【Android】RecyclerView中点击Item弹出PopupWindow

---

前言

效果：

一、LayoutInflater.from()上下文问题

【核心问题在于PopupWindow上下文环境不知道怎么写？】

onClick()中的View popview = LayoutInflater.from(mcontext).inflate(R.layout.popupwindow_layout, null, false);
的from()参数
和onCreateViewHolder()中的View view= LayoutInflater.from(mcontext).inflate(R.layout.listview_item,parent,false);的上下文是同一个上下文。

可以写parent.getContext()，也可以写个mcontext类成员变量。

写法1：mcontext

ItemAdapter.java：RecyclerView的自定义Adapter

public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ViewHolder> {

    private List<Item> mitemList;
    private Context mcontext;

    static class ViewHolder extends RecyclerView.ViewHolder{...}

    public ItemAdapter(Context context,List<Item> itemList)
    {
        this.mitemList=itemList;
        this.mcontext=context;
    }

    @Override
    public int getItemCount() {...}

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view= LayoutInflater.from(mcontext).inflate(R.layout.listview_item,parent,false);
        final ViewHolder viewHolder=new ViewHolder(view);

        final View popview=LayoutInflater.from(mcontext).inflate(R.layout.popupwindow_layout,null,false);
        ....
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {...}
}

写法2:parent.getContext()

@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.listview_item,parent,false);
    final ViewHolder viewHolder=new ViewHolder(view);

    final View popview=LayoutInflater.from(parent.getContext()).inflate(R.layout.popupwindow_layout,null,false);
    final PopupWindow popupWindow=new PopupWindow(
            popview,
            ViewGroup.LayoutParams.WRAP_CONTENT,
            ViewGroup.LayoutParams.WRAP_CONTENT,
            true
    );

    viewHolder.itemBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            popupWindow.showAtLocation(popview,Gravity.CENTER,0,0);
        }
    });
    popview.findViewById(R.id.close).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            popupWindow.dismiss();
        }
    });
    return viewHolder;
}

二、设置文本问题

效果：
要设置弹出窗口中文本根据点击不同的条目会有不同显示。

【核心问题：找不到textView的R.id】
不知道为什么它能显示别的控件的R.id的选项，但不会显示我们想要的TextView的R.id.content。只有你自己打出来才行。

【核心问题：setText()方法没有】
分开写才行，合在一起写就没有。

问题：

解决：

TextView textView=popview.findViewById(R.id.content);
textView.setText("hello");

完整源码

> ItemAdapter.java

```java
package com.example.myapplication;

import android.content.Context;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.PopupWindow;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.List;

public class ItemAdapter extends RecyclerView.Adapter {

    private List mitemList;
    private Context mcontext;

    static class ViewHolder extends RecyclerView.ViewHolder
    {
        TextView itemName;
        TextView itemProgress;
        Button itemBtn;

        public ViewHolder(View view)
        {
            super(view);
            itemName=view.findViewById(R.id.name);
            itemProgress=view.findViewById(R.id.progress);
            itemBtn=view.findViewById(R.id.show);
        }
    }

    public ItemAdapter(Context context,List itemList)
    {
        this.mitemList=itemList;
        this.mcontext=context;
    }

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

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view= LayoutInflater.from(mcontext).inflate(R.layout.listview_item,parent,false);
        final ViewHolder viewHolder=new ViewHolder(view);

        final View popview=LayoutInflater.from(mcontext).inflate(R.layout.popupwindow_layout,null,false);
        final PopupWindow popupWindow=new PopupWindow(
                popview,
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT,
                true
        );

        viewHolder.itemBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int pos=viewHolder.getAdapterPosition();
                TextView textView=popview.findViewById(R.id.content);
                switch (pos)
                {
                    case 0:
                    {
                        textView.setText("hello");
                        break;
                    }
                    case 1:
                    {
                        textView.setText("world");
                        break;
                    }
                    default:
                        break;
                }
                popupWindow.showAtLocation(popview,Gravity.CENTER,0,0);
            }
        });
        popview.findViewById(R.id.close).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                popupWindow.dismiss();
            }
        });
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Item item=mitemList.get(position);
        holder.itemName.setText(item.getName());
        holder.itemProgress.setText(item.getProgress());
    }
}