使用 MutableLiveData 和具有多个图像的 LiveData 实现 ViewModel

Question

下面的代码使我能够从手机图片库中最多选择 4 张图片。但是，我需要有关视图模型代码的帮助。如果选择了一张图像并且手机配置发生了变化，则该图像会保留下来。但是，如果选择了多张图像，则只有一张图像会保留，所有其他图像都会消失。我需要帮助才能知道我在 viewmodel 代码上做错了什么。在没有视图模型的情况下，所有其他代码都按预期运行良好。添加视图模型以在手机配置更改时为图像添加持久性。我在下面附上了我的代码。

这是选择图像的java代码

'''    
public class MakingFamzFragment extends Fragment {

    ActivityResultLauncher<PickVisualMediaRequest> pickMedia = registerForActivityResult(new ActivityResultContracts.PickMultipleVisualMedia(4),
            new ActivityResultCallback<List<Uri>>() {
        @Override
        public void onActivityResult(List<Uri> result) {

            Intent intent = new Intent();
            Intent intent2 = new Intent();
            Intent intent3 = new Intent();
            Intent intent4 = new Intent();

            if(result.size() == 1){
                // Code for when only one picture is picked
                //Capturing the activity result Uri in the Intent
                intentOne = intent.setData(result.get(0));
                //Create ContentResolver to convert the Uri to Bitmap
                cr = requireContext().getContentResolver();
                try {
                    bitmapOne = MediaStore.Images.Media.getBitmap(cr, intentOne.getData());
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (isbitmapOne(bitmapOne)) {
                    //Capturing the first image in ImageViewOne using Glide
                    ImageViewOne = binding.editBeforePostingOne;
                    ImageViewOne.setImageBitmap(bitmapOne);
                    Glide.with(requireActivity())
                            .load(bitmapOne)
                            .centerCrop()
                            .into(ImageViewOne);
                    ImageViewOne.setVisibility(View.VISIBLE);
                    viewModel.setImageL(Collections.singletonList(bitmapOne));
                }

            }else if(result.size() == 2){

                // Codes for only when two pictures are picked
                intentOne = intent.setData(result.get(0));
                intentTwo = intent2.setData(result.get(1));
                //Create ContentResolver to convert the Uris to Bitmap
                cr = requireContext().getContentResolver();
                try {
                    bitmapOne = MediaStore.Images.Media.getBitmap(cr, intentOne.getData());
                    bitmapTwo = MediaStore.Images.Media.getBitmap(cr, intentTwo.getData());
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (isbitmapOne(bitmapOne) && isbitmapTwo(bitmapTwo)) {
                    //Capturing the first image in ImageViewOne using Glide
                    ImageViewOne = binding.editBeforePostingOne;
                    ImageViewOne.setImageBitmap(bitmapOne);
                    Glide.with(requireActivity())
                            .load(bitmapOne)
                            .centerCrop()
                            .into(ImageViewOne);
                    ImageViewOne.setVisibility(View.VISIBLE);
                   viewModel.setImageL(Collections.singletonList(bitmapOne));

                    //Capturing the second image in ImageViewTwo using Glide
                    ImageViewTwo = binding.editBeforePostingTwo;
                    ImageViewTwo.setImageBitmap(bitmapTwo);
                    Glide.with(requireActivity())
                            .load(bitmapTwo)
                            .centerCrop()
                            .into(ImageViewTwo);
                    ImageViewTwo.setVisibility(View.VISIBLE);
                   viewModel.setImageL(Collections.singletonList(bitmapTwo));
                }

