In my Android app I've got an EditText to which I want to do a setError() when it is empty. The EditText is located in a file called fragment_amount.
<?xml version="1.0" encoding="utf-8"?>
<EditText xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_amount"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"
/>
and I load this in a Fragment like so:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_amount, null);
}
From within the parent fragment of the fragment in which this EditText is initially loaded (using the snippet above) I now want to use setError like so:
EditText amountField = (EditText) getView().findViewById(R.id.fragment_amount);
amountField.setError("ERRROROROROR");
Unfortunately, I get a ClassCastException on the first line, saying: android.support.v4.app.NoSaveStateFrameLayout cannot be cast to android.widget.EditText. The strange thing it that in the fragment in which I initially load this EditText (AmountFragment.java), it is loaded in exactly the same way, without any errors.
Does anybody know how I can load this EditText in the parent fragment as an EditText so that I can use the setError() method? All tips are welcome!
Try this...
You have given the name fragment_amount for your layout and also you have given the same name as id for your edittext.
So, try changing the id for your edittext in both xml and java.(For example, here i have given as fragment_amount_edit)
XML :
<?xml version="1.0" encoding="utf-8"?>
<EditText xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_amount_edit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"
/>
JAVA :
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_amount, null);
EditText amountField = (EditText) view.findViewById(R.id.fragment_amount_edit);
amountField.setError("ERRROROROROR");
return view;
}
Some times the same name of layout or any other widget can be conflicted.
In your code there is same id of EditText is fragment_amount and same layout name as fragment_amount. So it is being conflicted.
Change from here:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_amount, null);
Now you are inflating your layout to View. So object of that View must be referenced to find the id of EditText. So
EditText edt= (EditText) view.findViewById(R.id.youreditId);
edt.setError("ERRROROROROR");
return view;
}
Related
I'm doing a recycler method in my android studio project but i have a problem.
Everytime i'm trying to findViewById my application is crashing.
Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
And i don't understand why because i'm creating my view in the good way.
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_carrito, container, false);
return view;
}
And i'm trying to continue with that
#Override
public void onAttach(#NonNull Context context) {
super.onAttach(context);
...
Log.e("test : ",Integer.toString(R.id.recyclerBuy));
recyView = view.findViewById(R.id.recyclerBuy);
/* recyView.setLayoutManager(new GridLayoutManager(getContext(),RecyclerView.VERTICAL));
recyView.setAdapter(buyAdapter);
*/
}
But i'm crashing at the line recyView = view.findViewById(R.id.recyclerBuy);. My R.id.recyclerBuy is not empty.
And here is my RecyclerView
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".ui.carrito.CarritoFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerBuy"
android:layout_width="match_parent"
android:layout_height="550dp"
android:layout_marginBottom="88dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent" />
...
</androidx.constraintlayout.widget.ConstraintLayout>
Anyone have a clue why i'm crashing everytime ?
This happens because onAttach() callback is called before onCreateView().
The easiest way to fix the issue is placing the code where you finding your RecyclerView in onCreateView(). Something like:
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_carrito, container, false);
recyView = view.findViewById(R.id.recyclerBuy);
// here you recyView won't be null
return view;
}
A good article about fragments lifecycle: https://medium.com/androiddevelopers/the-android-lifecycle-cheat-sheet-part-iii-fragments-afc87d4f37fd
I have two APKs. First APK is a main APK which loads second APK.
MainActivity.java (first APK): Object mainFragment was loaded by DexClassLoader early
setContentView(R.layout.activity_main);
LinearLayout fragContainer = findViewById(R.id.main_fragment);
LinearLayout ll = new LinearLayout(context);
ll.setOrientation(LinearLayout.HORIZONTAL);
ll.setId(View.generateViewId());
getSupportFragmentManager().beginTransaction().add(ll.getId(), mainFragment, "mainFragment").commit();
fragContainer.addView(ll);
activity_main.xml (first APK):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:id="#+id/main_fragment"
android:orientation="vertical"
/>
</LinearLayout>
MainFragment.java (second APK):
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main, viewGroup, false);
view.findViewById(R.id.emailSignInButton).setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
}
});
return view;
}
fragment_main.xml (second APK):
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:text="#string/sign_in"
android:layout_width="88dp"
android:layout_height="wrap_content"
android:id="#+id/emailSignInButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="32dp"
android:layout_marginEnd="32dp" android:layout_marginTop="8dp"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>
I don't understand, why in the line
View view = inflater.inflate(R.layout.fragment_main, viewGroup, false);
view is always NULL. Do I need to load R.layout.fragment_main into memory like mainFragment?
