RecycleView控件

短命女 2021-09-28 07:40 390阅读 0赞

**目录**

*  RecycleView的基本用法
 *  实现横向滚动和瀑布流布局
 *  RecycleView的点击事件

ListView不使用一些技巧提升它的运行效率，性能就会很差，而且也不能实现横屏滚动。

官方推荐使用RecycleView

**一：RecycleView的基本用法**

要使用这个控件，要在项目的build.gradle中添加相应的依赖库，因为它和百分比布局一样是新增加的

compile 'com.android.support:appcompat-v7:24.2.1'
        //百分比布局
        compile 'com.android.support:percent:24.2.1'
        //RecycleView控件(这个)
        compile 'com.android.support:recyclerview-v7:24.2.1'
        //声明测试用例库的
        testCompile 'junit:junit:4.12'

![20190315215311878.png][]

package com.example.testone;
    
    public class Friend {
        private String friend;
        private int imageId;
    
    
        public Friend(String friend, int imageId) {
            this.friend = friend;
            this.imageId = imageId;
        }
    
    
        public int getImageId() {
            return imageId;
        }
    
        public void setImageId(int imageId) {
            this.imageId = imageId;
        }
    
        public String getFriend() {
            return friend;
        }
    
        public void setFriend(String friend) {
            this.friend = friend;
        }
    }

![2019031521540988.png][]

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">
    
    
        <ImageView
            android:layout_width="50sp"
            android:layout_height="50sp"
            android:id="@+id/friend_image"/>
    
    
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/friend_name"
            android:layout_gravity="center_vertical"
            android:layout_marginLeft="10dp"/>
    
    
    </LinearLayout>

![20190315232525668.png][]

package com.example.testone;
    
    
    import android.support.v7.widget.RecyclerView;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    import java.util.List;
    
    
    //这个适配器继承自RecyclerView.Adapter，并将泛型指定为FriendAdapter.ViewHolder
    public class FriendAdapter extends RecyclerView.Adapter<FriendAdapter.ViewHolder> {
        private List<Friend> mFriendList;
    
    
        //内部类，继承RecyclerView.ViewHolder
        static class ViewHolder extends RecyclerView.ViewHolder{
            ImageView friendImage;
            TextView friendName;
    
            //ViewHolder的构造函数要传入一个View参数,这个参数通常就是RecyclerView子项的最外层布局,这样就可以用findViewById方法获得布局中的实例
            public ViewHolder(View view){
                super(view);
                friendImage = (ImageView) view.findViewById(R.id.friend_image);
                friendName = (TextView) view.findViewById(R.id.friend_name);
            }
        }
    
    
        //FriendAdapter也有一个构造函数，这个方法用于把要展示的数据源传进来，并赋值给全局变量mFriendList
        public FriendAdapter(List<Friend> friendList){
            mFriendList = friendList;
        }
    
    
        //由于FriendAdapter是继承RecyclerView.Adapter的，那么就要重写下面三个方法
        @Override
        //用于创建ViewHolder实例的
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            //将friend_item布局加载进来
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.friend_item,parent,false);
            //创建一个ViewHolder实例，把加载出来的布局传入到构造函数中
            ViewHolder holder = new ViewHolder(view);
            //最后将ViewHolder的实例返回
            return holder;
        }
    
    
        @Override
        //用于对RecyclerView子项的数据进行赋值，会在每个子项被滚动到屏幕内的时候执行
        public void onBindViewHolder(ViewHolder holder, int position) {
            //通过position参数得到当前项的Friend的实例
            Friend friend = mFriendList.get(position);
            //将数据设置到ViewHodle的ImageView和TextView中
            holder.friendImage.setImageResource(friend.getImageId());
            holder.friendName.setText(friend.getFriend());
        }
    
        @Override
        //告诉RecyclerView一共有多少子项
        public int getItemCount() {
            return mFriendList.size();
        }
    }

![20190315232609384.png][]

package com.example.testone;
    
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.support.v7.widget.LinearLayoutManager;
    import android.support.v7.widget.RecyclerView;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.ArrayAdapter;
    
    import android.widget.ListView;
    import android.widget.Toast;
    
    import java.util.ArrayList;
    import java.util.List;
    
    
    public class MainActivity extends AppCompatActivity{
    
        private List<Friend> friendList = new ArrayList<>();
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            //初始化水果数据
            initFriend();
            //获得RecyclerView实例
            RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
            //创建一个LinearLayoutManager对象
            //LayoutManager用于指定RecyclerView布局方式，这里使用LinearLayoutManager是线性布局的意思
            LinearLayoutManager layoutManager = new LinearLayoutManager(this);
            //将LinearLayoutManager对象设置到RecyclerView中
            recyclerView.setLayoutManager(layoutManager);
            //创建FriendAdapter实例，并将Friend数据传入到FriendAdapter的构造函数中
            FriendAdapter adapter = new FriendAdapter(friendList);
            //完成适配器的配置
            recyclerView.setAdapter(adapter);
        }
    
            private void initFriend(){
            //数据少，要不不足以占满整个屏幕，循环两遍
            for (int i = 0;i<10;i++){
                //在Friend类的构造函数中将名字和投票传入
                Friend hyy = new Friend("hyy",R.drawable.katon);
                //把创建好的对象添加到friendList中
                friendList.add(hyy);
                Friend hyr = new Friend("hyr",R.drawable.renwu);
                friendList.add(hyr);
                Friend hyj = new Friend("hyj",R.drawable.katon);
                friendList.add(hyj);
                Friend hyk = new Friend("hyk",R.drawable.renwu);
                friendList.add(hyk);
                Friend hyo = new Friend("hyo",R.drawable.katon);
                friendList.add(hyo);
                Friend hyp = new Friend("hyp",R.drawable.renwu);
                friendList.add(hyp);
            }
        }
    
    
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjcxNzkyOA_size_16_color_FFFFFF_t_70][]

二：实现横向滚动和瀑布流布局

三：RecycleView的点击事件

[20190315215311878.png]: /images/20210923/3276611ad5224053ac62f46cf7854795.png
[2019031521540988.png]: /images/20210923/43428236a8ea41cd8a7f4803d269640a.png
[20190315232525668.png]: /images/20210923/8c4f2030a610467f945bd6014df0ecb6.png
[20190315232609384.png]: /images/20210923/ae70d4771618491cbf595ed513f5656f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjcxNzkyOA_size_16_color_FFFFFF_t_70]: /images/20210923/2d9b49ccaa2f407b8b4dc03ef39c13a4.png