I have 2 fragments: (1)Frag1 (2)Frag2.
Frag1
bundl = new Bundle();
bundl.putStringArrayList("elist", eList);
Frag2 dv = new Frag2();
dv.setArguments(bundl);
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.the_fragg,dv);
ft.show(getFragmentManager().findFragmentById(R.id.the_fragg));
ft.addToBackStack(null);
ft.commit();
How do I get this data in Frag2?
Just call getArguments() in your Frag2's onCreateView() method:
public class Frag2 extends Fragment {
public View onCreateView(LayoutInflater inflater,
ViewGroup containerObject,
Bundle savedInstanceState){
//here is your arguments
Bundle bundle=getArguments();
//here is your list array
String[] myStrings=bundle.getStringArray("elist");
}
}
EDIT:
Best practice is read and save arguments in onCreate method. It's worse to do it in onCreateView because onCreateView will be called each time when fragment creates view (for example each time when fragment pops from backstack)
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle arguments = getArguments();
}
Eg: Add data:-
Bundle bundle = new Bundle();
bundle.putString("latitude", latitude);
bundle.putString("longitude", longitude);
bundle.putString("board_id", board_id);
MapFragment mapFragment = new MapFragment();
mapFragment.setArguments(bundle);
Eg: Get data :-
String latitude = getArguments().getString("latitude")
You have a method called getArguments() that belongs to Fragment class.
in Frag1:
Bundle b = new Bundle();
b.putStringArray("arrayname that use to retrive in frag2",StringArrayObject);
Frag2.setArguments(b);
in Frag2:
Bundle b = getArguments();
String[] stringArray = b.getStringArray("arrayname that passed in frag1");
It's that simple.
Instantiating the Fragment the correct way!
getArguments() setArguments() methods seem very useful when it comes
to instantiating a Fragment using a static method.
ie Myfragment.createInstance(String msg)
How to do it?
Fragment code
public MyFragment extends Fragment {
private String displayMsg;
private TextView text;
public static MyFragment createInstance(String displayMsg)
{
MyFragment fragment = new MyFragment();
Bundle args = new Bundle();
args.setString("KEY",displayMsg);
fragment.setArguments(args); //set
return fragment;
}
#Override
public void onCreate(Bundle bundle)
{
displayMsg = getArguments().getString("KEY"): // get
}
#Override
public View onCreateView(LayoutInlater inflater, ViewGroup parent, Bundle bundle){
View view = inflater.inflate(R.id.placeholder,parent,false);
text = (TextView)view.findViewById(R.id.myTextView);
text.setText(displayMsg) // show msg
returm view;
}
}
Let's say you want to pass a String while creating an Instance. This
is how you will do it.
MyFragment.createInstance("This String will be shown in textView");
Read More
1) Why Myfragment.getInstance(String msg) is preferred over new MyFragment(String msg)?
2) Sample code on Fragments
for those like me who are looking to send objects other than primitives,
since you can't create a parameterized constructor in your fragment, just add a setter accessor in your fragment, this always works for me.
If you are using navigation components and navigation graph create a bundle like this
val bundle = bundleOf(KEY to VALUE) // or whatever you would like to create the bundle
then when navigating to the other fragment use this:
findNavController().navigate(
R.id.action_navigate_from_frag1_to_frag2,
bundle
)
and when you land the destination fragment u can access that bundle using
Bundle b = getArguments()// in Java
or
val b = arguments// in kotlin
Related
I have 2 fragments called MedListFragment and MedDetailFragment. In MedListFragment there is a listview with items of Medicine object. When an item is clicked, MedDetailFragment will open with Medicine object passed from MedListFragment.This is the on item click listener in MedListFragment.