#CommonsWare already answered you: you are loading classes, not resources.
In Android´s packages, you have both classes (Like R), and resources (Preprocessed XML files, like layouts, for example). A ClassLoader is capable of reading and loading the first ones, so, loading another´s APK R class is possible. But R´s indexes just point towards resource files, they don´t contain the actual values of said resources. So, the R class you sideloaded does not provide the route to a valid resource. If R could do that, then the APK/AAR/APKLib formats would not exists; regular JAR files would suffice. But they don`t,because android resource files are different from class files, and thus, a "link" of sorts is necessary to make them visible to your classes: the R class.
if you want to make your current code work, you need to replace fragment_main.xml with a coded viewgroup instance. Create a class/method providing a constraintLayout instance housing your button (MyViewFactory.createConstraintLayoutWithButton, for example), set the properties via code, and replace
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main, viewGroup, false);
view.findViewById(R.id.emailSignInButton).setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
}
});
return view;
}
with something like
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle savedInstanceState) {
View view = MyViewFactory.createConstraintLayoutWithButton(getContext)
view.findViewById(R.id.emailSignInButton).setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
}
});
return view;
}
As long as you don´t use resources, you´ll be fine. That said, this approach is quite fragile, so maybe it would be better to create intent filters between your APKs in order to make APK 2 to work for APK 1.
Edit:
You can use the R constants as ids for your code generated views, as long as you set them manually first. For example:
public static ConstraintLayout createConstraintLayoutWithButton(Context context){
Constraintlayout mylayout = new ConstraintLayout(context);
//set up of the layout
Button myButton = new Button(context);
//set up of the button
button.setId(R.id.emailSignInButton);
myLayout.addView(button);
return mylayout;
}
And then you can locate that button with the id.
Alright so I have a fragment and I'd like to include, within its' xml file another layout which is programmatically inflated
Fragment:
public class zGoal_Fragment extends Fragment{
private LinearLayout todayView;
private View view;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.main_goal_view, container, false);
todayView = (LinearLayout)view.findViewById(R.id.todayView);
return view;
}
}
xml's file for fragment:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:id="#+id/todayView"
>
</LinearLayout>
and xml layout I want included within the above xml programmatically:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/goalEditLayout"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="100dp"
android:background="#color/test_color_two"
>
</LinearLayout>
I've tried a couple different methods all of which led to " on a null object reference" errors...
plz help :))
I suppose the solution which you are looking for are Android ViewStubs. These are dynamically inflated layouts.
For more information you could refer these :
How to use View Stub in android
https://developer.android.com/reference/android/view/ViewStub.html
However, if you don't wish to inflate one layout inside another during runtime, you could try this the include tag:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:id="#+id/todayView">
<include layout="#layout/your_layout_file_name"/>
</LinearLayout>
Have you tried something like this:
LinearLayout child = getLayoutInflater().inflate(R.layout.goalEditLayout, null);
todayView.addView(child);
Edit:
Inside onCreateView:
LinearLayout inflatedLayout = (LinearLayout) inflater.inflate(R.layout.goalEditLayout, todayView, true);
I have read all the other topics related to this issue and none seem to be helping me solve the problem.
I am doing some background task in an asynctask that needs to persist on orientation change (configChanges). I have gotten the data to persist I believe by using fragments and setRetainInstance(true), but my buttons (Im assuming any views really) are being set to null on recreation of the fragment on orientation change. This is causing a null pointer error when I try to operate on the buttons reference after orientation has change (fragment has been recreated).
