How to edit a fragments layout TextView in the MainActivity.java? - android

i was working with a NavigationDrawer for a menu and there is a fragment for every item on the menu for example i have a home menu which have a homefragemnt.xml and a homefragment.java so in the xml file file there is a textview i wanted to change that textviews values using the MainActivity.java
and used the following code:TextView t1 = (TextView) findViewById(R.id.changetxt);t1.setText("ChangedText");
changetxt is the id of the TextView in the homefragment.xml file
but this code give a runtime error saying Attempt to invoke virtual method on a null object reference.
What is causing this problem and how do i solve it?


You will have to get the reference of textview from the fragment view not activity.
The view which you inflated in the onCreateView of fragment.
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.myview,container,false);
TextView t1 = (TextView) view.findViewById(R.id.changetxt);t1.setText("ChangedText");
return view;
}
here view is the View that the fragment is initaialised with.
this link will help you


Fragment :
public class MyFragment extends Fragment {
TextView t1;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_main, container, false);
t1 = (TextView) view.findViewById(R.id.changetxt);
return view;
}
public void setTextViewText(String value){
t1.setText(value);
}
}
Activity :
myFragment.setTextView("ChangedText");
Hope it helps you.

Related

Cannot resolve symbol in Inflater in findViewById [duplicate]

I am trying to create an ImageView in a Fragment which will refer to the ImageView element which I have created in the XML for the Fragment. However, the findViewById method only works if I extend an Activity class. Is there anyway of which I can use it in Fragment as well?
public class TestClass extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
ImageView imageView = (ImageView)findViewById(R.id.my_image);
return inflater.inflate(R.layout.testclassfragment, container, false);
}
}
The findViewById method has an error on it which states that the method is undefined.

Use getView() or the View parameter from implementing the onViewCreated method. It returns the root view for the fragment (the one returned by onCreateView() method). With this you can call findViewById().
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
ImageView imageView = (ImageView) getView().findViewById(R.id.foo);
// or (ImageView) view.findViewById(R.id.foo);
As getView() works only after onCreateView(), you can't use it inside onCreate() or onCreateView() methods of the fragment .

You need to inflate the Fragment's view and call findViewById() on the View it returns.
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
return view;
}

Inside Fragment class you will get onViewCreated() override method where you should always initialize your views as in this method you get view object using which you can find your views like :
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
view.findViewById(R.id.yourId).setOnClickListener(this);
// or
getActivity().findViewById(R.id.yourId).setOnClickListener(this);
}
Always remember in case of Fragment that onViewCreated() method will not called automatically if you are returning null or super.onCreateView() from onCreateView() method.
It will be called by default in case of ListFragment as ListFragment return FrameLayout by default.
Note: you can get the fragment view anywhere in the class by using getView() once onCreateView() has been executed successfully.
i.e.
getView().findViewById("your view id");

I realise this is an old question, but the prevailing answer leaves something to be desired.
The question is not clear what is required of imageView - are we passing it back as the view, or merely saving a reference for later?
Either way, if the ImageView is coming from the inflated layout, the correct way to do this would be:
public class TestClass extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView)v.findViewById(R.id.my_image);
return v;
}
}

Get first the fragment view and then get from this view your ImageView.
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
return view;
}

Inside Fragment class we get onViewCreated() override method where we should always initialize our views because in this method we get view object. Using this object we can find our views like below:
class MyFragment extends Fragment {
private ImageView imageView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.my_fragment_layout, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//initialize your view here for use view.findViewById("your view id")
imageView = (ImageView) view.findViewById(R.id.my_image);
}
}

You could also do it in the onActivityCreated Method.
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
Like they do here: http://developer.android.com/reference/android/app/Fragment.html (deprecated in API level 28)
getView().findViewById(R.id.foo);
and
getActivity().findViewById(R.id.foo);
are possible.

getView() will give the root view
View v = getView().findViewByID(R.id.x);

You can override onViewCreated() which is called right after all views had been inflated. It's the right place to fill in your Fragment's member View variables. Here's an example:
class GalleryFragment extends Fragment {
private Gallery gallery;
(...)
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
gallery = (Gallery) view.findViewById(R.id.gallery);
gallery.setAdapter(adapter);
super.onViewCreated(view, savedInstanceState);
}
}

The method getView() wont work on fragments outside OnCreate and similar methods.
You have two ways, pass the view to the function on the oncreate (what means you can only run your functions when the view is being created) or set the view as a variable:
private View rootView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_contatos, container, false);
}
public void doSomething () {
ImageView thumbnail = (ImageView) rootView.findViewById(R.id.someId);
}

1) first inflate layout of Fragment then you can use findviewbyId .
View view = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView) view.findViewById(R.id.my_image);
return view;

