如何删除View分页器的特定位置

Question

I implement a ViewPager in my Android App. and i want to add some images in it, everything is OK(Images Add) but when i want to delete an image it's working and delete the image but its delete last one image not specific image which one i want to delete, i don't know how to get position of specific image and delete it.

public class PhotoAdd_Adapter extends PagerAdapter {
    private LayoutInflater inflater;
    private Context context;
    ArrayList<String> mylist;
    SharedPreferences sharedPreferences;
    JSONArray responsearray = null;
    private static final String TAG_PHOTO_ONE = "Gallery_Full";
    HashMap<String, String> get;
    LinearLayout addimages;
    String ImageID;
    ProgressBar progressBar;
    String finalimgpath, imageId;
    ImageView imageView, deletebtn;
    TextView no_image, p_id;
    private FragmentManager f_manager;
    int delPosition;

    public PhotoAdd_Adapter(Context context, ArrayList<String> mylist, FragmentManager f_manager) {
        this.f_manager = f_manager;
        this.context = context;
        this.mylist = mylist;
        inflater = LayoutInflater.from(context);
        sharedPreferences = context.getSharedPreferences(context.getString(R.string.prefs), 0);
    }
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
    }
    @Override
    public int getCount() {
        return mylist.size();
    }
    @Override
    public int getItemPosition(@NonNull Object object) {
        if(mylist.contains(object)){
            return mylist.indexOf(object);
        }else {
            return POSITION_NONE;
        }
//        return super.getItemPosition(object);
//        return PagerAdapter.POSITION_NONE;
    }
    @Override
    public Object instantiateItem(ViewGroup view, final int position) {
        View imageLayout = inflater.inflate(R.layout.photoadd_adapter, view, false);
        assert imageLayout != null;
        imageView = imageLayout.findViewById(R.id.image_adapter);
        deletebtn = imageLayout.findViewById(R.id.deletebtn);
        p_id = imageLayout.findViewById(R.id.p_id);
        this.delPosition = position;       
        String test = String.valueOf(mylist.get(position));
        String finalimgpaths = context.getString(R.string.moreimgpath) + test;
        Glide.with(context)
                .load(finalimgpaths)
                .into(imageView);
        view.addView(imageLayout, 0);
        deletebtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
//                showDialogBox();
                imageId = ImageID;
                Log.e("IMAGEIDONE", imageId);
                mylist.remove(position);
                notifyDataSetChanged();
                responsearray = responsearray(responsearray, position);
                new DeleteImage().execute(true);
            }
        });
        return imageLayout;
    }
    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view.equals(object);
    }
    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
    }
    @Override
    public Parcelable saveState() {
        return null;
    }
    class DeleteImage extends AsyncTask<Boolean, Void, String> {
        @Override
        protected String doInBackground(Boolean... booleans) {
            ProfileApi profileApi = new ProfileApi();
            String result = null;
            try {
                Log.e("IMAGEID", ImageID);
                result = profileApi.deleteImage(sharedPreferences.getString("id", ""), imageId);
                Log.e("DELETERESULT", result);
                JSONObject object = new JSONObject(result);
                if (object.getString("error").equalsIgnoreCase("false")) {

                    return "true";
                } else {
                    String errormsg = object.getString("response");
                    return errormsg;
                }
            } catch (ApiException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }
        @Override
        protected void onPostExecute(String s) {
//            ad.hide();
            super.onPostExecute(s);
            try {
                if (s != null) {
                    Toast.makeText(context, "Image Deleted", Toast.LENGTH_SHORT).show();
                }
            } catch (IllegalStateException e) {
                e.printStackTrace();
            }
        }
    }
    public static JSONArray responsearray(JSONArray jarray, int pos) {
        JSONArray Njarray = new JSONArray();
        try {
            for (int i = 0; i < jarray.length(); i++) {
                if (i != pos)
                    Njarray.put(jarray.get(i));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Njarray;
    }
}

Answer 1

Your problem is that the view pager reloads before the delete image task finishes. So the same set of images are loaded but since the list size has been modified, the last image is not loaded.

