单击项目时将数据从 RecyclerView 传递到 Fragment

Question

I am currently implementing a Food Diary which doesn't seem to be functioning properly at the moment, upon opening the RecyclerView when the user clicks on an Item the Toast message is displayed appropriately and they navigated back to the fragment page. However I would like to pass the data which they clicked on to the previous fragment and set a TextView appropriately with the item they selected, please see code below:

public class InputFoodToDiary extends AppCompatActivity {
RecyclerView recyclerView;
UserDatabase userDatabase;
ArrayList<String> FoodID, FoodName, Calories;

CustomAdapter customAdapter;

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

    recyclerView = findViewById(R.id.recyclerView_InputFood);

    userDatabase = new UserDatabase(InputFoodToDiary.this, "CALTOR", null, 1);

    FoodID = new ArrayList<>();
    FoodName = new ArrayList<>();
    Calories = new ArrayList<>();

    storeDataInArrays();

    customAdapter = new CustomAdapter(InputFoodToDiary.this, FoodID, FoodName, Calories, new CustomAdapter.OnItemClickListener() {
        @Override
        public void onItemClick(View view, int position) {
            Toast.makeText(getApplicationContext(), Calories.get(position), Toast.LENGTH_SHORT).show();
            onBackPressed();
        }
    });
    recyclerView.setAdapter(customAdapter);
    recyclerView.setLayoutManager(new LinearLayoutManager(InputFoodToDiary.this));
}

void storeDataInArrays(){
    Cursor cursor = userDatabase.readAllData();
    if(cursor.getCount() == 0){
        Toast.makeText(this, "No Data.", Toast.LENGTH_SHORT).show();
    } else {
        while (cursor.moveToNext()){
            FoodID.add(cursor.getString(0));
            FoodName.add(cursor.getString(1));
            Calories.add(cursor.getString(2));
        }
    }
}

public void onBackPressed(){
    super.onBackPressed();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.food_search, menu);

    MenuItem searchItem = menu.findItem(R.id.action_search);
    SearchView searchView = (SearchView)searchItem.getActionView();

    searchView.setImeOptions(EditorInfo.IME_ACTION_DONE);

    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {
            customAdapter.getFilter().filter(newText);
            return false;
        }
    });
    return true;
}

}

Answer 1

From what I see you don't use fragments, you are using activity. When back press is called from an activity it closes itself. The solution would be to have the recycler view in a fragment under your activity and when you click the item in the recycler view, save the data in a member of the parent activity, than when the fragment disapear, the data will be saved in the parent activity and you can do whatever you want with it.