(mainActifity)fragment --> 使用接口从列表传递对象的新片段

Question

我有两件事有问题。

不知何故我无法让我的界面 onClickListener 工作。
在第一个问题解决后，我不知道如何开始fragmentB展示这本书（fragmentA有RecycleView有书）

我是否检查并尝试了 stack/google 上的解决方案？

是的，过去 2 天我一直在努力解决这些问题。有些代码很旧，有些我不知道如何在我的代码中实现它，因为我还是个初学者。

FragmentA(mangasSearch)是MainActivity的一部分（不知道你要不要看MainActivity的代码）

FragmentB 将是一个新的片段，当被按下时，将被销毁并返回到 fragmentA

这是我的RecycleView

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.squareup.picasso.Picasso;

import java.util.ArrayList;

import Classes.Manga;

public class MyAdapterRecyclerView extends RecyclerView.Adapter<MyAdapterRecyclerView.MyViewHolder> {
    private ArrayList<Manga> mDataSet;
    private Context context;

    public MyAdapterRecyclerView(ArrayList<Manga> dataSet, Context context) {
        mDataSet = dataSet;
        this.context = context;
    }

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

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycleview_item, parent, false);
        //  final RecyclerView.ViewHolder holder = new MyViewHolder(view);

        return new MyViewHolder(view);//, communicator);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        Picasso.get().load(mDataSet.get(position).getPosterPicture()).into(holder.imageviewBookCover);
        holder.tvBookTitle.setText("This is book nr: " + position + " and title " + mDataSet.get(position).getTitle());
    }

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


    private static OnMangaBookClickListener onMangaBookClickListener;

    public static class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public ImageView imageviewBookCover;
        public TextView tvBookTitle;
        OnMangaBookClickListener onMangaBookClickListener;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            imageviewBookCover = itemView.findViewById(R.id.imageView_bookcover);
            tvBookTitle = itemView.findViewById(R.id.textView_booktitle);

            itemView.setOnClickListener((View.OnClickListener) onMangaBookClickListener);
        }

        @Override
        public void onClick(View view) {
            onMangaBookClickListener.onMangaBookClick(getAdapterPosition(), view);
        }
    }

    public void setOnMangaBookClickListener(OnMangaBookClickListener onMangaBookClickListener) {
        MyAdapterRecyclerView.onMangaBookClickListener = onMangaBookClickListener;
    }

    public interface OnMangaBookClickListener {
        void onMangaBookClick(int position, View view);
    }
}

这里我做了界面，所以我在fragmentA上调用它并创建FragmentB。

这是fragmentA代码

import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;

import Classes.JsonHandling;
import Classes.Manga;

public class MangasSearchFragment extends Fragment {

    private RecyclerView recyclerView;
    private MyAdapterRecyclerView mAdapter;
    private RecyclerView.LayoutManager layoutManager;
    private Bundle results;
    private ArrayList<Manga> mangaTempList;


    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_mangas_to_search, container, false);
        Context context = getActivity();
        recyclerView = view.findViewById(R.id.recyclerview_manga_book);
        mangaTempList = new JsonHandling(context).getMangaBookJson();

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        recyclerView.setHasFixedSize(true);

        // use a linear layout manager
        layoutManager = new LinearLayoutManager(context);
        recyclerView.setLayoutManager(new GridLayoutManager(context, 3));

        // specify an adapter (see also next example)
        mAdapter = new MyAdapterRecyclerView(mangaTempList, context);

        mAdapter.setOnMangaBookClickListener(new MyAdapterRecyclerView.OnMangaBookClickListener() {
            @Override
            public void onMangaBookClick(int position, View view) {
                Toast.makeText(getContext(), "WHAT?!", Toast.LENGTH_SHORT).show();
            }
        });

        recyclerView.setAdapter(mAdapter);

        return view;
    }
}

Answer 1

对于 onClickListener，您可以在适配器中创建一个接口，并使 Fragment 实现它并将其传递给适配器构造函数 f.e

public class MyAdapterRecyclerView extends RecyclerView.Adapter<MyAdapterRecyclerView.MyViewHolder> {
......
    OnItemInteractListener mListner;
    public MyAdapterRecyclerView(ArrayList<Manga> dataSet, OnItemInteractListener listener){
    this.mListner = listener;
    ......
    // your adapter code
    public interface OnItemInteractListener{
        void onItemInteract(int position);
    }
}

