findFragmentById(R.id.container);
getFragmentManager()
.beginTransaction()
.add(R.id.container, fragment, fragment.getClass().getSimpleName())
.hide(hideFragment)
.addToBackStack(hideFragment.getClass().getSimpleName())
.commit();
}
}
Call above methods in Fragment :
final HomeFragment homeFragment = new HomeFragment();
final Bundle bundle = new Bundle();
bundle.putString("KEY","VALUE");
homeFragment.setArguments(bundle);
((MainActivity) getActivity()).addFragment(homeFragment);

What's wrong with the code below?

I'm learning from the book from big nerd ranch.
FragmentManager fm = getFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragmentContainer);
if (fragment == null) {
fragment = new CrimeFragment();
fm.beginTransaction().add(R.id.fragmentContainer, fragment).commit();
}
Got a type mismatch error.
However, if I call
CrimeFragment fragment = fm.findFragmentById(R.id.fragmentContainer);
it will not work. So my question is how to call a CustomFragment(CrimeFragment) using an id from the layout?
Thanks in advance.

I usually do it like this:
CrimeFragment fragment = new CrimeFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragmentContainer, fragment).commit();
or
transaction.add(R.id.fragmentContainer, fragment).commit();
More information:
The screen orientation change will cause the fragment update once more if it is create in onCreate method.
you can prevent this here:
if (savedInstanceState == null){
CrimeFragment fragment = new CrimeFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragmentContainer, fragment, "fragment").commit();
}else{
CrimeFragment homeFragment = (CrimeFragment) getSupportFragmentManager().findFragmentByTag("fragment");
}