Solution: Wait for the delete operation to finish before calling notifyDataSetChanged() on your ViewPager

Answer 2

i have update your code, just try below code:

 public class PhotoAdd_Adapter extends PagerAdapter {
        private LayoutInflater inflater;
        private Context context;
        ArrayList<String> mylist;
        SharedPreferences sharedPreferences;
        JSONArray responsearray = null;
        private static final String TAG_PHOTO_ONE = "Gallery_Full";
        HashMap<String, String> get;
        LinearLayout addimages;
        String ImageID;
        ProgressBar progressBar;
        String finalimgpath, imageId;
        ImageView imageView, deletebtn;
        TextView no_image, p_id;
        private FragmentManager f_manager;
        int delPosition;

        public PhotoAdd_Adapter(Context context, ArrayList<String> mylist, FragmentManager f_manager) {
            this.f_manager = f_manager;
            this.context = context;
            this.mylist = mylist;
            inflater = LayoutInflater.from(context);
            sharedPreferences = context.getSharedPreferences(context.getString(R.string.prefs), 0);
        }
        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View) object);
        }
        @Override
        public int getCount() {
            return mylist.size();
        }
        @Override
        public int getItemPosition(@NonNull Object object) {
            if(mylist.contains(object)){
                return mylist.indexOf(object);
            }else {
                return POSITION_NONE;
            }
    //        return super.getItemPosition(object);
    //        return PagerAdapter.POSITION_NONE;
        }
        @Override
        public Object instantiateItem(ViewGroup view, final int position) {
            View imageLayout = inflater.inflate(R.layout.photoadd_adapter, view, false);
            assert imageLayout != null;
            imageView = imageLayout.findViewById(R.id.image_adapter);
            deletebtn = imageLayout.findViewById(R.id.deletebtn);
            p_id = imageLayout.findViewById(R.id.p_id);
            this.delPosition = position;       
            String test = String.valueOf(mylist.get(position));
            String finalimgpaths = context.getString(R.string.moreimgpath) + test;
            Glide.with(context)
                    .load(finalimgpaths)
                    .into(imageView);
            view.addView(imageLayout, 0);
            deletebtn.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
    //                showDialogBox();
                    imageId = ImageID;
                    Log.e("IMAGEIDONE", imageId);
                    responsearray = responsearray(responsearray, position);
                    new DeleteImage().execute(true);
                }
            });
            return imageLayout;
        }
        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view.equals(object);
        }
        @Override
        public void restoreState(Parcelable state, ClassLoader loader) {
        }
        @Override
        public Parcelable saveState() {
            return null;
        }
        class DeleteImage extends AsyncTask<Boolean, Void, String> {
            @Override
            protected String doInBackground(Boolean... booleans) {
                ProfileApi profileApi = new ProfileApi();
                String result = null;
                try {
                    Log.e("IMAGEID", ImageID);
                    result = profileApi.deleteImage(sharedPreferences.getString("id", ""), imageId);
                    Log.e("DELETERESULT", result);
                    JSONObject object = new JSONObject(result);
                    if (object.getString("error").equalsIgnoreCase("false")) {

                        return "true";
                    } else {
                        String errormsg = object.getString("response");
                        return errormsg;
                    }
                } catch (ApiException e) {
                    e.printStackTrace();
                } catch (JSONException e) {
                    e.printStackTrace();
                }
                return null;
            }
            @Override
            protected void onPostExecute(String s) {
    //            ad.hide();
                super.onPostExecute(s);
                try {
                    if (s != null) {
                        Toast.makeText(context, "Image Deleted",Toast.LENGTH_SHORT).show();
                    mylist.remove(position);
                    notifyDataSetChanged();
                    }
                } catch (IllegalStateException e) {
                    e.printStackTrace();
                }
            }
        }
        public static JSONArray responsearray(JSONArray jarray, int pos) {
            JSONArray Njarray = new JSONArray();
            try {
                for (int i = 0; i < jarray.length(); i++) {
                    if (i != pos)
                        Njarray.put(jarray.get(i));
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            return Njarray;
        }
    }