            }else if(result.size() == 3){
                //Codes for only when three pictures are picked
                intentOne = intent.setData(result.get(0));
                intentTwo = intent2.setData(result.get(1));
                intentThree = intent3.setData(result.get(2));
                //Create ContentResolver to convert the Uris to Bitmap
                cr = requireContext().getContentResolver();
                try {
                    bitmapOne = MediaStore.Images.Media.getBitmap(cr, intentOne.getData());
                    bitmapTwo = MediaStore.Images.Media.getBitmap(cr, intentTwo.getData());
                    bitmapThree = MediaStore.Images.Media.getBitmap(cr, intentThree.getData());
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (isbitmapOne(bitmapOne) && isbitmapTwo(bitmapTwo) && isbitmapThree(bitmapThree)) {
                    //Capturing the first image in ImageViewOne using Glide
                    ImageViewOne = binding.editBeforePostingOne;
                    ImageViewOne.setImageBitmap(bitmapOne);
                    Glide.with(requireActivity())
                            .load(bitmapOne)
                            .centerCrop()
                            .into(ImageViewOne);
                    ImageViewOne.setVisibility(View.VISIBLE);
                   viewModel.setImageL(Collections.singletonList(bitmapOne));

                    //Capturing the second image in ImageViewThree using Glide
                    ImageViewTwo = binding.editBeforePostingTwo;
                    ImageViewTwo.setImageBitmap(bitmapTwo);
                    Glide.with(requireActivity())
                            .load(bitmapTwo)
                            .centerCrop()
                            .into(ImageViewTwo);
                    ImageViewTwo.setVisibility(View.VISIBLE);
                  viewModel.setImageL(Collections.singletonList(bitmapTwo));

                    //Capturing the third image in ImageViewThree using Glide
                    ImageViewThree = binding.editBeforePostingThree;
                    ImageViewThree.setImageBitmap(bitmapThree);
                    Glide.with(requireActivity())
                            .load(bitmapThree)
                            .centerCrop()
                            .into(ImageViewThree);
                    ImageViewThree.setVisibility(View.VISIBLE);
                    viewModel.setImageL(Collections.singletonList(bitmapThree));
                }

            }

        }
        });
    

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

        //Instantiatiate the binding class
        binding = FragmentMakingFamzBinding.inflate(getLayoutInflater());

        //Instantiate the viewModel class
        viewModel = new ViewModelProvider(this.requireActivity()).get(MyViewModel.class);

        // binding the multiautocompletetextiview as famzMakinglayout and implement the textcount found in it
        //to count the number of text typed in it
        fmzMakingLayout = binding.multiAutocompleteTextview;
        textCount = binding.textCount;
        fmzMakingLayout.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                ch = String.valueOf(fmzMakingLayout.getText().toString().length());
                textCount.setText(ch);
                System.out.println(ch);
            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });

        return binding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        viewModel.getImage().observe(getViewLifecycleOwner(), new Observer<List<Bitmap>>() {
            @Override
            public void onChanged(List<Bitmap> bitmap) {
                if(bitmap.size() == 1){

                bitmapOne = bitmap.get(0);

                ImageViewOne = binding.editBeforePostingOne;
                ImageViewOne.setImageBitmap(bitmapOne);
                Glide.with(requireContext())
                        .load(bitmapOne)
                        .centerCrop()
                        .into(ImageViewOne);
                ImageViewOne.setVisibility(View.VISIBLE);

                }else if(bitmap.size() == 2) {

                    bitmapOne = bitmap.get(0);

                    ImageViewOne = binding.editBeforePostingOne;
                    ImageViewOne.setImageBitmap(bitmapOne);
                    Glide.with(requireContext())
                            .load(bitmapOne)
                            .centerCrop()
                            .into(ImageViewOne);
                    ImageViewOne.setVisibility(View.VISIBLE);

                    bitmapTwo = bitmap.get(1);

                    ImageViewTwo = binding.editBeforePostingTwo;
                    ImageViewTwo.setImageBitmap(bitmapTwo);
                    Glide.with(requireContext())
                            .load(bitmapTwo)
                            .centerCrop()
                            .into(ImageViewTwo);
                    ImageViewTwo.setVisibility(View.VISIBLE);
                }



            }
        });


        binding.famzingBottomNavigation.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {

            @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                // Defining local final ids
                final int id1 = R.id.famzing_add_pictures;
                final int id2 = R.id.famzing_files;
                final int id3 = R.id.famzing_emoji;
                final int id4 = R.id.famzing_giff;

                switch (item.getItemId()) {
                    case id1:
                        Intent iGallery = new Intent(Intent.ACTION_PICK);
                        iGallery.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "image/*");
                        iGallery.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
                        pickMedia.launch(pick);

