片段TextView无法从可包裹对象更新

Question

In my fragment, I have a textView which I want to set to a specific String. I want to get the String for the textView from an object, which I send to the fragment as a parcelable. I can retrieve the parcelable object and use the object to get the String (when I log it, the correct String is displayed). But when I want to use this to set the textView, the textView doesn't change.

Any ideas why this happens and how I can fix it?

Thanks!

Edit1: I added the activity the fragment is located in to, maybe the error is here?

Edit2: I added the Data class (the parcelable object). But removed the content of the constructor just to keep it easy to read.

public class NavigationFragment extends Fragment {

    private static final String TAG = "NavigationFragment";

    public NavigationFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_navigation, container, false);
        return view;
    }

    @Override
    public void onViewCreated(@NonNull final View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
       Bundle bundle = this.getArguments();
        if(bundle!=null) {
            Data data = (Data) bundle.getParcelable("data");
            TextView stopTitle = (TextView) view.findViewById(R.id.stopTitle);
            final String name = data.getTourName();
            Log.d(TAG, name);
            stopTitle.setText(name);
        }
    }

}

<?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"
    android:background="@color/colorAccent"
    tools:context=".DoTourActivity">

    <TextView
        android:id="@+id/stopTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="stopTitle"
        android:textSize="30dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="365dp"
        android:layout_height="158dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.492"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/stopTitle"
        tools:src="@drawable/placeholder_pic" />

    <TextView
        android:id="@+id/stopDescription"
        android:layout_width="384dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="24dp"
        android:text="stopDescriptionstopDescriptionstopDescription stopDescription stopDescription stopDescription stopDescription stopDescription stopDescription stopDescription stopDescriptionstopDescriptionstopDescription stopDescription stopDescription stopDescription stopDescription stopDescription stopDescription stopDescription"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/imageView" />

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="395dp"
        android:layout_height="40dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="8dp"
        android:orientation="horizontal"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/stopDescription">

        <ImageView
            android:id="@+id/imageView3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:src="@android:drawable/ic_menu_mylocation" />

        <TextView
            android:id="@+id/locationAdress"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="locationAdress"
            android:textSize="23dp" />

        <ImageView
            android:id="@+id/imageView2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:src="@android:drawable/ic_dialog_map" />

    </LinearLayout>

    <EditText
        android:id="@+id/pincode"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="8dp"
        android:ems="10"
        android:inputType="number"
        android:text="pincode"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/linearLayout" />

    <Button
        android:id="@+id/confirmButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="confirm"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/pincode" />

</android.support.constraint.ConstraintLayout>

public class DoTourActivity extends AppCompatActivity {

    private static final String TAG = "DoTourActivity";

    private SectionStatePagerAdapter sectionStatePagerAdapter;
    private ViewPager viewPager;

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_do_tour);

        //Fragment management
        sectionStatePagerAdapter = new SectionStatePagerAdapter(getSupportFragmentManager());
        viewPager = (ViewPager) findViewById(R.id.container);
        setupViewPager(viewPager);

        //Setup actionbar
        Toolbar myToolbar = (Toolbar) findViewById(R.id.app_bar);
        setSupportActionBar(myToolbar);


        //get chosen location & build tour
        Fragment fragment = new NavigationFragment();
        String location = getIntent().getStringExtra("location");
        Bundle bundle = new Bundle();
        Data data = new Data(location);
        bundle.putParcelable("data", data);
        fragment.setArguments(bundle);

        //launch fragment
        FragmentManager manager = getSupportFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.replace(R.id.container, fragment);
        transaction.commit();
    }

    public void setupViewPager (ViewPager viewPager) {
        SectionStatePagerAdapter adapter = new SectionStatePagerAdapter(getSupportFragmentManager());
        adapter.addFragment(new NavigationFragment(), "navFragment");
        adapter.addFragment(new QuestionFragment(), "qesFragment");
        viewPager.setAdapter(adapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
//        switch(item.getItemId())
        return super.onOptionsItemSelected(item);
    }
}

public class Data implements Parcelable {

    public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {
        public Data createFromParcel(Parcel in) {
            return new Data(in);
        }

        public Data[] newArray(int size) {
            return new Data[size];
        }
    };

    private String tourName;
    int tourID;
    int possiblePoints;
    int stops;
    Spot[] spots;

    //while playing tour
    int points = 0;

    // Constructor
    public Data(String tour){

    }

    public String getTourName() {
        return tourName;
    }

    public void setTourName(String tourName) {
        this.tourName = tourName;
    }

    public int getTourID() {
        return tourID;
    }

    public void setTourID(int tourID) {
        this.tourID = tourID;
    }

    public int getPossiblePoints() {
        return possiblePoints;
    }

    public void setPossiblePoints(int possiblePoints) {
        this.possiblePoints = possiblePoints;
    }

    public int getStops() {
        return stops;
    }

    public void setStops(int stops) {
        this.stops = stops;
    }

    public Spot[] getSpots() {
        return spots;
    }

    public void setSpots(Spot[] spots) {
        this.spots = spots;
    }

    public int getPoints() {
        return points;
    }

    public void setPoints(int points) {
        this.points = points;
    }

    // Parcelling part
    public Data(Parcel in){
        this.tourName =  in.readString();
        this.tourID =  in.readInt();
        this.possiblePoints =  in.readInt();
        this.stops =  in.readInt();
        this.spots = in.createTypedArray(Spot.CREATOR);
        this.points = in.readInt();
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(this.tourName);
        dest.writeInt(this.tourID);
        dest.writeInt(this.possiblePoints);
        dest.writeInt(this.stops);
        for(Spot s : spots){
            dest.writeParcelable(s, flags);
        }
        dest.writeInt(this.points);
    }


}

Answer 1

Thanks to @Mike M. this is solved.

The problem was with the activity in which the fragments were hosted. In there I created two different NavigationFragments which I added to the activity. The updating of the TextView happen on the wrong one.

Answer 2

I see from another answer that there was a problem with fragment instances, but I believe you also have a problem with your Parcelable implementation.

 public Data(Parcel in){ ... this.spots = in.createTypedArray(Spot.CREATOR); ... } @Override public void writeToParcel(Parcel dest, int flags) { ... for(Spot s : spots){ dest.writeParcelable(s, flags); } ... } 

These two calls need to be mirrored, and they currently are not. Rather than iterating over the array yourself, you should use the writeTypedArray() method:

public Data(Parcel in){
    ...
    this.spots = in.createTypedArray(Spot.CREATOR);
    ...
}

@Override
public void writeToParcel(Parcel dest, int flags) {
    ...
    dest.writeTypedArray(spots, flags);
    ...
}

If you look at the implementations for writeTypedArray() and createTypedArray() , you'll see that part of the work is to write a flag that indicates the size of the array, so that the code knows how many instances to read out on the other side. Your implementation does not include this step, so the two will be incompatible.