I have android screen layout shown below
Apps screen divided into 3 fragments, Header, Footer and Content. Header and Footer fragments are fixed. Content fragment is changing according to content. I replaces fragment1-fragment3 according to need. Initially Fragment1 is shows in content area. When i press a next button fragment1 is replace by fragment2. This is the order. I have question, if i press another button previous, how can i return to previous fragment ( fragment2 -> fragment1). Is any built in mechanism available in fragment class.
Please guide me...
thanks in advance
try this code
FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();
Whenever you try to call new fragment then add back stack for it through
ft.addToBackStack(null);
And now if you want to back from one fragment to another then, make one method..
public void DeleteCurrentFragment()
{
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
Fragment currentFrag = getSupportFragmentManager().findFragmentById(R.id.detailFragment);
String fragName = "NONE";
if (currentFrag!=null)
fragName = currentFrag.getClass().getSimpleName();
if (currentFrag != null)
transaction.remove(currentFrag);
transaction.commit();
}
And after that call this:
getSupportFragmentManager().popBackStack();
DeleteCurrentFragment();
you can try something like:
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction ft = manager.beginTransaction();
ft.add(R.id.contentFragment, <your fragment>);
ft.addToBackStack(null);
ft.commit();
so suppose you're on fragment1 and after doing some stuff you want push fragment2 then on your contentFragment you can add or replace the fragment (fragment2 in this case) as per your requirement. Now when you call addToBackStack it means add this transaction to the back stack. So that the transaction will be remembered after it is committed, and will reverse its operation when later popped off the stack. Internally it maintains a stack so you don't want to do anything. At last when you press back button from fragment2 it checks whether the transaction having any fragment in its stack, if yes then it calls it. Its like top of stack. When you call addToBackStack in that stack fragment1 is added. So when you press back button stack's top is fragment1 so it calls it.
It happens when you press hardware back button. If you want to do this on any button, then on that button's click listener simply onBackPressed() method.
Related
I wanted to know how I can get the Fragment which is onloaded on my Acticvity.
The background behind this is, that I want to change the onBackPressed method that it's switching to the right fragments. At the moment when I press "Back" the app closes, because I work alot with fragments.
Use addToBackStack on your fragment transaction. This way when you press the back key the transaction gets rolled back and thus your fragment disappears.
I got a solution for the problem:
Fragment fragment = new Fragment();
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = manager.beginTransaction();
fragmentTransaction.add(R.id.Layout,Fragment);
fragmentTransaction.addToBackStack("flow1");
fragmentTransaction.commit();
Working with fragments I've always used replace() for my transactions, but I wish I didn't have to save instance states anymore to restore a fragment's view and prevent reloading when coming back to that fragment. So, I've decided to work with add(). The thing is when I add another fragment, the previous fragment view remains in the background and that's fine (that's the behavior I expected), but the problem is I can actually interact with the views in the background. Example:
Fragment A has a Button
Fragment B has a TextView
When I add Fragment A and later add Fragment B, I'm able to click on Fragment A's Button, even staying on Fragment B's view.
I'm using:
FragmentTransaction fragmentTransaction =
getSupportFragmentManager().beginTransaction().
add(getRootViewContainer(),fragment,fragment.getClass().getSimpleName());
if (shouldGoBack)
fragmentTransaction.addToBackStack(fragment.getClass().getSimpleName());
where getRootViewContainer() returns the id of the FrameLayout I'm using as my activity main container.
Now, is it really the default behavior of add()?
If so, is there a proper way to avoid this or one just has to use replace()?
What you can do here is just hide previous fragment at the time of transaction of current fragment.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Fragment newFragment= new MyFragment ();
ft.hide(CurrentFragment.this);
ft.show(newFragment);
ft.commit();
It worked for me just try it.
FragmentTransaction.hide(fragmentBehind); //works for me!
example :
//I have it globally available
FragmentTransaction trans = MainActivity.getManager().beginTransaction();
//not globally
FragmentTransaction trans = getFragmentManager().beginTransaction();
MapFragment newFragment = new newFragment();
trans.add(R.id.fragmentContainer, newFragment, tag);
trans.hide(this);
trans.addToBackStack(tag);
trans.commit();
Yes, this is a default behaviour of add().
If you really don't want to user replace(), you can try to disable views which are inside "old" fragment.
