Блог

Я хочу реализовать просмотр с несколькими вариантами выбора и сохранить выбранные элементы и их состояние в базе данных телефона либо sqlite, либо sharedpreference(если возможно) и извлечь его в выбранном состоянии. при выборе категории ее фон становится синим, но когда вы возвращаетесь к активности, он остается белым.

Вот мой код

Класс адаптера

 public class BlogCategoryAdapter extends RecyclerView.Adapter<BlogCategoryAdapter.BlogCategoryViewHolder> {


List<BlogCategoryModel> blogCategoryModelList;

public BlogCategoryAdapter( List<BlogCategoryModel> blogCategoryModelList) {
    this.blogCategoryModelList = blogCategoryModelList;
}

@NonNull
@NotNull
@Override
public BlogCategoryViewHolder onCreateViewHolder(@NonNull @NotNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.category_item_layout, parent, false);
    return new BlogCategoryViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull @NotNull BlogCategoryViewHolder holder, int position) {
    holder.bindBlogCategory(blogCategoryModelList.get(position));
}

@Override
public int getItemCount() {
    return blogCategoryModelList.size();
}

public List<BlogCategoryModel> getSelectedBlogCategory(){
    List<BlogCategoryModel> selectedBlogCategory = new ArrayList<>();
    for (BlogCategoryModel blogCategoryModel : blogCategoryModelList){
        if (blogCategoryModel.getSelected()){
            selectedBlogCategory.add(blogCategoryModel);
        }
    }
    return selectedBlogCategory;
}

public class BlogCategoryViewHolder extends RecyclerView.ViewHolder{

    TextView blogTopic;
    public BlogCategoryViewHolder(@NonNull @NotNull View itemView) {
        super(itemView);
        blogTopic = itemView.findViewById(R.id.category_item_text);
    }

    // Bind data
    void bindBlogCategory(final BlogCategoryModel blogCategoryModel){
        blogTopic.setText(blogCategoryModel.getBlogTopic());
        blogTopic.setBackgroundResource(blogCategoryModel.getSelected() ?
                R.drawable.category_item_selected_bg : R.drawable.category_item_default_bg);
        blogTopic.setTextColor(blogCategoryModel.getSelected() ? Color.WHITE : Color.BLACK);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                blogCategoryModel.setSelected(!blogCategoryModel.getSelected());
                blogTopic.setBackgroundResource(blogCategoryModel.getSelected() ? R.drawable.category_item_selected_bg : R.drawable.category_item_default_bg);
                blogTopic.setTextColor(blogCategoryModel.getSelected() ? Color.WHITE : Color.BLACK);

            }
        });
    }

}
 

Класс SharedPreference

 public class PrefConfig {

private static final String PREFERENCE_NAME = "saved_category";
private static final String PREFERENCE_KEY = "pref_key";

public static void saveSelectedBlogCategoryInPref(Context context, List<BlogCategoryModel> selectedBlogCategory) {
    Gson gson = new Gson();
    String jsonString = gson.toJson(selectedBlogCategory);

    SharedPreferences preferences = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = preferences.edit();
    editor.putString(PREFERENCE_KEY, jsonString);
    editor.apply();

}

public static List<BlogCategoryModel> fetchSelectedBlogCategoryFromPref(Context context)  {
    SharedPreferences preferences = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
    Gson gson = new Gson();
    String jsonString = preferences.getString(PREFERENCE_KEY, null);
    Type type = new TypeToken<ArrayList<BlogCategoryModel>>() {}.getType();
    return gson.fromJson(jsonString, type);

}
 

}

Model class

 public class BlogCategoryModel implements Serializable  {
private String blogTopic;
private Boolean isSelected = false;

public BlogCategoryModel() {
}

public BlogCategoryModel(String blogTopic, Boolean isSelected) {
    this.blogTopic = blogTopic;
    this.isSelected = isSelected;
}

public String getBlogTopic() {
    return blogTopic;
}

public void setBlogTopic(String blogTopic) {
    this.blogTopic = blogTopic;
}

public Boolean getSelected() {
    return isSelected;
}

public void setSelected(Boolean selected) {
    isSelected = selected;
}
 

}

Активность

 public class BlogCategoryActivity extends AppCompatActivity{

List<BlogCategoryModel> blogCategoryModelList;
FloatingActionButton fabSaveCategories;
BlogCategoryAdapter blogCategoryAdapter;
List<BlogCategoryModel> getSelectedDataList;
ListView selectedCategoryListView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_blog_category);

    fabSaveCategories = findViewById(R.id.floatingActionButton);

    selectedCategoryListView = findViewById(R.id.selected_category_listview);

    getSelectedDataList = PrefConfig.fetchSelectedBlogCategoryFromPref(this);
    Log.d("TAG", "getData: "   PrefConfig.fetchSelectedBlogCategoryFromPref(this));
    if (getSelectedDataList == null) {
        getSelectedDataList = new ArrayList<>();
    }

    ArrayAdapter<BlogCategoryModel> arrayAdapter = new ArrayAdapter<>(this,R.layout.category_item_layout, getSelectedDataList);

    selectedCategoryListView.setAdapter(arrayAdapter);



    initViews();
    getBlogTopic();

    fabSaveCategories.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            List<BlogCategoryModel> selectedBlogCategory = blogCategoryAdapter.getSelectedBlogCategory();
            PrefConfig.saveSelectedBlogCategoryInPref(getApplicationContext(), selectedBlogCategory);

            Log.d("TAG", "onClick: "   selectedBlogCategory);

            StringBuilder selectedNames = new StringBuilder();
            for (int i = 0; i < selectedBlogCategory.size(); i  ) {
                selectedNames.append(selectedBlogCategory.get(i).getBlogTopic());
                selectedNames.append("n");
            }
            Toast.makeText(BlogCategoryActivity.this, ""   selectedNames.toString().trim(), Toast.LENGTH_SHORT).show();


        }
    });

}

@Override
protected void onResume() {
    super.onResume();
    getSelectedDataList = PrefConfig.fetchSelectedBlogCategoryFromPref(this);
    Log.d("TAG", "getData: "   PrefConfig.fetchSelectedBlogCategoryFromPref(this));
    if (getSelectedDataList == null) {
        getSelectedDataList = new ArrayList<>();
    }
}

private void getBlogTopic() {
    blogCategoryModelList = new ArrayList<>();
    FirebaseFirestore firebaseFirestore = FirebaseFirestore.getInstance();
    RecyclerView blogCategoryRecyclerView = findViewById(R.id.blog_category_recyclerview);
    blogCategoryRecyclerView.setHasFixedSize(true);

    FlexboxLayoutManager flexboxLayoutManager = new FlexboxLayoutManager(this);
    flexboxLayoutManager.setFlexDirection(FlexDirection.ROW);
    flexboxLayoutManager.setJustifyContent(JustifyContent.CENTER);
    blogCategoryRecyclerView.setLayoutManager(flexboxLayoutManager);
    blogCategoryAdapter = new BlogCategoryAdapter(blogCategoryModelList);
    blogCategoryRecyclerView.setAdapter(blogCategoryAdapter);

    firebaseFirestore.collection("Blog Category")
            .get()
            .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull @NotNull Task<QuerySnapshot> task) {
                    if (task.isSuccessful()){
                        blogCategoryModelList.clear();
                        for (DocumentSnapshot documentSnapshot : task.getResult()){
                            BlogCategoryModel blogCategoryModel = documentSnapshot.toObject(BlogCategoryModel.class);
                            blogCategoryModelList.add(blogCategoryModel);
                        }
                        blogCategoryAdapter.notifyDataSetChanged();
                    }
                }
            });
}