十七、RecyclerView

一、导入依赖包

dependencies {
    //添加 RecyclerView的依赖包
    implementation 'androidx.recyclerview:recyclerview:1.2.1'
}

二、代码示例

1.布局页面

<?xml version="1.0" encoding="utf-8"?>


    

<?xml version="1.0" encoding="utf-8"?>


    

2.后台代码

2.1 创建Bean类

package com.example.myrecyclerview;

public class Bean {

    private  String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

　　2.2  创建MyAdapter，继承 RecyclerView.Adapter ，需要手动创建实现 item 的点击监听事件

package com.example.myrecyclerview;

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

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

import java.util.List;

public class MyAdapter extends RecyclerView.Adapter {

    private List data;
    private Context context;

    public  MyAdapter(List data1,Context context1) {
        this.data=data1;
        this.context=context1;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //获取布局
        View view = View.inflate(context,R.layout.recycleview_list,null);
        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.tv.setText(data.get(position).getName());
    }

    /**
     * 显示多少个
     * */
    @Override
    public int getItemCount() {
        return data==null?0:data.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        private TextView tv;
        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            tv=itemView.findViewById(R.id.txt);

            //实现监听方法的回调
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if (mOnItemClickListener!=null)
                    {
                        mOnItemClickListener.onRecyclerItemClick(getAdapterPosition());
                    }
                }
            });
        }
    }


    //创建接口
    public interface  OnRecyclerItemClickListener{
        void onRecyclerItemClick(int position);
    }

    private OnRecyclerItemClickListener mOnItemClickListener;

    //创建设置监听的方法
    public void  setRecyclerItemClickListener(OnRecyclerItemClickListener listener){
        mOnItemClickListener = listener;
    }
}

　　2.3 主程序调用，布局设置（注：瀑布流的显示效果会填充 没有使用的区域），最后实现 setRecyclerItemClickListener 的监听信息，进行item点击的回调显示。

package com.example.myrecyclerview;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.StaggeredGridLayoutManager;

import android.os.Bundle;
import android.util.Log;
import android.widget.LinearLayout;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List data=new ArrayList<>();

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

        for (int i=0;i<1000;i++){
            Bean bean=new Bean();
            bean.setName("享学"+i);
            data.add(bean);
        }

        //实现 RecyclerView
        RecyclerView recyclerView = findViewById(R.id.rv);
        //设置布局
        //垂直
        /*LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(linearLayoutManager);*/
        //网格  整齐网格布局
        /*GridLayoutManager gridLayoutManager = new GridLayoutManager(this,3);
        recyclerView.setLayoutManager(gridLayoutManager);*/
        //瀑布流  自动填充剩余空间
        StaggeredGridLayoutManager staggeredGridLayoutManager =
                new StaggeredGridLayoutManager(3,
                        LinearLayout.VERTICAL);
        recyclerView.setLayoutManager(staggeredGridLayoutManager);

        MyAdapter myAdapter = new MyAdapter(data,this);
        recyclerView.setAdapter(myAdapter);

        myAdapter.setRecyclerItemClickListener(new MyAdapter.OnRecyclerItemClickListener() {
            @Override
            public void onRecyclerItemClick(int position) {
                Log.e("tag", "onRecyclerItemClick: "+position );
            }
        });
    }
}