                        Toast.makeText(getContext(), "Add picture selected", Toast.LENGTH_SHORT).show();
                        break;
                    case id2:
                        Toast.makeText(getContext(), "Add files selected", Toast.LENGTH_SHORT).show();
                        break;
                    case id3:
                        Toast.makeText(getContext(), "Add emoji selected", Toast.LENGTH_SHORT).show();
                        break;
                    case id4:
                        Toast.makeText(getContext(), "Add giff selected", Toast.LENGTH_SHORT).show();
                        break;
                }

                return false;
            }
        });
    }
}
'''

This is the viewmodel code
---------------------------

'''

public class MyViewModel extends ViewModel {

    public MutableLiveData<List<Bitmap>> imageL = new MutableLiveData<>();

    public void setImageL(List<Bitmap> bitmapOne){
        imageL.postValue(bitmapOne);

    }

    public LiveData<List<Bitmap>> getImage(){
        return imageL;
    }


    @Override
    protected void onCleared() {
        super.onCleared();
    }
}

'''

这是包含图像视图的片段的 xml 代码

发送到

'''
<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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:id="@+id/famz_making_page"
    android:layout_width="match_parent"

    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"

    android:background="@color/white"

    android:orientation="vertical"
    tools:context=".MakingFamzFragment">

    <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="90dp"
        android:gravity="top"
        android:orientation="horizontal"
        android:padding="9dp">

        <ImageView
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:layout_marginStart="9dp"
            android:layout_marginLeft="9dp"
            android:background="@mipmap/user_profile_image"
            android:contentDescription="@string/profile_picture"
            android:gravity="end">

        </ImageView>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="start"
                android:layout_marginStart="9dp"
                android:layout_marginLeft="9dp"
                android:text="@string/profile_name"
                android:textSize="12sp">

            </TextView>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="start|bottom"
                android:layout_marginStart="9dp"
                android:layout_marginLeft="9dp"
                android:layout_marginBottom="6dp"
                android:text="@string/profile_username"
                android:textSize="12sp">

            </TextView>
        </LinearLayout>


    </LinearLayout>


    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_marginTop="2dp"
        android:background="?android:attr/listDivider">

    </View>
  
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="@color/pink"
                android:orientation="vertical">


                <TextView

                    android:id="@+id/text_count"
                    android:layout_width="39dp"
                    android:layout_height="15dp"
                    android:layout_gravity="end"
                    android:layout_marginTop="2dp"
                    android:layout_marginEnd="9dp"
                    android:layout_marginRight="9dp">

                </TextView>

                <MultiAutoCompleteTextView
                    android:id="@+id/multi_autocomplete_textview"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_margin="6dp"
                    android:autoLink="all"
                    android:background="@color/transparent"
                    android:bufferType="normal"
                    android:fitsSystemWindows="true"
                    android:fontFamily="sans-serif"
                    android:hint="@string/write_here"
                    android:linksClickable="true"
                    android:maxLength="500"
                    android:padding="8dp"
                    android:selectAllOnFocus="true"
                    android:textColorLink="#2596be"
                    android:textSize="16sp"
                    tools:ignore="TouchTargetSizeCheck">

                </MultiAutoCompleteTextView>

                <HorizontalScrollView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content">


                <RelativeLayout

                    android:id="@+id/relate_make_post_frag"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="horizontal">

