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.
Related
So the problem is not a technical issue, but more of an aesthetic kind.
I am passing data from one fragment to another fragment. So there are 3 fragments in total and the first two are calling the same 3rd fragment, so to identify in the third fragment from which of the first two it was invoked I am using the following code
in the first fragment
Bundle bundle = new Bundle();
bundle.putBoolean("isFirst", true)
Fragment fragment = new ThirdFragment();
fragment.setArguments(bundle);
loadFragment(fragment);
and in the second fragment as
Bundle bundle = new Bundle();
bundle.putBoolean("isFirst", false)
Fragment fragment = new ThirdFragment();
fragment.setArguments(bundle);
loadFragment(fragment);
and in the third fragment
Bundle bundle = this.getArguments();
Boolean isFirst = bundle.getBoolean("isFirst",false);
if(isFirst){
....
} else{
....
}
the code works fine but I think there should be a more elegant way of doing it. If not atleast make the whole thing into one line without additional declarations such as Bundle bundle and Fragment fragment
for example something like
loadFragment(new ThirdFragment().setArguments(new Bundle().putBoolean("isFirst",true)));
I am relatively new to android and java programming so please don't be harsh.
I think you should declare static method getInstance(Boolean isFirst) in ThirdFragment example
public static ThirdFragment getInstance(Boolean isFirst) {
Bundle bundle = new Bundle();
bundle.putBoolean("isFirst", isFirst)
Fragment fragment = new ThirdFragment();
fragment.setArguments(bundle);
return fragment
}
In First and SecondFragment call
loadFragment(ThirdFragment.getInstance(true));
you can create newIstance() in ThirdFragment like stated here
you can also achieve the same by the below code
public class Util {
static Fragment getThirdFragment(FragmentManager fragmentManager, Boolean isFirst, #NonNull ClassLoader classLoader, #NonNull String className) {
Bundle bundle = new Bundle();
bundle.putBoolean("isFirst", isFirst);
Fragment fragment = fragmentManager.getFragmentFactory().instantiate(classLoader, className);
fragment.setArguments(bundle);
return fragment;
}
}
and call it
loadFragment(Util.getThirdFragment(getSupportFragmentManager(),true/*is first boolean value*/, ThirdFragment.class.getClassLoader(), ThirdFragment.class.getName()));
Kotlin
put this code inside ThirdFragment
companion object {
#JvmStatic
fun newInstance(param1: Boolean) =
ThirdFragment().apply {
arguments = Bundle().apply {
putBoolean("isFirst", param1)
}
}
}
use bundleOf("key" to "value") ex :
findNavController(it).navigate(
R.id.action_sendSmsFragment_to_webViewFragment,
bundleOf(
"age" to 25,
"name" to "Michael",
"skill" to null
)
)
Is there a way to check which activity loads a fragment from within the fragment? I have a user profile fragment which is loaded from 2 different activities but only one passes a value in, so when getting values from the bundle when the fragment loads from the activity that doesn't pass a value throws a nullpointerexception. Or is there a better way to pass the value into the fragment so the fragment can get the value only when loaded from this specific activity?
You can simply do this check in your fragment:
if(getActivity() instanceof SomeActivity){
//do something
}
You can also cast the getActivity() call if you are sure which Activity it is (and then call methods from that Activity).
You can define two static methods (also known as Static Factory Methods) which returns instances of your Fragment with the parameters you want to pass with bundle like the following code:
private static final String BUNDLE_VALUE_KEY = "value";
#NonNull
public static YourFragment newInstance() {
return new YourFragment();
}
#NonNull
public static YourFragment newInstance(#NonNull String yourValue) {
final YourFragment instance = new YourFragment();
final Bundle args = new Bundle();
args.putString(BUNDLE_VALUE_KEY,yourValue);
instance.setArguments(args);
return instance;
}
In your Activity which you want to pass the value you can use:
final YourFragment fragment = YourFragment.newInstance(value);
getSupportFragmentManager().beginTransaction()
.replace(R.id.framelayout, fragment)
.commit();
In other Activity you can use:
final YourFragment fragment = YourFragment.newInstance();
getSupportFragmentManager().beginTransaction()
.replace(R.id.framelayout, fragment)
.commit();
And in onCreate method of your Fragment you can check arguments and init your value like the following code:
final Bundle args = getArguments();
if(args != null){
yourValue = args.getString(BUNDLE_VALUE_KEY,null);
}
So if your Fragment is attached to the Activity which passes data you'll have it. If the Fragment is attached to other Activity you'll have the initial value (in the example it's null)
Or you can check the instance of Activity which Fragment gets attached. (Not best practice)
if(getActivity() instanceof YourActivityWhichPassesData){
yourValue = getArguments().getString(BUNDLE_VALUE_KEY,null);
}
This question already has answers here:
How to pass a variable from Activity to Fragment, and pass it back?
(9 answers)
Closed 6 years ago.
I have the following simple code to switch from one fragment to another in the content frame. Is there a simple way to pass variables in the following code?
FragmentManager fm = getActivity().getFragmentManager();
fm.beginTransaction().replace(R.id.content_frame, new TransactionDetailsFragment()).commit();
You can use Bundle:
FragmentManager fm = getActivity().getFragmentManager();
Bundle arguments = new Bundle();
arguments.putInt("VALUE1", 0);
arguments.putInt("VALUE2", 100);
MyFragment myFragment = new Fragment();
fragment.setArguments(arguments);
fm.beginTransaction().replace(R.id.content_frame, myFragment).commit();
Then, you retrieve as follows:
public class MyFragment extends Fragment {
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle bundle = this.getArguments();
if (bundle != null) {
int value1 = bundle.getInt("VALUE1", -1);
int value2 = bundle.getInt("VALUE2", -1);
}
}
}
Or you could use the newInstance method - create a method inside your Fragment class like:
public static TransactionDetailsFragment newInstance(String param) {
TransactionDetailsFragment frag = new TransactionDetailsFragment();
Bundle bund = new Bundle();
bund.putString("paramkey", param); // you use key to later grab the value
frag.setArguments(bund);
return frag;
}
So to create your fragment you do:
TransactionDetailsFragment.newInstance("PASSING VALUE");
(This is used instead of your new TransactionDetailsFragment() )
Then for example in onCreate/onCreateView of the same fragment you get the value like this:
String value = getArguments().getString("paramkey");
How about creating a parameterized constructor for TransactionDetailsFragment?
fm.beginTransaction().replace(R.id.content_frame, new TransactionDetailsFragment(YOUR_PARAMS)).commit();
When you create new TransactionDetailsFragment(YOUR_PARAMS) as a param of FragmentTransaction, I think using constructor is a good choice.
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.
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