I have a form divided in few fragments. I call every fragment with:
final FragmentManager fm = getSupportFragmentManager();
final FragmentTransaction ft = fm.beginTransaction();
if(fragment.equals(this.formOne) || fragment.equals(this.formTwo)) {
ft.setCustomAnimations(android.R.anim.slide_in_left,android.R.anim.slide_out_right);
}
ft.replace(R.id.fragForm, fragment);
ft.addToBackStack(null);
ft.commit();
When I click on the back button it skips the previous Fragment and goes back to the Activity but with a blank screen.
For example, I have 3 fragments : A - B - C
If I go to C and want to go back to the previous Activity, I click on the back button so I'm on B, I click again and I'm on A, and when I click again, I have a blank screen, I need to click another time to come back to the previous activity.
I don't understand why have I this blank screen on my Activity.
I don't understand this in the developer documentation:
Note: You should not add transactions to the back stack when the
transaction is for horizontal navigation (such as when switching tabs)
or when modifying the content appearance (such as when adjusting
filters). For more information, about when Back navigation is
appropriate, see the Navigation design guide.
If we can't use that, what is the solution?
Don't add it to the backstack when you add fragment A.
ft.add(R.id.fragForm, fragmentA);
ft.commit();
ft.replace(R.id.fragForm, fragmentB);
ft.addToBackStack(null);
ft.commit();
ft.replace(R.id.fragForm, fragmentC);
ft.addToBackStack(null);
ft.commit();
If you don't have to Navigate to previous fragment don't add it to the backstack
Remove this
ft.addToBackStack(null);
I have an app that uses fragments with tabs/viewpager
[Tab 1][Tab 2][Tab 3]
Tab2 has a ListView and in the onClick method of the ListView I am showing a detail view with the following code
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
NextFragment nextFragment = new NextFragment();
transaction.replace(R.id.container, nextFragment);
transaction.addToBackStack(null);
transaction.commit();
The issue is that in the NextFragment when I use the hardware back button the whole app closes?
I'm not sure why it doesn't let you return when back is pressed, but what I've done in my application is the following:
I have overriden the onBackPressed action and created a check that once it is pressed and the user is in the fragment that he wants to return from, just create another fragment transaction to the previous fragment.
I have done so because I needed to update the previous fragment, but I'm sure there is a better way to solve your problem.
I created a sample app to test this overlapping issue.
I have a fragment type, Fragment1, and I create a new instance of Fragment1 and add it to a FrameLayout in my activity at runtime. I add the fragment with the help of a few buttons.
Note: I have given each new instance of Fragment1 a different number(#1, #2, #3, etc.) to display on the UI to help me figure out which fragment I am viewing.
So.. here is what I do:
Click on Button 3, create new instance of Fragment1 and add it to Frame1.
Click on Button 4, create new instance of Fragment1 and add it to Frame1 and add it to the fragment backstack.
Repeat 1 and 2.
Repeat 1 and 2.
Now, I have fragments in this order: 1(#1),2(#2),1(#3),2(#4),1(#5),2(#6).
I press the back key when viewing fragment #6.
Back key press, UI displays (#5).
Back key press, UI displays (#3 AND #5),
Back key press, UI displays (#1, #3, AND #5)
It seems fragments are getting displayed ON TOP of each other.
WHY? Is there an overlapping issue? How can I clear out this overlapping issue. I thought this would be an issue on the compatibility library... but it is also on 3.0.
Code for adding fragments:
public int doFragmentChange(int cont1, Fragment frag1, String tag1, int cont2, Fragment frag2, String tag2,
boolean addToStack, String stackTag) {
FragmentManager fm = getFragmentManager();// getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
if (frag1 != null) {
ft.replace(cont1, frag1, tag1);
}
if (frag2 != null) {
ft.replace(cont2, frag2, tag2);
}
// add fragment to stack
if (addToStack)
ft.addToBackStack(stackTag);
return ft.commit();
}
If you perform two add calls one after the other (two commit calls) then yes the fragments will appear overlaid, one on top of the other effectively.
So (for new example) if say you replace frag1 with frag2 and then frag3 with frag4 in the same frame with no backstack transaction then I would expect frag2 and frag4 to be overlaid.
Furtheremore there is also a potential issue in your chaining of replace. You should call a separate commit for each. See Android — Replace Fragment Back Stack With New Stack?.
Just override the onBackPress() or onKeyUp and remove the top fragment.