EditText name = (EditText) getView().findViewById(R.id.editText1);
EditText add = (EditText) getView().findViewById(R.id.editText2);

agreed with calling findViewById() on the View.
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View V = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView) V.findViewById(R.id.my_image);
return V;
}

Note :
From API Level 26, you also don't need to specifically cast the result of findViewById as it uses inference for its return type.
So now you can simply do,
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = view.findViewById(R.id.my_image); //without casting the return type
return view;
}

Use
imagebutton = (ImageButton) getActivity().findViewById(R.id.imagebutton1);
imageview = (ImageView) getActivity().findViewById(R.id.imageview1);
it will work

According to the documentation on API level 11
Reference, in Back Stack
http://developer.android.com/reference/android/app/Fragment.html
short code
/**
* The Fragment's UI is just a simple text view showing its
* instance number.
*/
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.hello_world, container, false);
View tv = v.findViewById(R.id.text);
((TextView)tv).setText("Fragment #" + mNum);
tv.setBackgroundDrawable(getResources().getDrawable(android.R.drawable.gallery_thumb));
return v;
}

Using getView() returns the view of the fragment, then you can call findViewById() to access any view element in the fragment view.

Try this it works for me
public class TestClass extends Fragment {
private ImageView imageView;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.testclassfragment, container, false);
findViews(view);
return view;
}
private void findViews(View view) {
imageView = (ImageView) view.findViewById(R.id.my_image);
}
}

1) Declare your layout file.
public View onCreateView(LayoutInflater inflater,ViewGroup container,
Bundle savedInstanceState) {
return inflate(R.layout.myfragment, container, false);
}
2)Then, get the id of your view
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
TextView nameView = (TextView) view.findViewById(R.id.textview1);
}

The best way to implement this is as follows:
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView) rootView.findViewById(R.id.my_image);
return rootView
}
In this way, the rootView can be used for each control defined in the xml layout and the code is much cleaner in this way.
Hope this helps :)

Try This:
View v = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView img = (ImageView) v.findViewById(R.id.my_image);
return v;

try
private View myFragmentView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
myFragmentView = inflater.inflate(R.layout.myLayoutId, container, false);
myView = myFragmentView.findViewById(R.id.myIdTag)
return myFragmentView;
}

Use gradle skeleton plugin, it will automatically generate the view holder classes with the reference to your layout.
public class TestClass extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
MyLayout myLayout = new MyLayout(inflater, container, false);
myLayout.myImage.setImageResource(R.drawable.myImage);
return myLayout.view;
}
}
Now assuming you had an ImageView declared in your my_layout.xml file, it will automatically generate myLayout class for you.

I like everything to be structured. You can do in this way.
First initialize view
private ImageView imageView;
Then override OnViewCreated
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
findViews(view);
}
Then add a void method to find views
private void findViews(View v) {
imageView = v.findViewById(R.id.img);
}

//here you can do it by
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
// Inflate the layout for this fragment
final View view = inflater.inflate(R.layout.fragment_apple, container,
false);
ist = view.findViewById(R.id.linearLink);
second = view.findViewById(R.id.linearPhone);
return view;

ImageView imageView;
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.testclassfragment, container, false);
imageView = view.findViewById(R.id.my_image);
return view;
}

You can call findViewById() with the Activity Object you get inside your public void onAttach(Activity activity) method inside your Fragment.
Save the Activity into a variable for example:
In the Fragment class:
private Activity mainActivity;
In the onAttach() method:
this.mainActivity=activity;
Finally execute every findViewById through the vairable:
mainActivity.findViewById(R.id.TextView);

Inside onCreateView method
1) first you have to inflate the layout/view you want to add
eg. LinearLayout
LinearLayout ll = inflater.inflate(R.layout.testclassfragment, container, false);
2) Then you can find your imageView id from layout
ImageView imageView = (ImageView)ll.findViewById(R.id.my_image);
3)return the inflated layout
return ll;

You have to inflate the view
public class TestClass extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.testclassfragment, container, false);
ImageView imageView = (ImageView)v.findViewById(R.id.my_image);
return v
}}

There is one more method called onViewCreated.
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
ImageView imageView = (ImageView) view.findViewById(R.id.imageview1);
}

does textview in fragment needs to be declared static [duplicate]

This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 4 years ago.
i have started to learn android recently and i was looking at a fragment example in a video tutorial
in the tutorial they haven't made the textview static but when i tried to implement fragment with some changes in the code i started to get null pointer exception my code looks like this
public class BlankFragment2 extends Fragment {
TextView tv;
public BlankFragment2() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_blank_fragment2, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
tv= (TextView) getActivity().findViewById(R.id.txt2);
}
public void setName(String name){
//tv=(TextView)getActivity().findViewById(R.id.txt2);
if(tv == null){
System.out.println("tv is null");
}
tv.setText("Hi "+name);
}
}
i am getting null pointer exception at settext unless i make the textview static can someone please explain why
this is not duplicate of what is NPE i know what NPE is and why it shows up my question here is that after initializing the textview in onActivityCreated why it is null again in setname function