在你的片段中

public class MangasSearchFragment extends Fragment implements MyAdapterRecyclerView.OnItemInteractListener{
// this will automatically ask you to override the onItemIteract method where you'll display your toast or open your fragment 
....
// your fragment code 
mAdapter = new MyAdapterRecyclerView(mangaTempList, this); // pass the listener to adapter using this

这基本上就是适配器和片段之间的通信方式每当用户单击某个项目时，您都会在适配器中使用该 mListener 变量监听用户点击的简单方法是在 onBindViewHolder 方法中使用

viewHolder.YourView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mListener.onItemInteract(position);
            }
        }

所以你的最终代码应该是这样的 MyAdapterRecyclerView

public class MyAdapterRecyclerView extends RecyclerView.Adapter<MyAdapterRecyclerView.MyViewHolder> {
private ArrayList<Manga> mDataSet;
private Context context;
OnMangaBookClickListener mListener;
public MyAdapterRecyclerView(ArrayList<Manga> dataSet, OnMangaBookClickListener listener) {
    mDataSet = dataSet;
    this.mListener = listener;
}

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

    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycleview_item, parent, false);
    //  final RecyclerView.ViewHolder holder = new MyViewHolder(view);
    this.context = parent.getContext();
    return new MyViewHolder(view);//, communicator);
}

@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, final int position) {
    Picasso.get().load(mDataSet.get(position).getPosterPicture()).into(holder.imageviewBookCover);
    holder.tvBookTitle.setText("This is book nr: " + position + " and title " + mDataSet.get(position).getTitle());
    holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mListener.onMangaBookClick(position);
        }
    });
}

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


private static OnMangaBookClickListener onMangaBookClickListener;

public static class MyViewHolder extends RecyclerView.ViewHolder  {
    public ImageView imageviewBookCover;
    public TextView tvBookTitle;
    
    public View itemView;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        this.itemView = itemView;
        imageviewBookCover = itemView.findViewById(R.id.imageView_bookcover);
        tvBookTitle = itemView.findViewById(R.id.textView_booktitle);

    }

}

public interface OnMangaBookClickListener {
    void onMangaBookClick(int position);
    }
}

和 MangasSearchFragment

public class MangasSearchFragment extends Fragment implements  MyAdapterRecyclerView.OnMangaBookClickListener{

private RecyclerView recyclerView;
private MyAdapterRecyclerView mAdapter;
private RecyclerView.LayoutManager layoutManager;
private Bundle results;
private ArrayList<Manga> mangaTempList;


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_mangas_to_search, container, false);
    Context context = getActivity();
    recyclerView = view.findViewById(R.id.recyclerview_manga_book);
    mangaTempList = new JsonHandling(context).getMangaBookJson();

    // use this setting to improve performance if you know that changes
    // in content do not change the layout size of the RecyclerView
    recyclerView.setHasFixedSize(true);

    // use a linear layout manager
    layoutManager = new LinearLayoutManager(context);
    recyclerView.setLayoutManager(new GridLayoutManager(context, 3));

    // specify an adapter (see also next example)
    mAdapter = new MyAdapterRecyclerView(mangaTempList, this);
    recyclerView.setAdapter(mAdapter);

    return view;
}

@Override
public void onMangaBookClick(int position) {
    Toast.makeText(getContext(), "item "+position, 

Toast.LENGTH_SHORT).show();
    }}

编辑 这是第二部分，在您使用 Toast 的地方使用该代码

在 FragmentA 中，在 onClickListenter 中使用它并传递位置（或使用 bundle 的任何数据）

public class MangasSearchFragment extends Fragment implements  MyAdapterRecyclerView.OnMangaBookClickListener{

private RecyclerView recyclerView;
private MyAdapterRecyclerView mAdapter;
private RecyclerView.LayoutManager layoutManager;
private Bundle results;
private ArrayList<Manga> mangaTempList;
int containerID = 0;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
   containerID = container.getId();
   ... // your code 
 }
@Override
public void onMangaBookClick(int position) {

   Bundle bundle = new Bundle();
   bundle.putInt("position", position);
   FragmentB fragmentB = new FragmentB();
   fragmentB.setArguments(bundle);
   getActivity().getSupportFragmentManager().beginTransaction()
             .replace(containerID, fragmentB, "FragmentB")
             .addToBackStack(null)
             .commit();
   }}

并在 FragmentB 中使用 getArguments() 来检索数据

int position =  getArguments().getInt("position");

将此添加到片段

(mainActifity)fragment --> 使用接口从列表传递对象的新片段

(mainActifity)fragment --> new fragment passing object from list using an interface

java

android

fragment