MedListFragment
medlist = (ListView) root.findViewById(R.id.medlist);
medlist.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Medicine med = (Medicine) adapterView.getItemAtPosition(i);
FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Bundle bundle = new Bundle();
bundle.putParcelable("medicine", med);
MedDetailFragment medDetailFragment = new MedDetailFragment();
medDetailFragment.setArguments(bundle);
fragmentTransaction.replace(R.id.fragment_container, new MedDetailFragment());
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
Then in MedDetailFragment, I get the bundle like this:
public class MedDetailFragment extends Fragment {
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_med_detail, container, false);
Bundle bundle = getArguments();
Medicine medicine = bundle.getParcelable("medicine");
return root;
}
}
But it returns error on line Medicine medicine = bundle.getParcelable("medicine"); saying:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Parcelable android.os.Bundle.getParcelable(java.lang.String)' on a null object reference
Why are the arguments turn null? How exactly to get the bundle? Any help would be appreciated.
Take a look at these lines
MedDetailFragment medDetailFragment = new MedDetailFragment();
medDetailFragment.setArguments(bundle);
fragmentTransaction.replace(R.id.fragment_container, new MedDetailFragment());
You are creating two different object of MedDetailFragment. And not passing the object in which you have added the bundle.
Change this Line
fragmentTransaction.replace(R.id.fragment_container,medDetailFragment );
you are passing the new object that's why you getting he null
replace the following line
fragmentTransaction.replace(R.id.fragment_container, new MedDetailFragment());
with
fragmentTransaction.replace(R.id.fragment_container, medDetailFragment);
In the lines
MedDetailFragment medDetailFragment = new MedDetailFragment();
medDetailFragment.setArguments(bundle);
You instantiated a MedDetailFragment fragment, and added your arguments.
Thus far all prerequisites were done and medDetailFragment is ready for use.
Now it's time to add it to the placeholder say fragment_container.
But in the line
fragmentTransaction.replace(R.id.fragment_container, new `MedDetailFragment`())
you created a new instance of the fragment once again with the statement new using default constructor that creates a pure instance of MedDetailFragment fragment with no additional data (bundle object).
Obviously calling getArguments() on this instance of the fragment tries to invoke a non-existing part of the fragment causing it to produce java.lang.NullPointerException.
Solution:
In MedListFragment class you have to replece the extra new MedDetailFragment() statement in line
fragmentTransaction.replace(R.id.fragment_container, new MedDetailFragment());
with medDetailFragment you'd created previously.
Optimization:
It's highly recommended to use factory method approach in case of dealing with Fragments. To do so, class MedDetailFragment should look like :
public class MedDetailFragment extends Fragment {
public MedDetailFragment() {
// Required empty public constructor
}
public static MedDetailFragment newInstance(Medicine med) {
Bundle bundle = new Bundle();
bundle.putParcelable("medicine", med);
MedDetailFragment medDetailFragment = new MedDetailFragment();
medDetailFragment.setArguments(bundle);
return medDetailFragment;
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
ViewGroup root = (ViewGroup) inflater.inflate(R.layout.fragment_med_detail, container, false);
Bundle bundle = getArguments();
Medicine medicine = bundle.getParcelable("medicine");
return root;
}
}
and in class MedListFragment you should simply replace the two lines
MedDetailFragment medDetailFragment = new MedDetailFragment();
medDetailFragment.setArguments(bundle);
with just a single line of code:
MedDetailFragment medDetailFragment = MedDetailFragment.newInstance(med);
This approach encapsulates the mechanism within MedDetailFragment class, it's much simpler and easy to debug.
I hope it helps.
I have two fragments: in the first fragment I do it:
ritorno.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v)
{
manager.beginTransaction().replace(R.id.content_frame,new SearchFlight()).addToBackStack(null).commit();
}
});
and this works well. In the second I need to return to the first fragment, so I decide to do this:
String s = element.getText().toString(); //I need to return it
FragmentManager manager = getActivity().getSupportFragmentManager();
SearchFragment fragment = new SearchFragment();
manager.popBackStack();
I need to return to the first fragment this String. How could I do it?
