如何使用开关根据字符串在CardViews中对RecyclerView进行排序？

Question

我想按字母顺序或按受欢迎程度来订购一个基于开关的充满RecyclerView的cardViews，这是我迄今为止所做的：

 public class CategoriesRecyclerView extends Activity {
            private List<Categories> categories;
            private RecyclerView rv;
            private Switch categoriesSortingSwitch;
            private TextView switchStatus;



@Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);


            setContentView(R.layout.categories_recycler_view);


            rv = (RecyclerView) findViewById(R.id.cardList);
            rv.setHasFixedSize(true);
            LinearLayoutManager llm = new LinearLayoutManager(this);
            llm.setOrientation(LinearLayoutManager.VERTICAL);
            rv.setLayoutManager(llm);

            //HERE I CALL THE METHOD THAT INITIALIZE ALL THE CARDVIEWS WITH IT'S ELEMENTS ISIDE THE RECYCLERVIEW
            initializeData();

            CategoriesAdapter ca = new CategoriesAdapter(categories);
            rv.setAdapter(ca);


            //SWITCH IMPLEMENTATION FOR THE SORTING
            categoriesSortingSwitch = (Switch) findViewById(R.id.switchsortcategories);
            switchStatus = (TextView) findViewById(R.id.testswitch);
            //set the switch to OFF
            categoriesSortingSwitch.setChecked(false);
            //attach a listener to check for changes in state
            categoriesSortingSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {



                       if(isChecked){
    //HERE I SHOW A TEXT VIEW WITH THE SWITCH STATUS (WORKS FINE)
                            switchStatus.setText("Sorting alphabetically");



    //HERE I TRY TO ADD ELEMENTS TO THE LIST categories ORGANIZED BY THEIR NAME

                        categories.add(new Categories("CARS", "CARS"));
                        categories.add(new Categories("COUSINE", "COUSINE"));
                        categories.add(new Categories("GAMBLING", "GAMBLING"));
                        categories.add(new Categories("GAMING", "GAMING"));
                        categories.add(new Categories("HISTORY", "HISTORY"));
                        categories.add(new Categories("MUSIC", "MUSIC"));
                        categories.add(new Categories("NATURE", "NATURE"));
                        categories.add(new Categories("RANDOM", "RANDOM"));
                        categories.add(new Categories("SPORTS", "SPORTS"));
                        categories.add(new Categories("STUDIES", "STUDIES"));
                        categories.add(new Categories("TECH", "TECH"));




                    }else{
                        switchStatus.setText("Sorting by popularity");


     //HERE I TRY TO ADD ELEMENTS TO THE LIST categories ORGANIZED BY THEIR POPULARITY


                        categories.add(new Categories("CARS", "CARS"));
                        categories.add(new Categories("SPORTS", "SPORTS"));
                        categories.add(new Categories("GAMING", "GAMING"));
                        categories.add(new Categories("GAMBLING", "GAMBLING"));
                        categories.add(new Categories("TECH", "TECH"));
                        categories.add(new Categories("NATURE", "NATURE"));
                        categories.add(new Categories("RANDOM", "RANDOM"));
                        categories.add(new Categories("COUSINE", "COUSINE"));
                        categories.add(new Categories("HISTORY", "HISTORY"));
                        categories.add(new Categories("MUSIC", "MUSIC"));
                        categories.add(new Categories("STUDIES", "STUDIES"));
                    }

                }
            });


            //check the current state before we display the screen
            if(categoriesSortingSwitch.isChecked()){
                switchStatus.setText("Sorting alphabetically");



                categories.add(new Categories("CARS", "CARS"));
                categories.add(new Categories("COUSINE", "COUSINE"));
                categories.add(new Categories("GAMBLING", "GAMBLING"));
                categories.add(new Categories("GAMING", "GAMING"));
                categories.add(new Categories("HISTORY", "HISTORY"));
                categories.add(new Categories("MUSIC", "MUSIC"));
                categories.add(new Categories("NATURE", "NATURE"));
                categories.add(new Categories("RANDOM", "RANDOM"));
                categories.add(new Categories("SPORTS", "SPORTS"));
                categories.add(new Categories("STUDIES", "STUDIES"));
                categories.add(new Categories("TECH", "TECH"));


            }
            else {
                switchStatus.setText("Sorting by popularity");






                categories.add(new Categories("CARS", "CARS"));
                categories.add(new Categories("SPORTS", "SPORTS"));
                categories.add(new Categories("GAMING", "GAMING"));
                categories.add(new Categories("GAMBLING", "GAMBLING"));
                categories.add(new Categories("TECH", "TECH"));
                categories.add(new Categories("NATURE", "NATURE"));
                categories.add(new Categories("RANDOM", "RANDOM"));
                categories.add(new Categories("COUSINE", "COUSINE"));
                categories.add(new Categories("HISTORY", "HISTORY"));
                categories.add(new Categories("MUSIC", "MUSIC"));
                categories.add(new Categories("STUDIES", "STUDIES"));
            }

        }

    //HERE IS THE initializeData() METHOD THAT I CALLED BEFORE THAT HAS A NEW LIST THAT SUPPOSEDLY WAS FILLED ALPHABETICALLY OR BY POPULARITY BASED ON THE SWITCH STATUS.

        private void initializeData() {


            categories = new ArrayList<>();

        }
    }

此时它编译并运行，当切换状态被更改时，它会在TextView上正确地通知它我为此创建的，但是RecyclerView的元素没有发生任何变化，它们只是因为某种原因而保持相同的顺序。

基本上，要做的是按照开关指定的顺序将元素直接添加到在方法initializeData()中创建的列表中。

我怎么才能让这一切按我想要的方式运作呢？我没有使用排序算法，因为数据非常小。

Answer 1

您可能需要使用比较器对Categories进行排序，然后将排序列表设置为启用CardView的适配器，然后使用notifyDataSetChanged()通知适配器。

本教程将有助于如何使用Comparator的。