                    <ImageView
                        android:layout_width="200dp"
                        android:layout_height="150dp"
                        android:id="@+id/edit_Before_Posting_One"
                        android:contentDescription="@string/image_number_one"
                        android:layout_alignParentLeft="true"
                        android:layout_alignParentStart="true"
                        android:layout_marginStart="2dp"
                        android:layout_marginLeft="2dp"
                        android:layout_marginEnd="2dp"
                        android:layout_marginRight="2dp"
                        android:visibility="gone"/>
                    <ImageView
                        android:layout_width="200dp"
                        android:layout_height="150dp"
                        android:id="@+id/edit_Before_Posting_Two"
                        android:contentDescription="@string/image_number_two"
                        android:layout_toRightOf="@id/edit_Before_Posting_One"
                        android:layout_toEndOf="@id/edit_Before_Posting_One"
                        android:layout_marginStart="2dp"
                        android:layout_marginLeft="2dp"
                        android:layout_marginEnd="2dp"
                        android:layout_marginRight="2dp"
                        android:visibility="gone"/>
                    <ImageView
                        android:layout_width="200dp"
                        android:layout_height="150dp"
                        android:id="@+id/edit_Before_Posting_three"
                        android:contentDescription="@string/image_number_three"
                        android:layout_toRightOf="@id/edit_Before_Posting_Two"
                        android:layout_toEndOf="@id/edit_Before_Posting_Two"
                        android:layout_marginStart="2dp"
                        android:layout_marginLeft="2dp"
                        android:layout_marginEnd="2dp"
                        android:layout_marginRight="2dp"
                        android:visibility="gone"/>
                    <ImageView
                        android:layout_width="200dp"
                        android:layout_height="150dp"
                        android:id="@+id/edit_Before_Posting_Four"
                        android:contentDescription="@string/image_number_four"
                        android:layout_toRightOf="@id/edit_Before_Posting_three"
                        android:layout_toEndOf="@id/edit_Before_Posting_three"
                        android:layout_marginStart="2dp"
                        android:layout_marginLeft="2dp"
                        android:layout_marginEnd="2dp"
                        android:layout_marginRight="2dp"
                        android:visibility="gone"/>

                </RelativeLayout>

                </HorizontalScrollView>


                <View
                    android:layout_width="wrap_content"
                    android:layout_height="1dp"
                    android:layout_marginTop="2dp"
                    android:background="?android:attr/listDivider">

                </View>

            </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:foregroundGravity="top"
                android:background="@color/white">

                <com.google.android.material.bottomnavigation.BottomNavigationView
                    android:id="@+id/famzing_bottom_navigation"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:background="@drawable/makingfamz_elevation"
                    android:fitsSystemWindows="true"
                    app:elevation="7dp"
                    app:itemIconTint="@color/fambuk_green"
                    app:itemTextColor="@color/fambuk_green"
                    app:menu="@menu/famz_making_menu">

                </com.google.android.material.bottomnavigation.BottomNavigationView>

            </LinearLayout>

            <View
                android:layout_width="wrap_content"
                android:layout_height="1dp"
                android:layout_marginTop="2dp"
                android:background="?android:attr/listDivider">

            </View>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal">

                <Button
                    style="?android:attr/buttonBarButtonStyle"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginEnd="4dp"
                    android:layout_marginRight="0.1dp"
                    android:layout_weight="2"
                    android:background="@drawable/submit_post_button_elevation"
                    android:text="@string/post_submit_button"
                    android:textColor="@color/white">

                </Button>

                <Button
                    style="?android:attr/buttonBarButtonStyle"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center_horizontal"
                    android:layout_marginStart="0.1dp"
                    android:layout_marginLeft="0.1dp"
                    android:layout_weight="2"
                    android:background="@drawable/submit_post_button_elevation"
                    android:text="@string/close_button"
                    android:textColor="@color/white">

                </Button>
            </LinearLayout>

    <View
        android:layout_width="wrap_content"
        android:layout_height="1dp"
        android:layout_marginTop="2dp"
        android:background="?android:attr/listDivider">

    </View>

</LinearLayout>


</ScrollView>

'''

这是一张图片被选中时的屏幕截图，当手机旋转时会发生什么

注意：当只选择一张图像时，viewmodel 工作正常。 However, when more than one image is selected, the viewmodel does not work properly. 当我选择两个不同的图像时，出现的两个图像是最后一个被选择的图像。第一个没有出现。当它旋转到横向模式时，一个图像消失，片段上只剩下一个。以下是示例屏幕截图：

How can I write the viewmodel code so that when more than one images are picked and the orientation of the phone is changed, all picked images will not disappear from the phone.