RecyclerView 基础使用

使用方法
1、添加引用
implementation 'com.android.support:recyclerview-v7:27.1.1'
2、创建布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   tools:context=".recycler.RecyclerActivity">

   <android.support.v7.widget.RecyclerView
       android:id="@+id/recyclerview"
       android:layout_width="match_parent"
       android:layout_height="wrap_content" />
</LinearLayout>

3 、创建item

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp"
    android:gravity="center"
    android:orientation="horizontal">

    <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:src="@drawable/ic_launcher_background" />

    <TextView
        android:layout_marginLeft="20dp"
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@color/colorAccent"
        android:textSize="22sp" />
</LinearLayout>

4、创建Adapter
RecyclerView的apater 和listview、Gradview 的adapter有些不同 ，Holider 需要继承RecyclerView.ViewHolder，adapter 需要继承RecyclerView.Adapter<T>。
主要方法：
创建ViewHolder

    @NonNull
    @Override
    public MyHolider onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
      //ViewHolider 和布局文件的绑定
        View view = LayoutInflater.from(mContext).inflate(R.layout.item_name, null);
        MyHolider myHolider = new MyHolider(view);
        return myHolider;
    }

设置item显示的内容

 @Override
    public void onBindViewHolder(@NonNull MyHolider holder, int position) {
        holder.name.setText(mList.get(position));
    }

item 的数量

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

ViewHolider

 public class MyHolider extends RecyclerView.ViewHolder {
  //此处可以添加自己显示的属性
        private TextView name;

        public MyHolider(View itemView) {
            super(itemView);
//..........
            name = itemView.findViewById(R.id.name);
        }
    }

adapter 全部代码

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyHolider> {

    private List<String> mList;
    private Context mContext;

    public MyAdapter(List<String> mList, Context mContext) {
        this.mList = mList;
        this.mContext = mContext;
    }

    @NonNull
    @Override
    public MyHolider onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.item_name, null);
        MyHolider myHolider = new MyHolider(view);
        return myHolider;
    }

    @Override
    public void onBindViewHolder(@NonNull MyHolider holder, int position) {
        holder.name.setText(mList.get(position));
    }

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


    public class MyHolider extends RecyclerView.ViewHolder {

        private TextView name;

        public MyHolider(View itemView) {
            super(itemView);
            name = itemView.findViewById(R.id.name);
        }
    }

}

Activity 代码

public class RecyclerActivity extends AppCompatActivity {

    RecyclerView mRecyclerView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recycler);
        mRecyclerView = findViewById(R.id.recyclerview);
//        mRecyclerView.setLayoutManager(new GridLayoutManager(this,5));
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(new MyAdapter(getData(),this));
    }


    private List<String> getData() {
        List<String> list = new ArrayList<>();
        for (int i = 1; i < 30; i++) {
            list.add(" 张三  " + i + "  号");
        }
        return list;
    }
}

正常listView效果
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
效果

image.png

GridView 效果

后面的数字是一行显示几个
 mRecyclerView.setLayoutManager(new GridLayoutManager(this,2));

效果

image.png