Thanks
There are 3 ways
Static Variable : Define public static variable in first fragment, update its value in second fragment.
BroadcastReceiver
EventBus you can even find EventBus tutorial here
pass string to BR or EventBus and you can fetch it in first fragment by defining appropriate method or listener.
Try doing it with a bundle object.
String s = element.getText().toString(); //item to be returned
FragmentManager manager = getActivity().getSupportFragmentManager();
SearchFragment fragment = new SearchFragment();
Bundle bundle = new Bundle();
bundle.putString("key", "value");
fragment.setArguments(bundle);
manager.popBackStack();
And then, in your SearchFragment resolve the bundle like:
Bundle bundle = this.getArguments();
bundle.getString("key");
Do the resolution part of the bundle in your onCreateView of the SearchFragment. Do place a null check on the resolution part of the bundle. If the bundle is not resolved, then the getString("key") method will give a null pointer exception.
How can I get a value(String) from activity and then use it in Fragment?
errors are occurred
fragment.java
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String strtext = getArguments().getString("edttext");
View rootView = inflater.inflate(R.layout.fragment_user_info,
container, false);
return rootView;
}
activity.java
Bundle bundle = new Bundle();
bundle.putString("edttext", "From Activity");
UserInfoFragment fragobj = new UserInfoFragment();
fragobj.setArguments(bundle);
The error is a NullPointerException, correct?
This is because you read the arguments (in the fragment's constructor):
String strtext = getArguments().getString("edttext");
before you assign them (in activity after the fragment's constructor has already been called):
fragobj.setArguments(bundle);
Keep the constructor simple. Best solution is to create a static factory method newInstance(String edttext) according to this guide https://stackoverflow.com/a/9245510/2444099 like so:
public static UserInfoFragment newInstance(String edttext) {
UserInfoFragment myFragment = new UserInfoFragment();
Bundle args = new Bundle();
args.putInt("edttext", edttext);
myFragment.setArguments(args);
return myFragment;
}
Then use this factory method instead of constructor whenever you need to obtain a new fragment instance.
This is what's happening in your current code:
You create the Fragment
In the onCreateView() method, you get the arguments
You set the arguments in your Activity.
In other words, you're calling the arguments before you've set them. As per the Fragment Documentation, you should be using a static method to instantiate your Fragments. It would look something like the following.
In your Fragment class, add this code
/**
* Create a new instance of UserInfoFragment, initialized to
* show the text in str.
*/
public static MyFragment newInstance(String str) {
MyFragment f = new MyFragment();
// Supply index input as an argument.
Bundle args = new Bundle();
args.putString("edttext", str);
f.setArguments(args);
return f;
}
And now, in your Activity, do the following:
//Bundle bundle = new Bundle();
//bundle.putString("edttext", "From Activity");
//UserInfoFragment fragobj = new UserInfoFragment();
//fragobj.setArguments(bundle);
UserInfoFragment fragobj = UserInfoFragment.newInstance("From Activity");
Notice how now, you don't even need to create a Bundle and set it in your Activity class, it is handled by the static newInstance() method.
