Develop Reference

Move from one Fragment inside Activity to another Fragment inside Activity

So I have Activity A with Fragment A.1, and I also have Activity B with Fragment B.1.
What I want to ask is, how do I move directly from Fragment A.1 to Fragment B.1?
I know to move from Fragment A.1 to Activity B, is by:
Intent i = new Intent (getActivity (), MainActivity.class);
startActivity (i);
getActivity ().finish();
But how to move straight to Fragment B.1?
Each Activity A and Activity B has a different <FrameLayout> for Fragment replacement
UPDATE 1.0
I've tried my own way and also the way #cewaphi answered with code like this,
In Activity A:
Intent i = new Intent(TransactionDone.this, MainActivity.class);
i.putExtra("immediatelyTransactionToFragment", true);
startActivity(i);
finishAffinity();
In Activity B:
boolean shouldTransitionToFragment = getIntent().getBooleanExtra("immediatelyTransationToFragment", true);
if (shouldTransitionToFragment) {
Fragment fragment = new Wallet();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.mainFrameLayout, fragment);
transaction.commit();
Log.d("DEBUGGING REDIRECT", "Go to Fragment B.1");
}
The log "Go to Fragment B.1" was created but the transaction doesn't work

When using a single activity and e.g. using the navigation component is not an option.
Consider the following:
In your fragment A.1 when starting the activity store a Boolean
i.putExtra("immediatelyTransationToFragment", true);
In activity B
shouldTransitionToFragment = getIntent().getBooleanExtra("immediatelyTransationToFragment");
// after activity was created
if (shouldTransitionToFragment) {
// Execute the transition action as you would when pressing the button
}
Update 2020/09/07
You are trying to transition to a Fragment from your Activity like this:
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.mainFrameLayout, fragment);
transaction.commit();
The documentation states that you should first add the fragment to the activity:
ExampleFragment fragment = new ExampleFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();
Apparently your transition works when you click your button. Are you doing it the same?
But I assume at that time the activity has already been created.
Try once to add your fragment instead of replace. I don't know how your container is initialised but adding might be the operation you want, I refer to this good answer for clarification.
Also consider to perform to call this transaction after your activity was created.

Android Back to previous fragment by popBackStack

I have 3 fragments: Home, A and B. Home and A are in mobile navigation menu.
User goes from A to B and then press back button. The issue that if I use getFragmentManager().popBackStack(); onCreateView of fragment A is calling and I have duplicating of content.
But if I use getActivity().onBackPressed(); it goes to Home fragment instead of A.
How to display fragment A by clicking back button without refreshing the view?
Here is how I make transaction from A to B
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(null);
fragmentTransaction.commit();

You need to know some premise before using FragmentManager.
in Activity there is FragmentManager and we should call it with getSupportFragmentManager(), getFragmentManager() is deprecated.
in Fragment there are multiple FragmentManagers called ParentFragmentManager and ChildFragmentManager, the final FragmentManager which is deprecated too. And ParentFragmentManager will be same as Activity's FragmentManager
getActivity().onBackPressed() will pull out fragment if any stack exists in Activity's FragmentManager
fragmentManager.popBackStack() will pull out fragment if any stack exists in Activity's or Fragment's FragmentManager rely on who calls
Base on above points
(1) If You want to hold fragments in Activity, you should call getSupportFragmentManager() in Activity, and call getParentManager() in Fragment, then onBackPressed() will pull out the fragment you last add to stack.
(2) If you want to hold fragments in a Fragment and Separated from Activity, you should call getChildFragmentManager() in Fragment, then activity.onBackPressed() will pull out the fragment which in Activity's fragment stack and ignore other fragments in Fragment's fragment stack.
For question will be same as case (1), and if you dont want re-create fragment, you should use add() instead of replace()
in Fragment A
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getParentFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(CertificateItemFragment.TAG);
fragmentTransaction.commit();
now onBackPressed() will backstack from CertificateItemFragment to Pre-Fragment

In normal case navigation item list menu open fragment which are replace to each other but when we move inside of any item as like in your case move from fragment A to B,
In this case normally we use another activity on which create fragment.
If you do't want to use activity then, you just need to add fragment.
try below code that may help you
CertificateItemFragment certificateItemFragment = new CertificateItemFragment(item);
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.nav_host_fragment, certificateItemFragment).addToBackStack(CertificateItemFragment.TAG);
fragmentTransaction.commit();

Start Fragment via function in MainActivity

I'm trying to start a fragment programmatically. The function below works fine on its own. The problem here is, that I have to call the function from within another fragment. The call from the fragment to MainActivity works and is not the problem.
public void gotoFragment1(){
Fragment1 fragment = new Fragment1();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.nav_host_fragment, fragment);
transaction.addToBackStack(null);
transaction.commit();
}
If I try to call the function from another fragment the app crashes with the following stacktrace:
java.lang.IllegalStateException: FragmentManager has not been attached to a host.
at androidx.fragment.app.FragmentManager.enqueueAction(FragmentManager.java:1727)
at androidx.fragment.app.BackStackRecord.commitInternal(BackStackRecord.java:321)
at androidx.fragment.app.BackStackRecord.commit(BackStackRecord.java:286)
at com.fewo.info.MainActivity.gotoVeranstaltungen(MainActivity.java:134)
at com.fewo.info.ui.home.HomeFragment$1.onClick(HomeFragment.java:53)
How can I change the fragment with this code beeing called from within another fragment?

if you want replace a fragment in MainActivity from other Fragments, you can do it in your fragment (No need to call function from MainActivity),
use this in your fragment:
getFragmentManager().beginTransaction()
.replace(R.id.nav_host_fragment, new Fragment1(), FragmentLoanList.class.getName()).addToBackStack(null)
.commit();

Fragment A:
((ActivityOne) getActivity()).callFragmentB();
Activity One
public void callFragmentB(){
//run your fragment transaction To B here
}

Calling fragment inside MainActivitySo

I have implemented navigation drawer in my app. When I open the app first it shows blank screen. Instead I want it to start fragmentA.
I have tried
Intent i = new Intent(MainActivity.this, fragmentA.class);
startActivity(i);
but this gives me activity not found exception.
So how can I start a fragment inside an activity?

Try:
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.yourFrame, fragmentA.getInstance());
fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
fragmentTransaction.commit();
in your activity

How to start a Fragment/Activity within Fragment?

I have a button in Fragment. When Button is clicked it has to Open new Fragment/Activity within Fragment. I have written code using Intent,
Intent i = new Intent();
i.setClass(getActivity(), UpdateProfile.class);
startActivity(i);
but its opening in new activity like in below image.
My requirement is in Picture 1. Can someone suggest me how to do it?
EDIT: As suggested by rai and ADK, its working fine but new fragment overlays on old fragment. See the below image. "Change Password"(TextView) is New Fragment which overlays on existing fragment.

Try:
getFragmentManager()
.beginTransaction()
.replace(containerViewId, newFragment)
.addToBackStack(null) // enables back key
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE) // if you need transition
.commit();

You should to use FragmentTransaction enter link description here.
Like this
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.yourFragment, YourFragmentWithImageClass.getInstance());
fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
fragmentTransaction.commit();
in your Activity