I have two fragments :
- HomeFragment that extends Fragment
- SettingsFragment that extends PreferenceFragment
Each one contains a TextView that I wish to access and modify its content in the Java code. I make this modification inside the onViewCreated by calling findViewById and then, using setText on the TextView.
This works fine for HomeFragment, but it does not in SettingsFragment.
For information, the TextView of SettingsFragment is defined in the layout associated to the Preference. Strangely, it seems that the views hierarchy of PreferenceFragment type is not fully ready in the onViewCreated ! To go further, I tried to put the code that modifies the TextView after some delay (using postDelay), and that worked !
Below, I put all the code necessary to test the issue I have just raised.
MainActivity.java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final HomeFragment homeFragment = new HomeFragment();
final SettingsFragment settingsFragment = new SettingsFragment();
getFragmentManager().beginTransaction()
.add(R.id.fragmentContainer, homeFragment).commit();
// Just a simple button to switch between the two fragments
Button button = findViewById(R.id.activityButton);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(homeFragment.isAdded()) {
getFragmentManager().beginTransaction()
.replace(R.id.fragmentContainer, settingsFragment).commit();
} else {
getFragmentManager().beginTransaction()
.replace(R.id.fragmentContainer, homeFragment).commit();
}
}
});
}
}
HomeFragment.java
public class HomeFragment extends Fragment {
public HomeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home, container, false);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
TextView textView = view.findViewById(R.id.homeText);
if(textView != null) {
textView.setText("Home fragment text (modified)");
}
}
}
SettingsFragment.java
public class SettingsFragment extends PreferenceFragment {
public SettingsFragment() {
// Required empty public constructor
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.fragment_settings);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return super.onCreateView(inflater, container, savedInstanceState);
}
@Override
public void onViewCreated(final View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// ---- BLOCK 1 -----
TextView textView = view.findViewById(R.id.settingsText);
if (textView != null) {
textView.setText("Preference 1 (modified)");
}
// ---- BLOCK 2 -----
// view.post(new Runnable() {
// @Override
// public void run() {
// TextView textView = view.findViewById(R.id.settingsText);
// if (textView != null) {
// textView.setText("Preference 1 (modified)");
// }
// }
// });
// ---- BLOCK 3 -----
// view.postDelayed(new Runnable() {
// @Override
// public void run() {
// TextView textView = view.findViewById(R.id.settingsText);
// if (textView != null) {
// textView.setText("Preference 1 (modified)");
// }
// }
// }, 100);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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"
tools:context=".MainActivity">
<TextView
android:id="@+id/activityText"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:gravity="center_horizontal"
android:text="MainActivity" />
<Button
android:id="@+id/activityButton"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/activityText"
android:text="Change fragment"/>
<FrameLayout
android:id="@+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="@id/activityButton"
app:layout_constraintBottom_toBottomOf="parent">
</FrameLayout>
</android.support.constraint.ConstraintLayout>
fragment_home.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".HomeFragment">
<TextView
android:id="@+id/homeText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:text="Home fragment text" />
</android.support.constraint.ConstraintLayout>
fragment_settings.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<PreferenceCategory
android:layout="@layout/preference_layout_category">
<Preference
android:enabled="true"
android:layout="@layout/preference_layout" />
</PreferenceCategory>
</PreferenceScreen>
preference_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:id="@+id/settingsText"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:textAllCaps="true"
android:text="Preference 1"/>
</android.support.constraint.ConstraintLayout>
preference_layout_category.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:id="@+id/settingsTextContainer"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:textAllCaps="true"
android:background="@android:color/background_dark"
android:textColor="@android:color/background_light"
android:text="Category 1"/>
</android.support.constraint.ConstraintLayout>
I had something similar the other day. Use findViewById() in the on onCreateView of the fragment instead of the onViewCreated method. Good luck.