I have an enum describing three different sports:
public enum MatchType {
S1(0, "Sport1", "xml stream address", R.id.match_list, R.layout.fragment_match_list, R.color.separator_sport1),
S2(0, "Sport2", "xml stream address", R.id.match_list, R.layout.fragment_match_list, R.color.separator_sport2),
S3(0, "Sport3", "xml stream address", R.id.match_list, R.layout.fragment_match_list, R.color.separator_sport3);
...getters/setters
}
I then have fragment with
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
matchesArrayAdapter = new MatchListAdapter(getActivity(), new ArrayList<Match>());
return inflater.inflate(matchType.getLayout(), container, false);
}
Also in my fragment I have an AsyncTask where I have this
#Override
protected void onPostExecute(final List<Match> matches) {
if (matches != null) {
matchListView = (ListView) getActivity().findViewById(matchType.getRId());
[setup listeners]
matchesArrayAdapter.matchArrayList = matches;
matchListView.setAdapter(matchesArrayAdapter);
}
}
EDIT:
In my Activity I have an AppSectionsPagerAdapter with
public Fragment getItem(int i) {
MatchListSectionFragment fragment = new MatchListSectionFragment();
Bundle bundle = new Bundle();
bundle.putInt(Constants.MATCH_TYPE, i);
fragment.setArguments(bundle);
return fragment;
}
EDIT 2:
Here's my onCreate and onCreateView from my fragment:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle bundle = getArguments();
matchType = MatchType.getMatchType(bundle.getInt(Constants.MATCH_TYPE));
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
matchesArrayAdapter = new MatchListAdapter(getActivity(), new ArrayList<Match>());
return inflater.inflate(matchType.getLayout(), container, false);
}
The AsyncTask reads an xml stream for each of the sports in my enum but my problem is that tab #1 is overwritten with data from tab #2 and subsequently tab #3.
Before I had a fragment defined for each sport but surely that can't be necessary?
How do I go about using the same fragment with the same layout for each sport?
When instantiating your fragment in your Activity set the Fragment's arguments with a Bundle.
Bundle myBundle = new Bundle();
myBundle.putInt(MY_EXTRA, 1);
myFragment.setArguments(myBundle);
In your bundle put some Extra that will be read in the fragment's onCreate() callback.
int i = getArguments().getInt(MY_EXTRA);
I am on mobile.
Put three FrameLayouts in a LinearLayout, named frame1, frame2 and frame 3. This will be your main Activity's layout.
Then in the Activity's oncreate() method, call getFragmentManager().getFragmentTransaction().
Instantiate the three fragments and send them the data, preferably through a Bundle.
On the Fragment Transaction call the add() or replace() method for each fragment, the first parameter is the id of the respective FrameLayout, the second parameter is the fragment itself.
Call commit().
You should create the newInstance method in your fragment, also you should store MatchType instansce in you fragment.
MatchType matchType;
public static MyFragment newInstance(MatchType matchType) {
MyFragment fragment = new MyFragment();
fragment.matchType = matchType;
return fragment;
}
In your Activity you should to create 3 instances of MyFragment with this method (with related to each fragment it owns MatchType). Then in onCreateView method you should insert data to your views from matchType.
Sorry, I'm on mobile. And sorry for my English.
Update
Check your variable matchType. Maybe it declared as static?
I have an Activity which uses a Fragment. I simply want to pass an object from this Activity to the Fragment.
How could I do it?
All the tutorials I've seen so far where retrieving data from resources.
EDIT :
Let's be a bit more precise:
My Activity has a ListView on the left part. When you click on it, the idea is to load a Fragment on the right part.
When I enter this Activity, an Object Category is given through the Intent. This Object contains a List of other Objects Questions (which contains a List of String). These Questions objects are displayed on the ListView.
When I click on one item from the ListView, I want to display the List of String into the Fragment (into a ListView).
To do that, I call the setContentView() from my Activity with a layout. In this layout is defined the Fragment with the correct class to call.
When I call this setContentView(), the onCreateView() of my Fragment is called but at this time, the getArguments() returns null.
How could I manage to have it filled before the call of onCreateView() ?
(tell me if I'm not clear enough)
Thanks
Create a static method in the Fragment and then get it using getArguments().
