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Исключение нулевого указателя для OnGridImageSelectedListener.onGridImageSelected

#java #android #android-fragments #nullpointerexception

#java #Android #android-фрагменты #исключение nullpointerexception

Вопрос:

Я получаю java.lang.NullPointerException : попытка вызвать метод интерфейса ‘void com.umo2.players.Профиль.MomentsActivity$OnGridImageSelectedListener.onGridImageSelected(com.umo2.players.models.Фото, int)’ для ссылки на нулевой объект Я новичок в этом, и я не понимаю, как я получаю ошибку, может кто-нибудь показать мне выход вот мой журнал cat

 E/AndroidRuntime: FATAL EXCEPTION: main

Process: com.umo2.players, PID: 29955

    java.lang.NullPointerException: Attempt to invoke interface method 'void com.umo2.players.Profile.MomentsActivity$OnGridImageSelectedListener.onGridImageSelected(com.umo2.players.models.Photo, int)' on a null object reference
    at com.umo2.players.Profile.MomentsFragment$1$1.onItemClick(MomentsFragment.java:163)
    at android.widget.AdapterView.performItemClick(AdapterView.java:318)
    at android.widget.AbsListView.performItemClick(AbsListView.java:1158)
    at android.widget.AbsListView$PerformClick.run(AbsListView.java:3127)
    at android.widget.AbsListView$3.run(AbsListView.java:4073)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6739)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:449)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

D/HprofFactory: создать HprofDebugEx

это мой фрагмент

 private static final String ARG_PARAM1 = "param1";

private static final String ARG_PARAM2 = "param2";

private static final String TAG = "MomentsActivity";
private static final int NUM_GRID_COLUMNS = 3;

private ProgressBar mProgreesBar;
private GridView gridView;
private Toolbar toolbar;
private FrameLayout parentFrameLayout;

public interface OnGridImageSelectedListener{
    void onGridImageSelected(Photo photo, int activityNumber);
}
MomentsActivity.OnGridImageSelectedListener mOnGridImageSelectedListener;
private BottomNavigationViewEx bottomNavigationView;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListner;
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference myRef;
private FirebaseMethods mFirebaseMethods;
private Context mContext;
private static final int ACTIVITY_NUM = 4;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;

public MomentsFragment() {
    // Required empty public constructor
}

/**
 * Use this factory method to create a new instance of
 * this fragment using the provided parameters.
 *
 * @param param1 Parameter 1.
 * @param param2 Parameter 2.
 * @return A new instance of fragment MomentsFragment.
 */
// TODO: Rename and change types and number of parameters
public static MomentsFragment newInstance(String param1, String param2) {
    MomentsFragment fragment = new MomentsFragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.activity_moments, container, false);
    // tempGridSetup();
    gridView = (GridView) view.findViewById(R.id.gridView);
    toolbar = (Toolbar) view.findViewById(R.id.momentToolBar);
    bottomNavigationView = (BottomNavigationViewEx) view.findViewById(R.id.bottomNavViewBar);
    mContext = getActivity();
    parentFrameLayout = getActivity().findViewById(R.id.momentsFrame);

    setupBottomNavigationView();
    setupGridView();
    return view;
}
@Override
public void onAttach(Context context) {
    try{
        mOnGridImageSelectedListener = (MomentsActivity.OnGridImageSelectedListener) getActivity();
    }catch (ClassCastException e){
        Log.e(TAG, "onAttach: ClassCastException: "   e.getMessage() );
    }
    super.onAttach(context);
}
private void setupGridView() {

    Log.d(TAG, "setupGridView: Setting up image grid.");

    final ArrayList<Photo> photos = new ArrayList<>();
    DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
    Query query = reference
            .child(getString(R.string.dbname_user_photos))
            .child(FirebaseAuth.getInstance().getCurrentUser().getUid());

    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for ( DataSnapshot singleSnapshot :  dataSnapshot.getChildren()){
                photos.add(singleSnapshot.getValue(Photo.class));
                // Photo photo = new Photo();
                //Map<String, Object> objectMap = (HashMap<String, Object>) singleSnapshot.getValue();