Not getActivity().findViewById(), it must be view.findViewById() because Activity.findViewById() will look for a View in the Activity layout, whereas view.findViewById() will look for the View in the Fragment layout.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View inflatedView = inflater.inflate(R.layout.fragment_blank_fragment2, container, false);
return inflatedView;
}
And in onViewCreated you can initialise your TextView
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// here goes your intialisation using view
tv= (TextView) view.findViewById(R.id.txt2);
}
Make sure you have a TextView with the id txt2 in fragment_blank_fragment2.xml

NullPointerException is thrown when an application attempts to use an
object reference that has the null value.
FYI
You should return VIEW's object
Check findViewById(R.id.txt2 . Make sure you this ID present in XML.
Don't
tv= (TextView) getActivity().findViewById(R.id.txt2);
Do
tv= (TextView) view.findViewById(R.id.txt2);
Try this way
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.fragment_blank_fragment2, container, false);
tv= (TextView) view.findViewById(R.id.txt2);
return view;
}

Sorry guys it was a stupid mistake on my side,
in my mainactivity i wrote
BlankFragment2 frag2 = new BlankFragment2();
frag2.setName(name);
i corrected it by writing
BlankFragment2 frag2=(BlankFragment2)getFragmentManager().findFragmentById(R.id.frag2);
fragb.setName(name);
now it is working

Android Tabbed Activity on clickbutton not work

Can someone tell me how to set a button in tabbed fragment layout to open a new activity? If I set a button in a tab then it shows error.

You have to save the inflated view in a variable, then use findViewById on that view to find the textview and button, then at the end, return the inflated view.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View root = inflater.inflate(R.layout.fragment_g, container, false);
TextView tv = (TextView) root.findViewById(R.id.textView);
Button btn = (Button) root.findViewById(R.id.button);
//Other code here
return root;
}
You're misunderstanding some very fundamental things, such as writing code after the return statement. You might want to read some starter guides online.

You can use below code
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.activity_complete_registration, container, false);
final TextView tv=(TextView)view.findViewById(R.id.textView);
final Button button=(Button)view.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//Your required code here
}
});
return view;
}

How to Set Text to the text view in Fragment Activity programmatically?

I have a Fragment Activity i need to set Text to the text view in that Activity,when i am using following code getting null pointer exception.
can any other approach is there to set data for text view .
public class Introduction extends Fragment {
TextView txt;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v= inflater.inflate(R.layout.activity_introduction, container, false);
txt=(TextView) v.findViewById(R.id.officeheader);
return v;
}
public void setText(String text){
txt.setText(text);
}
}
and in My Fragment Activity class :
frgManager=getSupportFragmentManager();
frgManager.beginTransaction()
. replace(R.id.fragmentoffice, introduction,"introduction")
.commit();
introduction.setText(" Office Coffee that will \n have everyone talking ");

set string in bundle
Bundle bundl = new Bundle();
bundl.putString("Text", text);
introduction.setArguments(bundl)
frgManager=getSupportFragmentManager();
frgManager.beginTransaction()
. replace(R.id.fragmentoffice, introduction,"introduction")
.commit();
get text from bundle
public class Introduction extends Fragment {
TextView txt;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
String str = getArguments().getString("Text");
View v= inflater.inflate(R.layout.activity_introduction, container, false);
txt=(TextView) v.findViewById(R.id.officeheader);
setText(str);
return v;
}
public void setText(String text){
txt.setText(text);
}
}

you can write introduction constructor ,which contain a parameter Type String ,
and on the onCreateView ,you can initialize the textivew and settext

Fragment/View. How to use a method on a View

I'm doing a Navigation Drawer app. I have all the cases working, I mean, when in touch a section the app goes to the right View. But when I want to start coding I don't know how to use methods inside the View. I think my code will explain better than me:
public class News extends android.support.v4.app.Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
setText();
return inflater.inflate(R.layout.lay_news, container, false);
}
public void setText(){
TextView texts = (TextView) getView().findViewById(R.id.textView);
texto.setText("hi");
}
}
NullPointerException when I call the method setText. I know that it's the TextView definition, but I don't know how to "find" it in the layout without getView() or getActivty(), both return a NullPointerException when the view loads.

Just do
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v=inflater.inflate(R.layout.lay_news, container, false);
setText(v);
return v;
}
and
public void setText(View v){
TextView texts = (TextView)v.findViewById(R.id.textView);
texto.setText("hi");
}

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