Example:
public class CommentsFragment extends Fragment {
private static final String DESCRIBABLE_KEY = "describable_key";
private Describable mDescribable;
public static CommentsFragment newInstance(Describable describable) {
CommentsFragment fragment = new CommentsFragment();
Bundle bundle = new Bundle();
bundle.putSerializable(DESCRIBABLE_KEY, describable);
fragment.setArguments(bundle);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
mDescribable = (Describable) getArguments().getSerializable(
DESCRIBABLE_KEY);
// The rest of your code
}
You can afterwards call it from the Activity doing something like:
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
Fragment fragment = CommentsFragment.newInstance(mDescribable);
ft.replace(R.id.comments_fragment, fragment);
ft.commit();
In your activity class:
public class BasicActivity extends Activity {
private ComplexObject co;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_page);
co=new ComplexObject();
getIntent().putExtra("complexObject", co);
FragmentManager fragmentManager = getFragmentManager();
Fragment1 f1 = new Fragment1();
fragmentManager.beginTransaction()
.replace(R.id.frameLayout, f1).commit();
}
Note: Your object should implement Serializable interface
Then in your fragment :
public class Fragment1 extends Fragment {
ComplexObject co;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Intent i = getActivity().getIntent();
co = (ComplexObject) i.getSerializableExtra("complexObject");
View view = inflater.inflate(R.layout.test_page, container, false);
TextView textView = (TextView) view.findViewById(R.id.DENEME);
textView.setText(co.getName());
return view;
}
}
You should create a method within your fragment that accepts the type of object you wish to pass into it. In this case i named it "setObject" (creative huh? :) ) That method can then perform whatever action you need with that object.
MyFragment fragment;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
fragment = new MyFragment();
getSupportFragmentManager().beginTransaction().add(android.R.id.content, detailsFragment)
.commit();
} else {
fragment = (MyFragment) getSupportFragmentManager().findFragmentById(
android.R.id.content);
}
fragment.setObject(yourObject); //create a method like this in your class "MyFragment"
}
Note that i'm using the support library and calls to getSupportFragmentManager() might be just getFragmentManager() for you depending on what you're working with
Get reference from the following example.
1. In fragment:
Create a reference variable for the class whose object you want in the fragment. Simply create a setter method for the reference variable and call the setter before replacing fragment from the activity.
MyEmployee myEmp;
public void setEmployee(MyEmployee myEmp)
{
this.myEmp = myEmp;
}
2. In activity:
//we need to pass object myEmp to fragment myFragment
MyEmployee myEmp = new MyEmployee();
MyFragment myFragment = new MyFragment();
myFragment.setEmployee(myEmp);
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.main_layout, myFragment);
ft.commit();
Passing arguments by bundle is restricted to some data types. But you can transfer any data to your fragment this way:
In your fragment create a public method like this
public void passData(Context context, List<LexItem> list, int pos) {
mContext = context;
mLexItemList = list;
mIndex = pos;
}
and in your activity call passData() with all your needed data types after instantiating the fragment
WebViewFragment myFragment = new WebViewFragment();
myFragment.passData(getApplicationContext(), mLexItemList, index);
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.my_fragment_container, myFragment);
ft.addToBackStack(null);
ft.commit();
Remark: My fragment extends "android.support.v4.app.Fragment", therefore I have to use "getSupportFragmentManager()". Of course, this principle will work also with a fragment class extending "Fragment", but then you have to use "getFragmentManager()".
To pass an object to a fragment, do the following:
First store the objects in Bundle, don't forget to put implements serializable in class.
CategoryRowFragment fragment = new CategoryRowFragment();
// pass arguments to fragment
Bundle bundle = new Bundle();
// event list we want to populate
bundle.putSerializable("eventsList", eventsList);
// the description of the row
bundle.putSerializable("categoryRow", categoryRow);
fragment.setArguments(bundle);
Then retrieve bundles in Fragment
// events that will be populated in this row
mEventsList = (ArrayList<Event>)getArguments().getSerializable("eventsList");
// description of events to be populated in this row
mCategoryRow = (CategoryRow)getArguments().getSerializable("categoryRow");
If the data should survive throughout the application lifecycle and shared among multiple fragments or activities, a Model class might come into consideration, which has got less serialization overhead.
Check this design example
This one worked for me:
In Activity:
User user;
public User getUser(){ return this.user;}
In Fragment's onCreateView method:
User user = ((MainActivity)getActivity()).getUser();
Replace the MainActivity with your Activity Name.