Java （主要活动）片段-->；使用接口从列表中传递对象的新片段

我在两件事上有困难

不知何故，我无法使我的界面

onClickListener

正常工作

第一个问题解决后，我不知道如何启动

fragmentB

来显示书籍（

fragmentA

有一个

RecycleView

）

我是否在stack/google上检查并尝试了解决方案

是的，在过去的两天里，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，因为我还是一个初学者

FragmentA（mangasearch）

是

main活动的一部分

（不确定是否要查看

main活动的代码

）

FragmentB

将是一个新的片段，按下后将被销毁并返回到

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);
    }
}

---

对于onClickListener，您可以在适配器中创建一个接口，让片段实现它，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);
    }
}

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 听用户点击的简单方法是在onBindViewHolder方法中 使用

所以你的最终代码应该是这样的 MyAdapterRecyclView

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);
    }
}

---

---

将此添加到片段

中，但onClick从未被调用，toast中的What消息从未显示……我以为你说过你解决了问题，正如你所写的那样（在我解决了第一个问题之后）：DD好的，我会更改我的答案，并标记为答案，如果它对你有帮助；）这意味着当我解决这个问题时，我会遇到问题2：我找到你了：DD你正在使用一种奇怪的方法来实现onClickListener如果我修复你的方法或给你演示更简单的方法，应该比idk容易得多：D请演示/教我简单的方法，因为我完全迷路了：D

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 

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

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);
    }
}

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();
    }}

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();
   }}

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