RecyclerView 的簡單使用

時間 2019-12-05

標籤 recyclerview 簡單使用简体版

原文原文鏈接

自從Android 5.0以後，googlet推出了一個RecyclerView控件，他是support-v7包中的新組件，是一個強大的滑動組件，與經典的ListView相比，一樣擁有item回收複用的功能，RecyclerView至關因而ListView的升級版。java

RecyclerView封裝了ViewHolder的回收複用，也就是說RecyclerView標準化了ViewHolder,編寫Adapter面向的是ViewHolder而不是View了，複用的邏輯被封裝了，寫起來更加簡單。android

RecyclerView提供一種插拔式的體驗，高度的解耦，異常的靈活，針對一個Item的顯示RecyclerView專門抽取了相應的類，來控制Item的顯示，使其的擴展性特別強。bash

引入RecyclerVIew

compile 'com.android.support:recyclerview-v7:25.1.0'

建立佈局文件

主佈局文件

/*activity_main.xml*/
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.manu.mrecyclerview.MainActivity">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </android.support.v7.widget.RecyclerView>
</LinearLayout>

Item佈局文件

/*item.xml*/
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp">
    <TextView
        android:id="@+id/tv_recycle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="data"
        android:background="#cac3c3"
        android:padding="10dp"
        android:textSize="20sp"/>
</LinearLayout>

建立Adapter

RecyclerView的Adapter要比ListView的Adapter設置起來稍微複雜一點，這也是RecyclerView高度解耦的體現，雖然代碼複雜一點，但擴展性很好，下面介紹一下實現RecyclerView的Adapter的三個方法：dom

onCreateViewHolder()

該方法主要是爲每一個Item加載一個View，可是該方法返回的是一個ViewHolder，該方法吧View直接封裝的ViewHolder中，而後咱們面向的是ViewHolder這個實例，這個ViewHolder也由本身編寫，但不用像ListView調用convertView.setTag(vh)和convertView.getTag()了。ide

onBindViewHolder()

該方法主要用來把數據綁定在View上，直接提供一個ViewHolder而不是convertView。佈局

getItemCount()

該方法返回選項總數。學習

Adapter代碼

/**
 * Created by jzman on 2017/5/13 0013.
 */
public class RvAdapter extends RecyclerView.Adapter<RvAdapter.DataViewHolder>{
    private Context mContext;
    private ArrayList<String> mList;

    public RvAdapter() {}

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

    //用於建立ViewHolder
    @Override
    public DataViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.item,null);
        //使用代碼設置寬高（xml佈局設置無效時）
        view.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT));
        DataViewHolder holder = new DataViewHolder(view);
        return holder;
    }
    //綁定數據
    @Override
    public void onBindViewHolder(DataViewHolder holder, int position) {
        holder.tv_data.setText(mList.get(position));
    }
    //數據總數
    @Override
    public int getItemCount() {
        return mList.size();
    }

    //建立ViewHolder
    public static class DataViewHolder extends RecyclerView.ViewHolder{
        TextView tv_data;
        public DataViewHolder(View itemView) {
            super(itemView);
            tv_data = (TextView) itemView.findViewById(R.id.tv_recycle);
        }
    }

使用StaggeredGridLayoutManager管理器時，Adapter參考以下：this

/**
 * Created by jzman on 2017/5/13 0013.
 * RecycleView的Adapter
 */
public class RvAdapter extends RecyclerView.Adapter<RvAdapter.DataViewHolder>{
    private Context mContext;
    private RecyclerView recyclerView;
    private ArrayList<String> mList;
    private ArrayList<Integer> mHeight;

    public RvAdapter() {}

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

    /**
     * 初始化每一個Item的高度（瀑布流效果）
     * @return
     */
    public ArrayList<Integer> initHeight(){
        mHeight = new ArrayList<>();
        for (int i=0;i<mList.size();i++){
            mHeight.add((int) (Math.random()*300)+200);
        }
        return mHeight;
    }

    /**
     * 用於建立ViewHolder
     * @param parent
     * @param viewType
     * @return
     */
    @Override
    public DataViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(mContext).inflate(R.layout.item,null);
        //使用代碼設置寬高（xml佈局設置無效時）
        view.setLayoutParams(new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT));
        DataViewHolder holder = new DataViewHolder(view);
        return holder;
    }

    /**
     * 綁定數據
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(DataViewHolder holder, int position) {
        //設置每一個Item的高度
        ViewGroup.LayoutParams h = holder.tv_data.getLayoutParams();
        h.height = mHeight.get(position);
        holder.tv_data.setText(mList.get(position));
    }

    /**
     * 選項總數
     * @return
     */
    @Override
    public int getItemCount() {
        return mList.size();
    }

    /**
     * 建立ViewHolder
     */
    public static class DataViewHolder extends RecyclerView.ViewHolder{
        TextView tv_data;
        public DataViewHolder(View itemView) {
            super(itemView);
            tv_data = (TextView) itemView.findViewById(R.id.tv_recycle);
        }
    }
    /**
     *   將RecycleView附加到Adapter上
     */
    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        this.recyclerView= recyclerView;
        //初始化每一個Item的高度
        initHeight();
    }
    /**
     *   將RecycleView從Adapter解除
     */
    @Override
    public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
        super.onDetachedFromRecyclerView(recyclerView);
        this.recyclerView = null;
    }
}

MainActivity

/**
 * Created by jzman on 2017/5/13 0013.
 */
public class MainActivity extends AppCompatActivity {
    private RecyclerView rv;
    RvAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        rv = (RecyclerView) findViewById(R.id.rv);
        //設置佈局管理器
        rv.setLayoutManager(new LinearLayoutManager(this));//線性
//        rv.setLayoutManager(new GridLayoutManager(this,4));//線性
//        rv.setLayoutManager(new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.VERTICAL));//線性
        adapter = new RvAdapter(this,initData());
        rv.setAdapter(adapter);
    }
    public static ArrayList<String> initData(){
        ArrayList<String> arrayList = new ArrayList<>();
        for (int i=0;i<50;i++){
            arrayList.add("第"+i+"條數據");
        }
        return arrayList;
    }
}