I have tried wrapping the button and calls on the button in a statement to check if the bundle is null. This stops the crash but does not allow for the button to be used again on recreation of the fragment.
The following class extends Fragment.
#Override
public void onCreate(Bundle savedInstanceState) {
if (DEBUG) Log.d(TAG, "onCreate()");
super.onCreate(savedInstanceState);
setRetainInstance(true);
currentActivity = super.getActivity();
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
if (DEBUG) Log.d(TAG, "onActivityCreated(Bundle)");
super.onActivityCreated(savedInstanceState);
simpleForecastIntent = new Intent(currentActivity, SimpleForecastActivity.class);
Button fetchDataButton = (Button) currentActivity.findViewById(R.id.fetchDataButton);
if (savedInstanceState == null) {
fetchDataButton.setOnClickListener(fetchDataButtonListener);
fetchDataButton.setTransformationMethod(null);
}
locationManager = (LocationManager)
currentActivity.getSystemService(Context.LOCATION_SERVICE);
if (isTaskRunning) {
progressDialog = ProgressDialog.show(currentActivity, "Fetching data", "Please wait...");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (DEBUG) Log.d(TAG, "onCreateView(LayoutInflater, ViewGroup, Bundle)");
return inflater.inflate(R.layout.main_menu, container, false);
}
main_menu.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".activities.MainActivity">
<include layout="#layout/toolbar" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp">
<Button
android:id="#+id/fetchDataButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/locationField"
android:text="#string/fetch_weather_data"
android:layout_centerHorizontal="true" />
<EditText
android:id="#+id/locationField"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="#string/enter_location"
android:layout_alignEnd="#+id/fetchDataButton"
android:layout_alignLeft="#+id/fetchDataButton"
android:layout_alignRight="#+id/fetchDataButton"
android:layout_alignStart="#+id/fetchDataButton"
android:inputType="textPostalAddress" />
<ListView
android:id="#+id/previousLocationsList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/fetchDataButton"
android:layout_centerHorizontal="true" />
</RelativeLayout>
</LinearLayout>
I have spent far too many hours on something so trivial and really need a bump in the correct direction. How can I get the button to not be null on recreation of fragment?
EDIT SOLVED:
I was using the disposed of activity's context to find the view of the button. Instead of the new activities view context.
#Override
public void onCreate(Bundle savedInstanceState) {
if (DEBUG) Log.d(TAG, "onCreate()");
super.onCreate(savedInstanceState);
setRetainInstance(true);
currentActivity = super.getActivity();
}
The problem is that you are referencing your button in onActivityCreated instead of onCreateView. On orientation change, the view gets torn down and then recreated. You should override onCreateView and maintain the reference to your button from there.
UPDATE:
I see how your code is working, but in my opinion it's following a bad design pattern. You are still instantiating your view references inside of onActivityCreated, instead of immediately after they are inflated in onCreateView.
I would switch it to something like this:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (DEBUG) Log.d(TAG, "onCreateView(LayoutInflater, ViewGroup, Bundle)");
View root = inflater.inflate(R.layout.main_menu, container, false);
Button fetchDataButton = (Button) root.findViewById(R.id.fetchDataButton);
...
return root;
}
I'm simply trying to change the text of a textView that is located within the actual fragment. It isn't throwing any error but it simply isn't updating. Aside from this the fragment successfully attaches to the activity via a viewpager.
The fragment:
public class FragmentPlotData extends Fragment {
public static TextView textViewPlotData;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_plot_data, container, false);
textViewPlotData = (TextView) view.findViewById(R.id.textViewPlotData);
textViewPlotData.setText("Changed text ");
return inflater.inflate(R.layout.fragment_plot_data, container, false);
}
}
The fragment's layout:
<TextView
android:id="#+id/textViewPlotData"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="30sp"
android:textColor="#color/black_process_2"
android:text="#string/original text"
android:gravity="center"/>
</RelativeLayout>
You should return view in onCreateView, don't inflate a new layout like that.
Just replace:
return inflater.inflate(R.layout.fragment_plot_data, container, false);
to:
return view;