android 5.0新特性 RecyclerView使用初級

     RecyclerView是google 用來取代ListView和GridView等控件。其很好地抽象出了ViewHolder等類。本文給出一個RecyclerView的demo：

1.若是android studio 需要配置gradle

  配置如下：

dependencies {
      ...
    compile 'com.android.support:recyclerview-v7:22.2.1'
}
           
   

2. activity_main.xml（很簡單隻有一個RecyclerView）

<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:id="@+id/main_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical" />

</LinearLayout>
           

3. MainActivity.java檔案

public class MainActivity extends ActionBarActivity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;
    private List<String> mData;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
        // setlayoutManager
        mLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(mLayoutManager);
        //setAdapter
        mData = new ArrayList<>();
        for (int i = 0; i < 40; i++) {
            mData.add("this is position:" + i);
        }
        mAdapter = new MyRecycleViewAdapter(mData, this);
        mRecyclerView.setAdapter(mAdapter);
    }

}
           

        在該類中，我們設定了RecyclerView的Adapter。 另外注意，RecyclerView并沒有指定元素的顯示方式（如水準、gridView、瀑布流方式）。本文僅給出簡單的顯示方式，設定其RecyclerView的LayoutManager()為LinearLayoutManager。

4.item.main.xml布局為左邊textView 右邊一個image

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/item"
    android:layout_width="match_parent"
    android:layout_height="?listPreferredItemHeight"
    android:clickable="true"
    android:focusable="true"
    android:foreground="?selectableItemBackground">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <ImageView
        android:id="@+id/handle"
        android:layout_width="?listPreferredItemHeight"
        android:layout_height="match_parent"
        android:layout_gravity="center_vertical|right"
        android:scaleType="center"
        android:src="@drawable/ic_reorder_grey_500_24dp" />
</FrameLayout>
           

5.  現在我們來定義MyRecyclerViewAdapter如下（需要繼承一個攜帶<ViewHolder（泛型）>的RecyclerView.Adapter類）

public class MyRecycleViewAdapter extends RecyclerView.Adapter<MyRecycleViewAdapter.MyViewHolder> {
    private List<String>mData;
    private Context mContext;

    public MyRecycleViewAdapter(List<String> mData,Context context) {
        this.mData = mData;
        mContext=context;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView= LayoutInflater.from(mContext).inflate(R.layout.item_main,parent,false);
        return new MyViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.text.setText(mData.get(position));
        holder.itemView.setTag(mData.get(position));
    }

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

    public static class MyViewHolder extends RecyclerView.ViewHolder{
        public ImageView image;
        public TextView text;
        public MyViewHolder(View itemView) {
            super(itemView);
            image= (ImageView) itemView.findViewById(R.id.handle);
            text= (TextView) itemView.findViewById(R.id.text);
        }
    }
}
           

以上代碼，其實經常使用listView的同學一定不陌生。需要ViewHolder，以及将資料填充。

public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)       
    
方法需要我們傳回一個自己建立的ViewHolder      
    
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position)      
        
該方法需要我們将資料和ViewHolder綁定。