如何从第一个活动 android studio 中不存在的第二个活动添加新数据？

Question

I have the following data in my Main Activity: Place Image, Place Name, and Place Location. I want to add the Description and Gallery in the Second Activity, but I don't have the data to pass from Main to Second Activity. How to do this? Is it possible to achieve?

Here's my Main Activity

public class MainActivity extends AppCompatActivity {

RecyclerView mainRecycler, mpRecycler;
MainAdapter mainAdapter;
MpAdapter mpAdapter;
EditText searchView;
CharSequence search="";

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

    searchView = findViewById(R.id.search);

    mainRecycler = findViewById(R.id.main_recycler);
    mpRecycler = findViewById(R.id.mp_recycler);
    mainRecycler();
    mpRecycler();
}

private void mainRecycler() {
    mainRecycler.setHasFixedSize(true);
    mainRecycler.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));

    final ArrayList<MainHelperClass> mainLocations = new ArrayList<>();
    mainLocations.add(new MainHelperClass(R.drawable.image1, "Place Name 1", "Loc 1"));
    mainLocations.add(new MainHelperClass(R.drawable.image2, "Place Name 2", "Loc 2"));
    mainLocations.add(new MainHelperClass(R.drawable.image3, "Place Name 3", "Loc 3"));

    mainAdapter = new MainAdapter(mainLocations, getApplicationContext());
    mainRecycler.setAdapter(mainAdapter);

    searchView.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
            mainAdapter.getFilter().filter(charSequence);
            search = charSequence;
        }

        @Override
        public void afterTextChanged(Editable s) {

        }
    });

}

private void mpRecycler() {
    mpRecycler.setHasFixedSize(true);
    mpRecycler.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));

    ArrayList<MpHelperClass> mpLocations = new ArrayList<>();
    mpLocations.add(new MpHelperClass(R.drawable.image1, "Place Name 1", "Loc 1"));
    mpLocations.add(new MpHelperClass(R.drawable.image2, "Place Name 2", "Loc 2"));
    mpLocations.add(new MpHelperClass(R.drawable.image3, "Place Name 3", "Loc 3"));

    mpAdapter = new MpAdapter(mpLocations, getApplicationContext());
    mpRecycler.setAdapter(mpAdapter);
}

public void onClick(View view) {
    Intent intent = new Intent(this, MainDetails.class);
    startActivity(intent);
}
}

Here's my Adapter

public class MainAdapter extends RecyclerView.Adapter<MainAdapter.MainViewHolder> implements Filterable {

ArrayList<MainHelperClass> mainLocations;
ArrayList<MainHelperClass> filteredMainLocations;
Context context;
public MainAdapter(ArrayList<MainHelperClass> mainLocations, Context context) {
    this.mainLocations = mainLocations;
    this.context = context;
    this.filteredMainLocations = mainLocations;
}


@NonNull
@Override
public MainViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.main_card_design,parent,false);
    MainViewHolder mainViewHolder = new MainViewHolder(view);
    return mainViewHolder;
}

@Override
public void onBindViewHolder(@NonNull MainViewHolder holder, int position) {

    final MainHelperClass mainHelperClass = filteredMainLocations.get(position);
    holder.image.setImageResource(mainHelperClass.getImage());
    holder.placeName.setText(mainHelperClass.getPlaceName());
    holder.location.setText(mainHelperClass.getLocation());

    holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(context, MainDetails.class);
            intent.putExtra("image", mainHelperClass.getImage());
            intent.putExtra("place name", mainHelperClass.getPlaceName());
            intent.putExtra("location", mainHelperClass.getLocation());
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(intent);
        }
    });
}

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

public static class MainViewHolder extends RecyclerView.ViewHolder{

    ImageView image;
    TextView placeName, location;

    public MainViewHolder(@NonNull View itemView) {
        super(itemView);
        image = itemView.findViewById(R.id.main_image);
        placeName = itemView.findViewById(R.id.main_place_name);
        location = itemView.findViewById(R.id.main_location);
    }
}

   public Filter getFilter() {
    return new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence charSequence) {

            String key = charSequence.toString();
            if (key.isEmpty()) {
                filteredMainLocations = mainLocations;
            }else {
                ArrayList<MainHelperClass> isFiltered = new ArrayList<>();
                for (MainHelperClass row : mainLocations) {
                    if (row.getPlaceName().toLowerCase().contains(key.toLowerCase())) {
                        isFiltered.add(row);
                    }
                }

                filteredMainLocations = isFiltered;
            }

            FilterResults filterResults = new FilterResults();
            filterResults.values = filteredMainLocations;
            return filterResults;
        }

        @Override
        protected void publishResults(CharSequence constraint, 
FilterResults filterResults) {
            filteredMainLocations = (ArrayList<MainHelperClass>) 
filterResults.values;
            notifyDataSetChanged();
        }
    };
   }
   }

Here's my Second Activity

public class MainDetails extends AppCompatActivity {
ImageView image;
TextView placeName, location;

RecyclerView.Adapter adapter;

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

    image = (ImageView)findViewById(R.id.main_image_details);
    placeName = (TextView)findViewById(R.id.main_place_name_details);
    location = (TextView)findViewById(R.id.main_loc_details);

 image.setImageResource(getIntent().getIntExtra("image", 0));
    placeName.setText(getIntent().getStringExtra("place name"));
    location.setText(getIntent().getStringExtra("location"));

}

}

Answer 1

Use bundle to pass data to the second activity. First, When you want to start your second activity write this:

Intent intent = new Intent(context, MainDetails.class);
intent.putExtra("mylist", mainLocations);
startActivity(intent);

Then, In MainDetails class get your bundle:

ArrayList< MainHelperClass > myList = (ArrayList< MainHelperClass >)getIntent().getSerializableExtra("mylist");

*Don't forget to implement Serializable in your MainHelperClass class.