            }

            int gridWidth = getResources().getDisplayMetrics().widthPixels;
            int imageWidth = gridWidth/NUM_GRID_COLUMNS;
            gridView.setColumnWidth(imageWidth);

            ArrayList<String> imgUrls = new ArrayList<String>();
            for(int i = 0; i < photos.size(); i  ){
                imgUrls.add(photos.get(i).getImage_path());
            }
            GridImageAdapter adapter = new GridImageAdapter(getActivity(),R.layout.layout_grid_imageview, "", imgUrls);
            gridView.setAdapter(adapter);
            gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    mOnGridImageSelectedListener.onGridImageSelected(photos.get(position), ACTIVITY_NUM);
                }
            });
        }

        @Override
        public void onCancelled(@NonNull DatabaseError error) {
            Log.d(TAG, "onCancelled: query cancelled.");
        }
    });
}

это моя фотомодель

 public class Photo implements Parcelable 
{
private String caption;
private String date_created;
private String image_path;
private String photo_id;
private String user_id;
private String tags;

public Photo(String caption, String date_created, String image_path, String photo_id, String user_id, String tags) {
    this.caption = caption;
    this.date_created = date_created;
    this.image_path = image_path;
    this.photo_id = photo_id;
    this.user_id = user_id;
    this.tags = tags;
}
public Photo() {
}

protected Photo(Parcel in) {
    caption = in.readString();
    date_created = in.readString();
    image_path = in.readString();
    photo_id = in.readString();
    user_id = in.readString();
    tags = in.readString();
}

public static final Creator<Photo> CREATOR = new Creator<Photo>() {
    @Override
    public Photo createFromParcel(Parcel in) {
        return new Photo(in);
    }

    @Override
    public Photo[] newArray(int size) {
        return new Photo[size];
    }
};

public String getCaption() {
    return caption;
}

public void setCaption(String caption) {
    this.caption = caption;
}

public String getDate_created() {
    return date_created;
}

public void setDate_created(String date_created) {
    this.date_created = date_created;
}

public String getImage_path() {
    return image_path;
}

public void setImage_path(String image_path) {
    this.image_path = image_path;
}

public String getPhoto_id() {
    return photo_id;
}

public void setPhoto_id(String photo_id) {
    this.photo_id = photo_id;
}

public String getUser_id() {
    return user_id;
}

public void setUser_id(String user_id) {
    this.user_id = user_id;
}

public String getTags() {
    return tags;
}

public void setTags(String tags) {
    this.tags = tags;
}

@Override
public String toString() {
    return "Photo{"  
            "caption='"   caption   '''  
            ", date_created='"   date_created   '''  
            ", image_path='"   image_path   '''  
            ", photo_id='"   photo_id   '''  
            ", user_id='"   user_id   '''  
            ", tags='"   tags   '''  
            '}';
}

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

@Override
public void writeToParcel(Parcel parcel, int i) {
    parcel.writeString(caption);
    parcel.writeString(date_created);
    parcel.writeString(image_path);
    parcel.writeString(photo_id);
    parcel.writeString(user_id);
    parcel.writeString(tags);
}

this is my activity

 public class MomentsActivity extends AppCompatActivity implements 
MomentsFragment.OnGridImageSelectedListener {
private static final String TAG = "MomentsActivity";
private static final int NUM_GRID_COLUMNS = 3;

private ProgressBar mProgreesBar;
private GridView gridView;
private Toolbar toolbar;
private FrameLayout parentFrameLayout;

public interface OnGridImageSelectedListener{
    void onGridImageSelected(Photo photo, int activityNumber);
}
OnGridImageSelectedListener mOnGridImageSelectedListener;

private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListner;
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference myRef;
private FirebaseMethods mFirebaseMethods;
private static final int ACTIVITY_NUM = 4;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_moments);
    Log.d(TAG, "onCreate: started.");

    init();


