So I have a class which has a tabbed layout of 4 fragments each with a list of checkboxes. I need to save the state of those checkboxes in a sqlite database, but I am not able to access them at all with findViewById from the activity (throws a nullpointerexception). How would I go about doing this? Thanks!
When you first add or replace any fragment.. add a tag for it.. then later use this is acticity
fragment f1 = getfragmentmanager.findfragmentByTag("tag1");
then you can get and save
f1.getCheckbox1().ischecked()...
amd so on...
you can use getFragmentManager.getFragments...
You can't access view elements in your fragment from your activity, it simply wasn't created for this. And why would you need to?
You can simply save the values of your checkboxes inside your fragment code, where you have full access to the entire view. You can still access your sqlite database inside a fragment, it doesn't have to be an activity.
In a fragment you can override the onCreateView and inflate the view.
http://developer.android.com/training/basics/fragments/creating.html
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.article_view, container, false);
TextView textView = (TextView) v.findViewById(R.id.testelement);
return v;
}
And find the elements by doing this.
Related
This confuses me a lot.
I had two fragments, and I use FragmentTransaction.replace() the swap the two fragments. State of some input controls like RadioGroup and checkbox is always preserved when I switch to the other fragments and switch back again.
.
I set break point on my OnCreateView() of Fragment, and every swap seems to trigger the method and new views are created each time. The savedInstanceBundle is always null as well. Since the new views are created, how do they get the state of the old views?
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_fieldsetup_marking, container, false);
// ...
return v;
}
This effect is fine for my app, but I just want to know how it is implemented.
where are the states stored?
Where is the android SDK code to restore this (I can not find any in the class FragmentTransection).
i'm reading this android dev book and im stuck understanding how this line of code is error free (please keep in mind i've gotten rid of some code because for more focus on this part.
public View onCreateView(LayoutInflater layoutToInflate, ViewGroup parent, Bundle saveState)
{
View v = layoutToInflate.inflate(R.layout.activity_main_fragment,parent,false);
return v;
}
from what i believe, i need a method that returns a view because the Class extends from a Fragment class, not an activity so i have to explicitly find the view, the parameters are straight forward what i dont understand is how we create a view and set it equal to layoutToInflate...false;
I think you have a misunderstanding what the concepts of Fragments are. They reside inside an Activity. If a Fragment has a UI, it needs the parent Activity to also have a UI. That also means Fragments have a ViewParentbelonging to an Activity. This parent is given to the Fragment by the ViewGroup parent argument. So when creating a Fragment with a UI, you need to inflate the layout belonging to your Fragment and pass it to the Activity, which adds it to the ViewGroup parent. So that's why you get a LayoutInflater to inflate your Fragment's view:
View v = layoutToInflate.inflate(R.layout.activity_main_fragment,parent,false);
Afterwards you return it to give it to the parent Activity.
layoutToInflate is a variable of LayoutInflater and R.layout.activity_main_fragment is the name of the layout file to be inflated.
I'm building an android app in which I use one Activity from which I can load several fragments. So I start with the FragmentA, and from that I load Fragment B as follows:
FragmentTransaction tx = getSupportFragmentManager().beginTransaction();
tx.replace(R.id.content_frame, detailsFragment).addToBackStack(null).commit();
This works fine. When I press the backbutton, it also goes back to FragmentA perfectly well. The problem is that when I click on the button to go to FragmentB again I get an InflateException (Duplicate id 0x7f08007a, tag null, or parent id 0x0 with another fragment for com.ourcomp.fragment.DetailsFragment) on this line:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_details, null);
}
I think I need to check whether it was inflated already, but I don't really know how. Does anybody know how I can check wether the view was already inflated so that I can prevent this error?
After checking documentation again, I found:
The ViewGroup to be the parent of the inflated layout. Passing the container is important in order for the system to apply layout parameters to the root view of the inflated layout, specified by the parent view in which it's going.
So try to replace
return inflater.inflate(R.layout.fragment_details, null);
with
return inflater.inflate(R.layout.fragment_details, container);
this is bit when i'm creating view,
public static int a=0;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
a++;
View view = inflater.inflate(R.layout.fragment_layout, container, false);
editText = (EditText) view.findViewById(R.id.amount);
TextView tv = (TextView) view.findViewById(R.id.textView1);
Button button = (Button) view.findViewById(R.id.addTransaction);
button.setOnClickListener(this); ///fragments implements OnClickListener
editText.setText(""+a);
tv.setText(""+a);
return view;
}
when i load this fragment first time, my editText is empty, but when i load fragment again, value in the editText is same like in previous execution.
Is anyone has idea what i'm doing wrong? And how i can fix it?
** EDIT
i modified little bit my code, now each time when i'm loading fragment a is incremented. and io noticed weird behaviour. tv has has actual value of a, while editText still has old value
You need to move the settext ( and probably some other stuff) into a later method in the fragment life cycle e.g. onActivityCreated.
Before adding the fragment try to get the fragment by calling FindFragmentByTag("tag"), i think you are adding new fragments on top of each other. Also add your fragment transaction to back state and then to check if more than one fragments are added, press back button. I had similar problem, and the reason was i kept adding new fragments in activity
Fragments are tied to activities, so my guess is that the activity is not being destroyed, which means your fragment is not being destroyed and instead "resumed". Perhaps you want that code in the onResume callback? Take a look at the Fragment lifecycle: Android Fragments
Im making an App. And I want to access my 3 main activities into 3 different fragments. i use viewpager to swap activities but it only show layouts do not work on its functionality. Then i used Fragment to use functions. but my problem is same its only show layouts not is functions.
i made 3 different fragment for 3 activities and use
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.settings, container, false);
return v;
}
method.
idont know how to use onActivityCreated() method or getActivity(). please help me..
i search all of it about it but cannot done yet.. :(
To access Widget Of layout just use this
View.findViewById();