}


private void tempGridSetup() {
    ArrayList<String> imgURLs = new ArrayList<>();
    imgURLs.add("https://pbs.twimg.com/profile_images/616076655547682816/6gMRtQyY.jpg");
    imgURLs.add("https://i.redd.it/9bf67ygj710z.jpg");
    imgURLs.add("https://c1.staticflickr.com/5/4276/34102458063_7be616b993_o.jpg");
    imgURLs.add("http://i.imgur.com/EwZRpvQ.jpg");
    imgURLs.add("http://i.imgur.com/JTb2pXP.jpg");
    imgURLs.add("https://i.redd.it/59kjlxxf720z.jpg");
    imgURLs.add("https://i.redd.it/pwduhknig00z.jpg");
    imgURLs.add("https://i.redd.it/clusqsm4oxzy.jpg");
    imgURLs.add("https://i.redd.it/svqvn7xs420z.jpg");
    imgURLs.add("http://i.imgur.com/j4AfH6P.jpg");
    imgURLs.add("https://i.redd.it/89cjkojkl10z.jpg");
    imgURLs.add("https://i.redd.it/aw7pv8jq4zzy.jpg");

    //setupImageGrid(imgURLs);
}

/*

     private void setupImageGrid(ArrayList<String> imgURLs) {
    GridView gridView = (GridView) findViewById(R.id.gridView);
    int gridWidth = getResources().getDisplayMetrics().widthPixels;
    int imageWidth = gridWidth / NUM_GRID_COLUMNS;
    gridView.setColumnWidth(imageWidth);

    GridImageAdapter adapter = new GridImageAdapter(mContext, R.layout.layout_grid_imageview, "", imgURLs);
    gridView.setAdapter(adapter);
}

*/

 @Override
public void onGridImageSelected(Photo photo, int activityNumber) {
    Log.d(TAG, "onGridImageSelected: selected an image gridview: "   photo.toString());


    ViewPostFragment fragment = new ViewPostFragment();
    Bundle args = new Bundle();

    args.putParcelable(getString(R.string.photo), photo);
    args.putInt(getString(R.string.activity_number), activityNumber);


    fragment.setArguments(args);


    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    transaction.replace(R.id.momentsFrame, fragment);

    transaction.addToBackStack(getString(R.string.view_post_fragment));

    transaction.commit();

}
private void init() {
    Log.d(TAG, "init: inflating "   getString(R.string.moments_fragment));

    MomentsFragment fragment = new MomentsFragment();
    FragmentTransaction transaction = MomentsActivity.this.getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.container, fragment);
    transaction.addToBackStack(getString(R.string.moments_fragment));
    transaction.commit();
}

}

Ответ №1:

Внутри вашего фрагмента:

 OnGridImageSelectedListener mOnGridImageSelectedListener;
public void setListener(OnGridImageSelectedListener listener) {
    mOnGridImageSelectedListener = listener;
}

В вашей деятельности:

удалить

 public interface OnGridImageSelectedListener{
    void onGridImageSelected(Photo photo, int activityNumber);
}

затем добавьте fragment.setListener

 private void init() {
    Log.d(TAG, "init: inflating "   getString(R.string.moments_fragment));

    MomentsFragment fragment = new MomentsFragment();
    FragmentTransaction transaction = MomentsActivity.this.getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.container, fragment);
    transaction.addToBackStack(getString(R.string.moments_fragment));
    transaction.commit();
    fragment.setListener(MomentsActivity.this);
}

Комментарии:

1. Когда я пытаюсь создать OnGridImageSelectedListener в моем фрагменте, он показывает ошибку, потому что это не класс

2. удалить метод onAttach

3. Фрагмент.setListener(MomentsACtivity.this) содержит ошибку

4. Также у меня возникает ошибка при выполнении moments activity, @Override public void onGridImageSelected(Photo photo, int activityNumber) { Log.d(ТЕГ, «onGridImageSelected: выбрано изображение gridview: » фото. toString()); ViewPostFragment фрагмент = новый ViewPostFragment(); Bundle args = новый Bundle(); args.putParcelable(getString(R.string.photo), photo); args.putInt(getString(R.string.activity_number), activityNumber); fragment.setArguments(аргументы);

5. удалите интерфейс OnGridImageSelectedListener в вашем действии, затем используйте интерфейс OnGridImageSelectedListener в вашем фрагменте